FB/EK Holden Stromberg Carburettion Enthusiasts Guide Addendum 1

FB/EK HOLDEN

STROMBERG CARBURETTION

ENTHUSIASTS GUIDE

ADDENDUM 1

REVISION DATE UPDATE

0 October 2011 Initial draft for review.

Addendum 1 September 2014 First addendum for update of original

document

Table of Contents

1 Background ........................................................................................................................................... 3 2 Not all Strombergs Are Equal… the Zenith Connection ........................................................................ 4 3.2 Australian Stromberg Carburettor Codes .............................................................................................. 5 3.3 Main Metering Jets .............................................................................................................................. 12 4.8 Choke System ..................................................................................................................................... 13 15 Methanol and Ethanol ............................................................................................................................ 14

15.1 The Float System ........................................................................................................................... 14 15.2 The Idle System ............................................................................................................................. 16 15.3 The Main Metering System ............................................................................................................ 19 15.4 The Accelerating System ............................................................................................................... 20 15.5 The Power System ......................................................................................................................... 21 15.6 The Choke System ........................................................................................................................ 23 15.7 Fuel Pump and Tank ...................................................................................................................... 23

1 Background

This document aims to provide an update to the FB/EK Holden Stromberg Carburettion Enthusiasts

Guide Revision 0. It contains:

updated information to the original document, where corrections have been made by various contributors or through detection of my own errors, and

additional information that has come to light since the document was written.

Section numbers used in this Addendum refer to the original numbers used in the FB/EK Holden

Stromberg Carburettion Enthusiasts Guide Revision 0.

Anecdotally, the original document was posted (via various early Holden internet forums) at the Scribd

online document sharing site. Since publishing, the document has received over 10,400 views.

Like all things automotive, installing, operating and maintaining a carburettor comes with a risk.

Leaking fuel lines can lead to fires, and items dropped down a carburettor throat can cause massive

engine damage (amongst other hazards). Any advice contained in this document is to be taken at the

reader’s risk – qualified mechanics should be consulted where appropriate.

2 Not all Strombergs Are Equal… the Zenith Connection

The text shown in Section 2 originally read:

"Zenith Strombergs were fitted to LC Holden 161S GTR-XU1 161S engines (triple 1.5” 150 CDS side

draught), LJ Holden 202 XU1 engines (triple 175 CD2-S side draught) and HB Holden

BrabhamToranas (single 150 CD sidedraught).”

This is not correct. The text should read:

"Zenith Strombergs were fitted to LC Holden 186ci GTR-XU1 engines (triple 1.5” 150 CDS side

draught), LJ Holden 202 XU1 engines (triple 175 CD2-S side draught were fitted to both road and

Bathurst variants) and HB Holden Series 70 (single 1.5” 150 CD side draught) and Brabham Toranas

(twin 1.5” 150 CD side draught).

3.2 Australian Stromberg Carburettor Codes

The table shown in Section 3.2 has been updated as below. This brings the table to a complete listing of Australian Stromberg carburetors up to 1979. Items

shown in black text are additional to the original table, whilst items shown in red text appeared in the original table but have been amended. Note that the

correct, unchanged data in the original table is not presented below.

Code Model Specification Vehicle

1-9C2CA BXOV-2 A19102 Universal carburettor, 211

/16” flange bolt centres.

1-98C BXUV-3 A19103 Universal carburettor, 215


1-3401 BXUV-3 2375006 Universal carburettor, 215


1-3400 BXUV-3 2375011 Universal carburettor, 215


2-3102 BV-2 2375023 Ford Falcon XR (1966-1967) and Fairlane ZA (1967-1968) 200ci six cylinder engines.

2-3109 BV-2 2375034 Ford Falcon XT and Fairlane ZB 222ci six cylinder engines with automatic transmissions (1968).

2-3112 BV-2 2375038 Ford Falcon XT and Fairlane ZB 221ci six cylinder engines with manual transmissions (1968).

2-3114 BV-2 2375041 Ford Falcon XT 188ci six cylinder engines (1968-1969).

2-3115 BV-2 2375042 Ford Falcon XT and Fairlane ZB 222ci six cylinder engines (1968-1969).

2-3116 BOV-2 2375046 Ford Falcon XW and Fairlane ZC 221ci six cylinder engines with manual and automatic transmissions (1969-

1970).

2-3118 BOV-2 2375048 Ford Falcon XY (1970) and Fairlane ZD (1970-1972) 250ci six cylinder engines with manual transmissions.

2-3123 WW 2375054 Ford Falcon XW and Fairlane ZC 302ci V8 engines with manual transmissions (1970).

2-3126 BOV-2 2375075 Ford Falcon XY (1970) and Fairlane ZD (1970-1972) 250ci six cylinder engines with automatic transmissions.

2-3133 WW 2375082 Ford Falcon XY (1971-1972) and Fairlane ZD (1970-1972) 302ci V8 engines (1971-1972).

2-3135 WW 2375089 Ford Falcon XA and Fairlane ZF 250ci 2V six cylinder engines (1972-1973).

2-3136 WW 2375090 Ford Falcon XA and Fairlane ZF 302ci V8 engines (1972-1973).

2-3137 BV-2 2375091 Ford Falcon XA, Cortina TC and Transit van 200ci six cylinder engines with manual transmissions (1972-1973).

2-3138 BV-2 2375092 Ford Falcon XA, Cortina TC and Transit van 200ci six cylinder engines with automatic transmissions (1972-1973).

2-3139 BOV-2 2375093 Ford Falcon XA and Fairlane ZF 250ci six cylinder engines with manual transmissions (1972).

2-3140 BOV-2 2375094 Ford Falcon XA , Fairlane ZF and Cortina TC 250ci six cylinder engines with automatic transmissions (1972-

1973).

2-3143 BOV-2 2375098 Ford Falcon XA, Fairlane ZF and Cortina TC 250ci six cylinder engines with manual transmissions (1972-1973).

2-3144 BOV-2 2375098 Ford Falcon XA, Fairlane ZF and Cortina TC 250ci six cylinder engines with manual transmissions (1972-1973).

2-3145 BOV-2 2375119 Ford Falcon XB (1973-1974) and Cortina TC-TD (1974) 200ci six cylinder engines with automatic transmissions

(1974).

2-3146 BOV-2 2375120 Ford Falcon XB (1973-1974) and Cortina TC-TD (1974) 200ci six cylinder engines with manual transmissions.

2-3147 BOV-2 2375121 Ford Falcon XB, Cortina TC-D and Fairlane ZF 250ci six cylinder engines with automatic transmissions (1973-

1974).

2-3148 BOV-2 2375122 Ford Falcon XB and Cortina TC-TD 250ci six cylinder engines with manual transmissions (1973-1974).

2-3151 BV-2 2375134 Ford Falcon XA and Cortina TC (1973) and Transit van (1973-1975) 200ci six cylinder engines with manual

transmissions (1973).

2-3152 BV-2 2375135 Ford Falcon XA and Cortina TC (1973) and Transit van (1973-1975) 200ci six cylinder engines with automatic

transmissions (1973).

2-3153 BOV-2 2375136 Ford Falcon XA, Fairlane ZF and Cortina TC 250ci six cylinder engines with manual transmissions (1973).

2-3154 BOV-2 2375137 Ford Cortina TC, Falcon XA and Fairlane ZF 250ci six cylinder engines with automatic transmissions (1973).

2-3155 WW 2375138 Ford Falcon XA and Fairlane ZF 250ci 2V six cylinder engines (1973).

2-3156 WW 2375139 Ford Falcon XA and Fairlane ZF 302ci V8 engines with manual and automatic transmissions (1973).

2-3161 BOV-2 2375156 Ford Falcon XB and Cortina TD (1975-1976) and Transit van (1976-1978) 200ci six cylinder engines with

automatic transmissions (1975-1976)

2-3162 BOV-2 2375157 Ford Falcon XB and Cortina TD (1975-1976) and Transit van (1976-1978) 200ci six cylinder engines with manual

transmissions (1975-1976).

2-3163 BOV-2 2375158 Ford Falcon XB and Cortina TC-D 250ci six cylinder engines with automatic transmissions (1975-1976).

2-3164 BOV-2 2375159 Ford Falcon XB and Cortina TD 250ci six cylinder engines with manual transmissions (1975-1976)

2-3169 BX 2375174 Ford XC 3.3L six cylinder engines with automatic transmissions (1976).

2-3170 BX 2375175 Ford XC 3.3L six cylinder engines with manual transmissions (1976).



2-3173 BX 2375178 Ford Cortina TD 3.3L six cylinder engines with automatic transmissions (1976)

2-3174 BX 2375179 Ford Cortina TD 3.3L six cylinder engines with manual transmissions (1976)

2-3175 BX 2375180 Ford Cortina TD 4.1L six cylinder engines with automatic transmissions (1976)

2-3176 BX 2375181 Ford Cortina TD 4.1L six cylinder engines with manual transmissions (1976)

2-3178 BX 2375188 Ford Cortina TD-TE 3.3L six cylinder engines with automatic transmissions (1977-1978)

2-3179 BX 2375189 Ford Cortina TD-TE 3.3L six cylinder engines with manual transmissions (1977-1978)

2-3180 BX 2375190 Ford Cortina TD-TE 4.1L six cylinder engines with automatic transmissions (1977)

2-3181 BX 2375191 Ford Cortina TD-TE 4.1L six cylinder engines with manual transmissions (1977)

2-3182 WW 2375186 Ford F100 truck 4.9L V8 engines (1976-1978).

2-3183 BX 2375192 Ford XC 3.3L six cylinder engines with automatic transmissions (1977-1978).

2-3184 BX 2375193 Ford XC 3.3L six cylinder engines with manual transmissions (1977-1978).



2-3187 BX 2375203 Ford Transit van 4.1L six cylinder engines (1978-1979).

2-3188 BX 2375207 Ford Cortina TE 4.1L six cylinder engines with automatic transmissions (1978).

2-3189 BX 2375208 Ford Cortina TE 4.1L six cylinder engines with manual transmissions (1978).







2-3197 BX 2375222 Ford XD 3.3L six cylinder engines with automatic transmissions (1979).

2-3198 BX 2375223 Ford XD 3.3L six cylinder engines with manual transmissions (1979).

2-3199 BX 2375226 Ford XD;TF 250ci six cylinder engines with automatic transmissions (1979).

2-3200 BX 2375227 Ford XD 4.1L six cylinder engines with manual transmissions (1979).

4-3504 BXUV-3 2375045 Chrysler Valiant VC, VE six cylinder 145hp (low compression) engines (1968-1970).

23-201 WW 381205 Holden HR, HK and HT 186ci six cylinder “S” engines with manual transmissions (1967-1969).

23-3021 BXUV-2 2375018 Holden HR, HK, HT and HG 186ci six cylinder economy (taxi) engines (April 1966 – 1971).

23-3022 BXUV-2 2375017 Holden HR, HK, HT and HG 161ci six cylinder economy (taxi) engines (April 1966 – 1971).

23-3045 WW 2375062 Holden HQ 253ci V8 engines with automatic transmissions (July 1971 to October 1972).

23-3046 WW 2375063 Holden HQ 253ci V8 engines with manual transmissions (earlier carburetor, 1971-1972).

23-3048 WW 2375065 Holden LC GTR Torana 173ci six cylinder “S” engines (1971-1972).

23-3049 BXUV-3 2375066 Bedford 300ci six cylinder petrol engines (1971).

23-3050 BXV-2 2375067 Holden HQ, LC and LJ Torana 173ci six cylinder engines with manual transmissions and commercial chassis cabs

with 173ci six cylinder engines (1971-1973)

23-3051 BXV-2 2375068 Holden HQ and LC and LJ Torana 173ci six cylinder engines with automatic transmissions (1971-1973).

23-3052 BXV-2 2375069 Holden LJ GTR Torana 3300cc six cylinder “S” engines (1972-1973) and Holden HQ 202ci six cylinder engines

with manual transmissions (1971-1973).

23-3053 BXV-2 2375070 Holden HQ and LJ 202ci six cylinder engines with automatic transmissions (1971-1973).

23-3054 BXUV-2 2375071 Holden LC and LJ Torana 138ci six cylinder engines with manual transmissions (1971-1973).

23-3057 BXUV-2 2375079 Holden LC and LJ 138ci six cylinder engines with automatic transmissions (1971-1973).

23-3062 BXUV-3 2375080 Bedford 300ci six cylinder petrol engines (1971-1976).

23-3063 WW 2375101 Holden HQ 253ci V8 engines with automatic transmissions (November 1972 to July 1973).

23-3064 WW 2375102 Holden HQ 253ci V8 engines with manual transmissions (later carburettor, November 1972-1973).

23-3073 BXUV-3 2375111 Holden HQ 173ci six cylinder engines with automatic transmissions (1973-1974).

23-3074 BXUV-3 2375112 Holden HQ 173ci six cylinder engines with manual transmissions and commercial chassis cabs 173ci six cylinder

engines (1973-1974)

23-3075 BXUV-3 2375113 Holden HQ 202ci six cylinder engines with automatic transmissions (1973-1974).

23-3076 BXUV-3 2375114 Holden HQ 202ci six cylinder engines with manual transmissions (1973-1974).

23-3077 WW 2375115 Holden HQ 253ci V8 engines with automatic transmissions (August 1973 to September 1974).

23-3078 WW 2375116 Holden HQ 253ci V8 engines with manual transmissions (August 1973 to September 1974).

23-3079 BXV-2 2375140 Bedford CF van 173ci six cylinder engines with manual transmissions (1973-1977).

23-3080 BXV-2 2375141 Bedford CF van 173ci six cylinder engines with automatic transmissions (1973-1977).

23-3081 BXUV-3 2375128 Holden LJ and LH Toranas 2850cc six cylinder engines with automatic transmissions (1973-1975).

23-3082 BXUV-3 2375127 Holden LJ and LH Toranas (1973-1975) 173ci six cylinder engines with manual transmissions and commercial

chassis cabs (1974-1975) with 173ci six cylinder engines.

23-3083 BXUV-3 2375130 Holden HJ (1974-1975) and LJ and LH Torana (1973-1975) 202ci six cylinder engines with automatic

transmissions.

23-3084 BXUV-3 2375129 Holden HJ (1974-1975) and LJ and LH Torana (1973-1975) 202ci six cylinder engines with manual transmissions.

23-3085 WW 2375132 Holden HJ and LH Torana 253ci V8 engines with automatic transmissions (1974-1975).

23-3086 WW 2375131 Holden HJ and LH Torana 253ci V8 engines with manual transmissions (1974-1975).

23-3089 BXUV-3 2375150 Holden 1975 LH and LX Toranas (1975-1976) 173ci six cylinder engines with manual transmissions and

commercial chassis cabs (1975-1976) with 173ci six cylinder engines.

23-3090 BXUV-3 2375151 Holden LH and LX Torana 173ci six cylinder engines with automatic transmissions (1975-1976).

23-3091 BXUV-3 2375152 Holden HJ and LH and LX Torana 202ci six cylinder engines with manual transmissions (1975-1976).

23-3092 BXUV-3 2375153 Holden HJ and LH and LX Torana 202ci six cylinder engines with manual transmissions (1975-1976).

23-3093 WW 2375154 Holden HJ and LH and LX Torana 4.2L V8 engines with manual transmissions (January 1975 to June 1977).

23-3094 WW 2375155 Holden HJ and LH and LX Torana 4.2L V8 engines with automatic transmissions (January 1975 to June 1977).

23-3098 WW 2375168 Holden HX and LX Torana 4.2L V8 engines with automatic transmissions (July 1976 to April 1977).

23-3099 WW 2375169 Holden HX and LX Torana 253ci V8 engines with manual transmissions (1976-1977).

23-3100 BX 2375170 Holden LX and UC Torana 173ci six cylinder engines with automatic transmissions (1976-1979)..

23-3101 BX 2375171 Holden LX and UC Torana 173ci six cylinder engines with manual transmissions (1976-1979).

23-3102 BX 2375172 Holden HX and LX Torana 202ci six cylinder engines with automatic transmissions (1976-1977).

23-3103 BX 2375173 Holden HX and LX Torana 202ci six cylinder engines with manual transmissions (1976).

23-3104 BXV-2 2375182 Bedford CF van 173ci six cylinder engines (1976-1978).

23-3105 BX 2375183 Holden HX and HZ 202ci six cylinder engines with automatic transmissions (utility and panelvan) and commercial

chassis cabs (1976-1979) 202ci six cylinder engines with automatic transmissions.

23-3106 BX 2375184 Holden HX and HZ 202ci six cylinder engines with manual transmissions (exchange utility) and commercial

chassis cabs (1976-1979) 202ci six cylinder engines with manual transmissions.

23-3107 BX 2375201 Holden HX and HZ and LX Torana 202ci six cylinder engines with manual transmissions (1977).

23-3108 BXUV-3 2375196 Bedford 300ci six cylinder petrol engines (1977-1979).

23-3109 BX 2375197

Holden HX and HZ (with manual transmissions) and LX and UC Torana (with automatic transmissions) 202ci six

cylinder (low compression) engines (1977-1979). Note that it is unusual for the same carburetor to be used on

manual and automatic vehicles. This may be a typographic error in the Stromberg manual. See 23-3110 for a

similar issue.

23-3110 BX 2375198

Holden HX and HZ (with automatic transmissions) and LX and UC Torana (with manual transmissions) 202ci six

cylinder (low compression) engines (1977-1979). Note that it is unusual for the same carburetor to be used on

manual and automatic vehicles. This may be a typographic error in the Stromberg manual. See 23-3109 for a

similar issue.

23-3111 WW 2375199 Holden HX and HZ, LX Torana and VB Commodore 4.2L V8 engines with automatic transmissions (May 1977 to

March 1980).

23-3112 WW 2375200 Holden HX and HZ, LX Torana and VB Commodore 4.2 V8 engines with manual transmissions (May 1977 to

March 1980).

23-3114 BX 2375204 Holden HZ and LX and UC Toranas, 202ci six cylinder engines with automatic transmissions (1977-1979).

23-3115 BX 2375205 Holden HX and HZ and LX and UC Toranas, 202ci six cylinder engines with manual transmissions (1978-1979).

23-3116 BX 2375206 Bedford CF van 3300cc six cylinder engines with manual transmissions (1978-1979).

23-3117 BX 2375211 Holden VB Commodore 2850cc six cylinder engines with automatic transmissions (1978-1979).

23-3118 BX 2375212 Holden VB Commodore 2850cc six cylinder engines with manual transmissions (1978-1979).

23-3119 BX 2375213 Holden VB Commodore 3300cc six cylinder engines with automatic transmissions (1978-1979).

23-3120 BX 2375214 Holden VB Commodore 3300cc six cylinder engines with manual transmissions (1978-1979).

23-3121 BX 2375215 Holden VB Commodore 3300cc six cylinder low compression engines with manual transmissions (1978-1979).

32-3300 BXUV-3 2375001 International Harvester AB160, AB162, AB164, AB182, ABT182, ACCO172, ACCO182, ACCO183 and

ACCOT182 (1962 – mid 1965), ABM160, ABM162 and ABM164 engines (late 1963 – mid 1965)

32-3301 BXUV-3 2375015 International Harvester AB160, AB162, AB164, AB182, ABT182, ABM160, ABM162 and ABM164, C1640-C1820,

AACO and ACCO series, D1710 (mid-1965 – 1968).

32-3302 BXUV-3 2375019 International Harvester C1100, C1200, C1300, C1500, C1510, CC1600, D1110, D1210, D1310, D1510, D1610,

AC1100, AC1200, AC1300, AC1500, AC1510, AC1600 and AC4X4 (late 1966 – 1968).

32-3303 BXUV-3 2375026 International Harvester special vehicle for Australian Army (twin carburetors, 1966-1975).

A-1 WW 2375074 Leyland P76 4.4L V8 engines with manual transmissions (1973-1974).

A-2 WW 2375133 Leyland P76 4.4L V8 engines with automatic transmissions (1973-1974).

A-3 WW 2375148 Leyland P76 4.4L V8 engines with manual transmissions (1974).

A-5 WW 2375148 Leyland P76 4.4L V8 engines with manual transmissions (1974).

A-4 WW 2375149 Leyland P76 4.4L V8 engines with automatic transmissions (1974).

A-6 WW 2375149 Leyland P76 4.4L V8 engines with automatic transmissions (1974).

3.3 Main Metering Jets

The information below is supplementary to the original Guide.

The original Guide contained some advice for those who wished to use adjustable main metering jets.

Whilst still not a big fan of them in twin and triple carb service, I have done some more thinking about

them. For adjustable main metering jets, the text shown in Section 3.3 originally read as follows:

“As an initial tuning point, the following may be used:

bring the engine up to operating temperature,

hold the engine speed at around 3000-3500rpm (mid throttle).

Slacken the lock nut on the adjustable jet then screw the adjuster in slowly until the engine speed starts to alter and run a little bit rough. Wind back the adjuster until the engine speed pick up and the engine no longer runs rough.

Tighten the lock nut.” Whilst this is valid information, I wish to present below a comparison between the adjustable main

metering jets and the factory fixed jets. This information may be useful as a more accurate starting

point when installing adjustable main metering jets. The table below has been put together by wet

testing a variety of fixed jets, and also two typical adjustable main metering jets:

Opening Equivalent Main Metering Jet (”)

Two turns 0.043

Three turns 0.061

Four Turns 0.067

Wide, wide open 0.073

This would suggest that as a starting point for most grey motors that 2½ turns open is a good guess,

whilst for twins and triples a shade over two turns open is a good starting point.

4.8 Choke System

The original text describes the poppet valve as follows:

“The choke valve is also fitted with a spring-loaded poppet valve. When the engine starts, if the choke

plate is jammed shut (choke lever pulled all the way out), the increased vacuum opens the poppet

valve, relieving some of the suction on the idle system and preventing flooding. A light buzzing noise

from the poppet valve washer can be heard if the engine is being overchoked in this fashion.”

The following text and diagram should be read in

conjunction with the above:

Additionally, the poppet valve serves another purpose. If

the throttle valve is slammed shut (say in between high-

speed gear changes), the inlet manifold vacuum can

increase greatly. If the vacuum is greater than about

22"Hg, the mixture can become too weak to ignite easily,

causing misfire. This can result in passing un-burnt into the

exhaust system where it can detonate (backfiring). The

poppet valve will alleviate this situation, and the

consequent emission problem

15 Methanol and Ethanol

One issue that I did not touch on in the original Guide was the use of oxygenated fuels, particularly

methanol and E85 (both forms of alcohol-base fuels). Both meth and E85 are common ways to

squeeze in more power from a given engine combination. Both fuels are oxygenated, and can deliver

significantly more power provided the engine is tuned to use their respective capabilities. For early

Holdens, this is normally by taking advantage of the increased octane (pump fuel is typically 91RON,

whilst E85 is 105RON and methanol is 109RON) by increasing compression ratio and/or advancing

ignition timing. Bear in mind that a bog-stock grey motor has a compression ratio in the range of 6.5:1

to 7.25:1. As a very rough guide…

Compression Ratio

RON Required

5:1 72

6:1 81

7:1 87

8:1 92

9:1 96

10:1 100

11:1 104

12:1 108

There are however some things to be wary of when running alky in a carburetor. The most

pronounced issue is that E85 requires 25-30% more fuel flow (1.25 to 1.3 times your current pump

petrol flow), whilst methanol requires 100-150% more fuel flow (2 to 2.5 times your current flow).

Provided your fuel pump is up to it, the carburetor itself may not be. Whilst running methanoI is

nothing new to the grey motor racing fraternity, running E85 is. Part of the difficulty in examining what

has historically worked is that a common way to tune methanol is to run the carburetor way, way rich

(i.e. flow much more fuel than is required). This has little downside on power, and is OK for short

duration track work. However, for those hunting efficiency a the same time (say for a daily driver on

E85 or for distance circuit work) a more logical approach is warranted. I will look at each of the Holden

grey motor BXOV-1 carburettor fuel circuits below to give some idea of what may need to be

changed. The information below is thus more a tuning guide, rather than the rough and ready “block

the power valve, wind out the idle screw and double the jet size” approach.

15.1 The Float System

The aim of the float system is to keeps a consistent level of liquid fuel “ready to go” in the carburetor.

The float system contains alloy materials (the carburetor body). Whilst E85 is mildly aggressive to

aluminum and zinc, methanol is quite aggressive (particularly if the methanol becomes wet). Use of

E85 may result in some light white corrosion deposits in the carburetor, increasing the frequency of

overhaul. Methanol however can cause these deposits to become quite heavy, and may require

flushing of the carburetor with petrol prior to storage. Similarly, the brass floats used in the float

chamber are soldered, with the potential existing for attack of the lead or tin by methanol. The

probability of the float unsoldering and sinking exists, albeit over time and with a reduced risk if

flushing is used. The brass float body has some corrosion resistance to E85, though may suffer the

white powdery buildup, especially in methanol service. The float needles are typically Viton tipped,

which has excellent compatibility with ethanol and fair compatibility with methanol.

So just how much fuel do we need? Typically, at wide open throttle, full power, an engine requires ½

pound of petrol fuel per horsepower every hour. A gallon of petrol weighs approximately 6 pounds. As

an example, an engine rated at 350 horsepower will require about (350bhp x ½ lbs =) 175 lbs of petrol

every hour, which is (175 lbs÷6 lbs =) 29 gallons per hour. For a grey motor at the factory 75bhp, this

is 6gph. Running E85, we are thus looking for around 8gph, and for methanol 15gph.

The primary restriction to fuel flow in the float system is the needle and seat assembly (at least inside

the carburetor… we will look at the fuel pump a little later). The standard Holden grey motor had a

seat assembly orifice that was 0.070-0.073” diameter. Most of these original needle and seat

assemblies have failed long ago. The typical replacement part (for example the Fuelmiser overhaul kit

part number SSB-652 for FX-HR BXV, BXOV and BXUV models, SSB-655 for BX models and SSB-

651 for WW models) contains a 0.076” diameter float needle valve seat assembly. Larger float needle

assemblies were available for the Holden red motors, with the following carburetors having a 0.092”

diameter orifice:

Holden EH 179ci engines with manual and automatic transmissions (August 1963 – early 1964,

carburettor code 23-3003).

Holden EH 179ci engines with manual and automatic transmissions (early 1964 – February 1965,

carburettor code 23-3006).

Holden HD 179ci economy (taxi) engines (late 1965 – April 1966) and Holden HR and HK 186ci

economy (taxi) engines (April 1966 – 1968) (carburettor codes 23-3012 and 23-3021).

Holden HD 179ci engines (February 1965 – April 1966). Holden HD (February 1965 – April 1966),

HR and HK (April 1966 – 1968), HT and HG 186ci engines with automatic transmissions.

(carburettor codes 23-3008 and 23-3014).

Holden HD (February 1965 – April 1966) 179ci engines, Holden HD 179ci X2 engines front

carburettor (February 1965 – April 1966) and HR (April 1966 – 1967) X2 engines with automatic

transmissions front carburettor (carburettor codes 23-3009 and 23-3015).

Holden HD (February 1965 – April 1966) 179ci, Holden HD 179ci X2 engines rear carburettor

(February 1965 – April 1966) and HR (April 1966 – 1967) X2 engines with automatic transmissions

rear carburettor (carburettor codes 23-3010 and 23-3016).

Holden HR and HK (April 1966 – 1968), HT and HG 186ci engines with manual transmissions

(carburettor code 23-3020).

HR 186ci X2 engines with manual transmission front carburettor (April 1966 – 1967, carburettor

code 23-3024) and

HR 186ci X2 engines with manual transmission rear carburettor (April 1966 – 1967, carburettor

code 23-3023).

Note that whilst it is possible to recover an original GMH 0.092” needle and seat assembly from one

of these carburettors, the chances of finding one in a non-leaking condition are very low.

The upshot of this is that most grey motor BXOV-1 Stromberg carburettors are probably now running

the Fuelmiser 0.076” needle and seat. To get this needle and seat to flow more, it is possible to

increase the fuel pressure. Interestingly, the fuel pressure can be increased to around 15psi (from the

factory 3½ to 4½psi) before the valve passes... at least on a test bench. However, the assembly is

very susceptible to vibration. Very small amounts of vibration at this elevated fuel pressure cause the

valve to pass. Bear in mind that your typical Holden grey motor is not perfectly vibration free – far

from it. In realistic conditions, the Fuelmiser valves begin to pass at around 7psi. We need a little bit of

lee-way for a running car, say running at 5psi. At this pressure, bench testing shows that the

Fuelmiser valve will flow 7.8gph. Remember from above that we need 8gph for E85, and for methanol

15gph. This means that our Fuelmiser needle and seat will run E85 (just), but will starve on methanol.

Note that it is possible to drill out the Fuelmiser needle and seat from 0.076” to nearly 0.130”.

However, this type of drilling drastically reduces the viton sealing area, and is very likely to leave drill

marks in the brass. This makes the needle and seat very prone to

passing, and is not recommended.

Note that an alternative needle and seat assembly is made by

Genuine Stromberg. The Genuine Stromberg part is a two-ball type

rather than the traditional needle and seat, and is referred to as an S-

jet – see image to the right. The Genuine Stromberg threads (7/16-20

UNF on the carburettor end and ½-20 UNF on the fuel line end) are

identical to the grey motor Stromberg, and the S-jet screws easily in

place. The S-jet comes in two sizes - part number 9564K is made for

¼” pipe, whilst 9564K-BIG is made for 5/16” pipe. Of note, the S-jets are

not made for the standard Holden fuel pipe, which is 5/16” pipe seated

with a 45º double flare. Instead, the S-jets are set up for an 18º seat

compression fitting – see image to the right. This means that a

compression nut and ferrule (part number 9081K for ¼” pipe or part

number 9081K-BIG for 5/16” pipe) is required, as per the image to the

right. To fit the Holden fuel line, the original 45º double flare is cut off

with a tube cutter, and the Holden flare nut removed. The 9081K-BIG

flare nut and ferrule are fitted over the pipe, and then tightened into the

9564K-BIG S-jet. When the S-jet is installed in the BXOV-1 carburettor,

around 1/3 of the S-jet discharge holes are blocked by the float pin

retaining clip. Bench testing of the S-jet shows that it begins to pass at

pressures similar to the Fuelmiser valve - at around 7psi. Using the same lee-way for a running car

(running at 5psi), the S-jet will flow 11.6gph in the BXOV-1 carburettor. This means the S-jet will

happily run E85, but will struggle with methanol.

A solution to the above constraint (especially on methanol) is to run two needle and seat assemblies.

This is done by running two (or three) carburettors – the fuel load is thus split in half (or thirds),

lowering the flow requirement per needle and seat. Whilst this helps with the float system, it does not

help so much with the systems used for mixture control, which we will examine below.

There may be some resetting needed of the float level when first changing to either E85 or ethanol,

typically a very slight level increase. Both E85 and methanol are at the heavy end of the typical petrol

densities (E85 is typically 0.77-0.79, methanol 0.79 and petrol 0.72-0.78). This means the float may

sit slightly higher in alky vehicles, shutting fuel off earlier and giving a low float bowl level.

In short, the float system is unlikely to be effected much by a change to E85, though will be by

changing to methanol, where flushing before storage should be considered. For both fuels, there will

be deposition of white powdery material, increasing the frequency of overhaul. The float level will

need to be increased (albeit slightly) when changing to alky.

15.2 The Idle System

The aim of the idle system, which controls the fuel/air mixture at no-throttle and slight-throttle

operation. There are no additional materials issues in the idle system, as it is made of the same alloy

and brass materials as above.

There are two restrictions to fuel flow in the idle system. Firstly, the idle tube has a very small

“metering orifice” or hole in the end which meters the amount of fuel. For the standard Holden grey

motor, this idle tube orifice is #70 drill (0.0280”). Even though the fuel is flowing through both the idle

tube and the main metering jet, the idle tube does most of the metering (or controlling) of the fuel flow.

This is because the idle tube metering orifice is about half the diameter of the main metering jet (much

more restrictive). Secondly, the amount of fuel/air mixture which passes through the first stage (lower)

idle hole is regulated by the idle needle valve – screwing it in lets less fuel/air emulsion flow (leaner),

screwing it out lets more fuel/air emulsion flow (richer). Note that the idle needle valve has no effect

on the flow to the second stage (upper) idle holes.

It is tempting to increase fuel flow to the idle system purely by screwing out the idle needle valve. To

check this, I wet flow tested the first stage idle system of a BXOV-1 carb at different idle needle valve

settings, with the results as per the chart below. I have then taken the first stage idle system flow

capability and compared it to the standard FB/EK Holden grey motor setting in the chart below (i.e.

100% in the chart below is equivalent to the idle needle valve turned out one full turn, 50% would flow

half as much as one full turn).

From the chart, it is apparent that if we screw the idle needle valve any more than two turns open,

then the system cannot generate any more than 143% flow. This would be OK for E85, but falls short

of the amount of flow required for methanol. We could get cute and drill out the lower idle discharge

hole to get more flow. However, bear in mind that we are only modifying the first stage idle system in

doing this, and not changing the second stage idle system. This means that we could screw out the

idle screw for E85 (or do a little drilling for methanol) and could conceivably get a decent idle, but the

car would stumble as we moved between idle and cruise.

The smarter way to change the idle system is to drill out the idle tube. To check this, I wet flow tested

the idle tube for a BXOV-1 carb at drillings, with the results as per the chart below. I have then taken

the idle tube flow capability and compared it to the standard FB/EK Holden grey motor idle tube in the

chart below (i.e. 100% in the chart below is equivalent to the standard idle tube, 50% would flow half

as much as the standard idle tube).

70

80

90

100

110

120

130

140

150

Softly seated

½ turn open

¾ turn open

1 turn open

1½ turns open

2 turns open

2½ turns open

3 turns open

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1-t

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val

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Idle needle valve opening

This chart is a lot more promising. We can see that if we increase the idle tube diameter from 0.025”

to 0.031” (#68 drill), we are able to flow the 130% required for E85. We could achieve this by

removing and drilling out the tube. Another way is to swap to another tube from the following early

Holdens, which conveniently have a 0.031” (#68 drill) idle tube:

Holden EH 149ci engines with manual and automatic transmissions (early 1964 - February 1965,

carburettor code 23-3005),

Holden EH 179ci engines with manual and automatic transmissions (early 1964 – February 1965,

carburettor code 23-3006),

Holden HD 179ci economy (taxi) engines (late 1965 – April 1966) and Holden HR and HK 186ci

economy (taxi) engines (April 1966 – 1968), carburettor codes 23-3012 and 23-3021,

Holden HD (February 1965 - April 1966), HR and HK (April 1966 – 1968) automatic transmissions,

HT, HG and LC 149ci and 161ci engines, carburettor codes 23-3013 and 23-3007,

Holden HD 179ci engines (February 1965 – April 1966). Holden HD (February 1965 – April 1966),

HR and HK (April 1966 – 1968), HT and HG 186ci engines with automatic transmissions,

carburettor codes 23-3008 and 23-3014,

Holden HR and HK (April 1966-1968), HT, HG and LC 161ci engines with manual transmissions.

(carburettor code 23-3019), and

Holden HR and HK (April 1966 – 1968), HT and HG 186ci engines with manual transmissions

(carburettor code 23-3020).

One issue to be wary of is that the idle discharge holes in the BXOV-1 carburettor are 0.0465”, 0.036”

and 0.0280” (#56, #64 and #70 drill). By increasing the idle tube diameter from 0.025” to 0.031” (#70

to #68 drill), we move from the small idle tube controlling fuel flow to the idle discharge holes having

more effect. This may slightly reduce the flow (mostly from the 0.0280” hole), though should be

manageable.

100

120

140

160

180

200

220

240

260

280

300

0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06

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Idle tube diameter (")

For methanol, the chart shows that increasing the diameter to 0.047” gives us the 250% fuel flow

required for methanol. Sadly, there is no GMH idle tube of that diameter (even the 202ci engines only

ran 0.031” (#68 drill) idle tubes), which means the existing grey motor tube must be drilled out. The

effect of making the idle tube larger than the idle discharge holes will be more pronounced here.

Whilst some compensation will be available for the first stage idle system (via the idle needle valve),

it may be wise to open up the idle tube slightly more than 0.047”.

In short, the idle system is unlikely to be effected much by a change to E85, though will be by

changing to methanol, where flushing before storage should be considered. For both fuels, there will

be deposition of white powdery material, increasing the frequency of overhaul. The idle tube should

be drilled out to 0.031” diameter for E85 (or swapped to the idle tube from the carburetors noted

above), and to 0.047” (or slightly larger) when changing to methanol.

15.3 The Main Metering System

The aim of the main metering system, which controls the fuel/air mixture at mid-throttle (or “cruise”)

operation. There are no additional materials issues in the main metering system, as it is made of the

same alloy and brass materials as above. The main metering system’s fuel flow capacity is controlled

by the size of the main metering jets (or standard FB/EK Holden grey motor having a 0.051” main

metering jet). To get a feel for what changes may be required to the main metering jets, I have wet-

tested a number of jets. I have then taken the jet flow capability and compared it to the standard

FB/EK Holden grey motor jet in the chart below (i.e. 100% in the chart below is equivalent to a 0.051”

jet, 50% would flow half as much as a 0.051” jet).

We can then use the chart above to work out what we should change our jet to, assuming we are

starting with a 0.051” main metering jet. If we were changing to E85, we need 125 – 130% the

standard flow. From the chart, this would mean changing to a 0.061” main metering jet. Similarly, if we

were changing to methanol we need 200 – 250% the standard flow. From the chart, this would mean

changing to a 0.087” main metering jet. Note that I am taking a slightly over-rich reading on the chart

– this is because it is safer to operate a little rich, rather than a little lean.

The chart can equally be used if our jets are other than the standard 0.051”. For example, if we had a

set of twin Strommies which were running 0.045” jets, we can see from the chart that we are at about

75% of the standard flow. If we wanted to change to E85, we would want (130% x 75% = ) 98%. The

chart indicates that we would be looking at 0.051” jets to achieve this.

As a sense check, many historical Stromberg 97 carburettors have been converted to methanol use.

These carbs run the same jets as the BX-model Strombergs we are looking at. The standard

Stromberg 97 jet is a 0.045”, with 0.075-0.082” being a common range for methanol conversion. From

the chart, 0.045” is at 75% of the standard flow. If we wanted to change to methanol, we would want

(250% x 75% = ) 190%. The chart indicates that we would be looking at 0.075” jets to achieve this,

which is in the right ballpark.

So in summary, for our main metering system all we need to do is check our existing jets against the

chart above, then increase to get a flow 125-130% greater for E85 or 200-250% great for methanol. If

the standard 0.051” jet is in the vehicle, then a 0.061” jet should be chosen for E85 and 0.087” for

methanol. There will be some fine tuning required, but this gives us a good starting point.

15.4 The Accelerating System

The aim of the accelerating system is to give a small “shot” of fuel when you initially put your foot

down. Whilst most of the materials in the accelerating system are similar to the above (alloy and

brass), the pump plunger does have a washer at the end of it. The washer is critical to achieving the

fuel flow, as it acts like the rings in a piston assembly. Historically, the washers were made of leather,

which is incompatable with both E85 and methanol (it becomes very hard). Note that the SSB-652

FuelMiser overhaul kit for BXOV-1 carbs also uses a leather pump washer. The ability of the synthetic

type pump washers to survive will depend on what material is used – for example natural rubber is not

compatible, Buna-N is not too bad (though doesn’t always like unleaded fuels) whilst Viton (a

fluoroelastomer) and neoprene are both suitable. The FuelMiser SB-652 (as opposed to SSB-652) kit

is marketed to be suitable for ethanol-based fuels. This kit has a synthetic pump washer, and is likely

to be either Viton or neoprene. It is worthwhile hunting down one of these kits for E85 or methanol

service.

The volume of the pump squirt is determined by how far the pump piston and stem assembly moves

down the pump well bore. This may be increased on Stromberg BXOV-1 carburettors by moving the

pump link from the standard centre position into the outer position (furthest from the throttle shaft

pivot). This will increase the delivery from 0.87mL/stroke to 1.2mL/stroke, an increase to 137% of the

original delivery. This is ideal for changing to E85, though will fall slightly short of the 200-250% we

need for methanol.

Note that the pump volume is changed by the pump link setting only. Changes to the pump stem

spring stiffness, the size of the pump bypass jet and the pump discharge nozzle diameter affect only

the duration of the pump discharge, not the volume of fuel. Whilst tuning these (as per the guidance in

the early version of the Guide) can assist in changing the way the car behaves, they may not fully

cover the lack of fuel likely to be seen when changing to methanol.

So in summary, for our accelerating system we need to be wary of the leather washer pump plungers,

we should set the pump link from the standard centre position into the outer position (furthest from the

throttle shaft pivot), and be wary that we may get some acceleration hesitation if running methanol.

15.5 The Power System

The aim of the power system, which controls the fuel/air mixture at heavy throttle (hills, towing or race)

operation. There are no additional materials issues in the main metering system, as it is made of the

same alloy and brass materials as above. The flow throught he power bypass system is limit by the

size of the power bypass jet. The standard FB/EK power bypass jet is a #65 drill (0.035”). I initially

intended to wet test the power bypass jets, however the results are not reliable, mainly because

a) The jets flow downwards (through the actuation pin hole) then out the orifice in the side. Whilst the

bottom of the jet opens with the actuation pin, the carb body prevents flow out this end. Mocking

up this setup in a test rig (without disturbing the pin) is not easy.

b) The flowrates through a given valves are very dependant on how the actuation pin is pushed –

even a light sideways pressure skews the results.

For this reason, we will need to use a little bit of engineering. Flowrate through an orifice is

proportional to the square of the diameter. We can use this to calculate flow for diferrent orifices

relative to our standard FB/EK power bypass jet, and plot the chart below:

If we were changing to E85, we need 125 – 130% the standard flow. From the chart, this would mean

changing to from the standard #65 drill power bypass jet to a #60 drill. Similarly, if we were changing

to methanol we need 200 – 250% the standard flow, and should change to a #54 drill.

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71

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Power Bypass Jet Diameter (drill #)

As an aside, this graph is also handy if running multiple carburetors on pump fuel. For example, if we

were changing our FB/EK Holden from a single carb to twins, we would want half the flow (50%).

From the chart above, a #71 drill valve is probably correct.

A number of power bypass jets are available for Stromberg carburettors, both factory and aftermarket.

from the Stromberg Carburetor Ltd for Stromberg 97 carburettors.

Jet Size Diameter GMH Part Number Stromberg Carburetor

Ltd Part Number

Standard for

#54 0.0550” 7424565 - EH (179ci)

#55 0.0520” 7420747 -

EH, HD excluding X2, HR (179ci)

HR excluding X2 and S (186ci)

#56 0.0465” 7420490 -

EH, HD, HR (149ci)

HR (161ci) HD normal and

economy excluding X2

(179ci) HR X2 and

economy (186ci)

#57 0.0430” 7424564 - EH (149ci)

#58 0.0420” -

#59 0.0410” -

#60 0.0400” - 9594K60 -

#61 0.0390” - 9594K61 -

#62 0.0380” - 9594K62 -

#63 0.0370” - 9594K63 48, 53

(132.5ci)

#64 0.0360” - 9594K64

#65 0.0350” 7406899 9594K65

FB, EK, EJ (138ci)

HD economy (149ci)

HR economy (161ci)

#66 0.0330” - 9594K66 -

#67 0.0320” - 9594K67 FJ, FE, FC (132.5ci)

#68 0.0310” - 9594K68 -

#69 0.0292” - 9594K69 -

#70 0.0280” - 9594K70 -

#71 0.0260” - 9594K71 -

This shows that for our FB/EK running E85 an aftermarket 9594K60 (#60) jet would be suitable, and

for methanol a #54 jet from an 179ci EH motor (look for carburetor codes 23-3003 and 23-3006). Note

that care needs to be taken with the power bypass jets from the HR Holden 186S (WW-Model). Whilst

these are interchangeable with the BXOV-1 jets, the WW have two Nº.56 drill (0.0465”) holes (i.e.

double the capacity) compared to the single hole jets.

As a sense check, many historical Stromberg 97 carburettors have been converted to methanol use.

These carbs typically a #65 power bypass valve, with a 0.069” power bypass valve common when

running methanol. Using the calculations above, a 0.069” valve would flow 380% more. This seems a

little high, though this overly rich valve has probably been specified as a safe state of tune.

15.6 The Choke System

The aim of the choke system, which controls the air/fuel mixture for cold starting and warm-up. There

are no additional materials issues in the main metering system, as it is made of the same alloy and

brass materials as above, with the addition of mild steel. Mild steel is fairly resistant to corrosion by

E85 and methanol. No modifications are likely to be needed to the choke system.

15.7 Fuel Pump and Tank

The grey motor fuel pump is a positive displacement unit, driven off the camshaft. The alloy body and

brass screen materials are likely to have similar (relatively minor) issues with E85 and methanol as

noted above. Of more of a concern is the factory rubber pump diaphragm and valves. The rubber is

not compatible with alcohols, and should be replaced with either neoprene or viton. Holdenman

Restomotive (www earlyholdenparts.com.au, telephone 0408349185, email

[email protected]) does this type of neoprene-based kit as:

part number 5591844 for 48-215 or FX, FJ and FE Holdens up to engine number L327358, which

had the single acting combined fuel and vacuum pumps,

part number 7950399 for FE Holdens from engine number L327359, as well as FC and FB

Holdens which had the double acting combined fuel and vacuum pumps, and

part number 7420687 for EK Holden through to VB Commodore, which had no vacuum pump.

Note that the fuel tank itself will tend to be cleaned up by both E85 and methanol. For an old Holden,

this can mean that decades worth of crap can be flushed through. A good filter is recommended,

preferably with a stainless steel filter (aftermarket paper fuel filters are sometimes glued internally,

with the glue soluble in alcohols). Whilst plain steel is OK, some fuel tanks (and probably most

Holdens up to the 1990’s) were coated with terne. This is an old anti-corrosion coating of 80% lead

and 20% tin. Terne plate will be attacked fairly aggressively by both E85 and methanol. For long-term

use, it is wise to consider upgrading to a stainless tank. Early Holden stainless tanks are available

from Marty Dean (M&C Dean Fabrication Pty Ltd, 23-27 Gazelle Court Greenbank, Queensland 4124,

telephone: 0421060996).

As we saw above, running E85 we are thus looking for around 8gph, and for methanol 15gph. The

capacities of the genuine GMH fuel pumps for both grey and red motors are shown below:

Fuel Pump Maximum

Pressure

(psi)

Free

Flow

(GPH)

Early Holden (grey/red glass bowl) 4½ 9

Later Holden (blue motor steel can) 3.9 9½

As we can see, we are likely to (just) be able to keep up with E85. This assumes that the motor is not

punching out all that much more power than standard though – add a worked head, some twin carbs

and exhaust and we start to get marginal for fuel. For methanol, the factory pump has nowhere near

enough capacity. There are a number of electric pumps that can deliver the required flow, though

bear in mind that some of these may not be compatible with alky:

Fuel Pump Maximum Pressure (psi) Free Flow (GPH) Facet SS208 or SS171 3½ 14

Facet SS165 5 15

Facet SS148 4½ 24

Facet SS500 or 60104 4 25

Facet SS185 11½ 29

Facet SS501 4½ 30

Facet STS504 5½ 30

Facet IP051 8 30

Facet IP002 4 32

Facet 60106 6 32

Facet SS502 7 32

Facet SS200 9 32

Facet 40222, 40223 or 40237 11½ 33

Facet SS135 6 34

Facet SS503 or 60107 10 34

Facet STC505 7 35

Facet IP007, IP131 or IP220 5½ 36

Facet RTW506 or BTP001 8 40

Carter GP4603HD 6 43

Carter GP4070 6 72

Carter GP4594, GP4389, GP4259 and GP4602RV 8 72

Carter GP4600HP 5 100

Holley Red 10 100

Carter GP4601HP 18 100

Holley Blue 18 110

Holley Black 18 145

Documents

FB/EK Holden Stromberg Carburettion Enthusiasts Guide Addendum 1