FB/EK Holden Stromberg Carburetion Enthusiasts Guide

[Harv]

Ladies and Gents,

As promised, attached below a link to a the FB/EK Holden Stromberg Carburetion Enthusiasts Guide (with thanks to those on the forum who commented). It contains:
•   historical information, such as which carburettors and fittings were fitted to different model Holdens,
•   practical information on identification, disassembly and reassembly of early Holden original and replacement carburettors, and
•   guidance on tuning, replacement parts and overhaul techniques.

It contains answers to many of the questions that seem to come up routinely on most of the early Holden forums:
“What jets should I run in my early Holden, and where do I get them from?”
“Why is my Stromberg carburettor running so poorly?”
“How do I set up twin carburettors on a grey motor?”

Whilst it is written with FB/EK Holden BXOV-1 carburettors in mind, it equally covers the red motor BXUV/BXV carburettors (through to HR) and has a smattering of info on the WW Strombergs from HR Holdens.

http://www.scribd.com/doc/68315221/Carburettor-Guide

Cheers,
Harv (chief apprentice carby fiddler).

[Trevor_B]

Hi Harv,
That's an impressive piece of work, lots of effort and detail.

I tried to download it but it requires Facebook.... and I don't have a Facebook account and don't want one - have seen too much crap go on as a result of that site.

Can you provide another link or if possible please email it to me at blackct@optusnet.com.au

Many thanks,
Trevor_B

[Harv]

Trev,

You got email  . It's a 5MB pdf file though (smallest I could make it) - apologies in advance for clogging your inbox.

I don't have FaceBook either... spend enough time on a 'puter (and not enough in the garage) as it is.

Cheers,
Harv.

[jack_fc]

I had a problem with the Strommy on my HQ - problem diagnosed and remedied thanks to Harv's excellent Guide 

Harv, you're a champion, mate! Thanks heaps for all the time and effort you have so obviously put into this...

cheers, jack

[OldGMHolden]

G'day Harv,
I've been having a look at your Carburettor Guide, and it will be very helpful to many, many enthusiasts. Well Done!
It's a shame I can't download it as I don't have a Fleabook account.

However, having been a Torana owner/racer from the very early days, I noticed a few tiny discrepancies regarding the side-draft (Zenith) Strombergs.

QUOTE "Zenith Strombergs were fitted to LC Holden 161S GTR-XU1 161S engines (triple 1.5” 150 CDSside draught), LJ Holden 202 XU1 engines (triple 175 CD2-S side draught) and HB Holden BrabhamToranas (single 150 CD sidedraught)."UNQUOTE

Triple 1.5" were fitted only to LC GTR XU1's (186 c.i.)
LC GTR (2600S) 161S's had a 2 barrel down-draught, and there were no 161 XU1's

HB Brabham Toranas had twin 1.5's.
HB Series 70 had a single 1.5.

Cheers,
Gaz

[Harv]

No worries Gaz - the Zenith Stromberg reference I used was the same one that had WW Strombergs on HQs... Many thanks for picking up my error.

If you'd like a PDF copy, PM me an email address and I'll send it through.

Cheers,
Harv.

[spanner]

I had a LC 4cyl Deluxe Torana 2 door and it came fitted with a 150cd. In fact the motor (complete with carby) is still in the back shed.
Graham

[Stewy]

Hi Harv would this be any use Ebay Item #290635259329


Cheers Stewy   

[Harv]

G'day Stewy,

Many thanks for pointing this one out. It would be a great reference. It covers another 10 years after the book I have, so would probably be good for the (longer) list of carb numbers (I could update the list in the Guide). I gotta admit though that my interests have now swung over to crashboxs, so will have to invest the cash in manuals and parts for those.

Wonder if the manual owner would photocopy the carb listing for me? Can only ask I suppose.

Cheers,
Harv.

[NES304]

This carby off a grey the same through the grey motor range?

[Harv]

G'day Nes,

Small changes were made to the main discharge jet, power bypass jet and needle/seat diameter, mainly for the auto EKs (see the table on pages 24/25 of the document). Other than that they were identical across the grey range.

Having said that, the changes are not huge... you would notice more difference between a "never been touched" and an "overhauled" carb than you would the above changes (IMHO).

Cheers,
Harv (chief apprentice carby fiddler  ).

[Rod]

Hi Harv,

Sorry to bring up an old tread as I know you are well into your next exciting guide - Normans.

I am still in the process of refining the tuning of twin strommies on a grey and often refer back to this guide. Because I am having trouble in the fine tuning (which I will refer to in another tread) I thought I would investigate what carbys I have installed. Yes they are BXov-1's and the internals as far as jets etc are the same. However on close inspection I noticed that a difference in the castings which I am unsure is contributing to my issues.

One is USA and marked 1 1/32 with 385038 with a small 2-1 just above this identification. The second one is Australian and marked 1 1/32 with 385038 with 1-1..

This then had me thinking. I checked all the spares I have and this casting holds true. Are you aware of any internal differences between the USA and Australian made carbys other than the jets etc... I have a little theory that maybe the internals are a little different to the issues I am having. I think the USA made ones would have been for the FX and possibly FJ's as the processes of producing them hadn't been set up in Australia (no this isn't going to be a Canadian grey debate) while the Australian made came on line for the late models. I am wondering on the internals as the FX and FJ had 50 mains while FE onwards (for greys) had 51. The reason I query this is the USA made carby I have in the twins is running slightly rich in comparison to the Australian one while all the internals as noted above are the same and hence I am having difficulty in the fine tuning. I will highlight the issues I am having in another thread.

What are your thoughts on your investigations?

Cheers

Rod

[Harv]

G'day Rod,

I haven't got my Strommie factory manuals in front of me at the moment, though having said that 'm not aware of any differences in the internals. The factory manual has separate info for the Aussie and US Strommies though... there may be slight differences say in venturi radius but hard to tell without measuring.

There do seem to be differences in the vacuum available to the two carbs in most twin set-ups. There is probably a reason for this in the realms of "inlet pulse theory". I got as far as buying a book on "the scientific design of inlet manifolds", starting reading and even I gave up (the book is still on the shelf with a bookmark in it  ).

How can you tell that one carb is running richer than the other? I assume you're getting plug fouling, and only on 2 outer cylinders? I'm guessing the carbs have been balanced with a gauge so that vacuum is even?

Some food for thought:
a) One way to check if it is a manifold issue is to swap the carbs over and see if the problem goes "to the other side".
b) Anohter test is to swap on another carb and see if it changes.
c) How confident are you of the jets being the same (assuming this is an cruise/part throttle richness)? If both jets are brand-new then maybe not an issue. If they are reused, then it is possible someone has run an oxy tip cleaner through them. I've got a set of pin gauges here if you ever wanted to measure them.
d) Is the power bypass jet on both carbs new? Sticky springs in the older jets can make them leak.

Cheers,
Harv

[hsv-001]

Harv, thanks for all your effort . In most fuel air mixing problems its something basic . Absolutely correct about the oxy tip cleaners I've been using them for decades but they will also give a idea of jet size . When I was running multiple carbs I struggled to get even airflow right across the rev range and more often than not this is most evident at idle as throttle bodies are not matched properly on the linkages and therefore cause exess air and the mixture screws become redundant . When the throttle is open and at an even rev. it is the main metering jets that need to be matching and of the correct size [assuming even air flow]. When the throttle is depressed it is the pump plungers and power valves that must work evenly, and finally on the release of throttle the by-pass metering tubes and jets. It is important to note that a carb. is built[designed] to be most efficient at a specific air flow range [ie.350 holley = 350cfm] . Larger cams can reduce cfm at low revs thereby reducing the ability of the carb. to atomize the fuel [too rich at low revs.]. An example of this is the x2 , where the main jet size is not smaller but larger when running twins, the reduced air flow meant less atomization. My advice, take it or leave it, is to take a long look at the throttle bodies and the manifolds first,then chech the rest.

[Rod]

Thanks for your responses fella's.

Just to clarify a couple of things Harv. The Jets (Mains and Power) are brand new out of the packet. As for the indication of running slightly rich, I haven't read the plugs knowing what you have said in regards to modern fuels. I used the Colortune which allows the user to see into the combustion chamber and see the color of the spark at ignition. The theory follows that of a school science class when lighting bunsen burners (remember all those years ago?). If the flame is Yellow its i running Rich (ie: on the bunsen burner the collet is close reducing oxygen - this is why it is called a saftey flame as it can be seen). If it is Blue (collet open) it is running correctly. This is taken from the intructions which I have a copy of -

Yellow Indicates a fuel / air mixture which have excessive petrol content (rich).
Like a candle flame - producing more light but less heat.

Bunsen Blue Indicates a mixture which is correctly proportioned.

Whitish Blue Indicates a mixture which has less petrol content (lean)

The instructions which come with the colortune are excellent and gives theory behind tuning carby's, correct air fuel ratios etc.. If you would like a copy I could email it to you.

I use a unisync to balance the carby's but as I have said I am unsure if this is correct because the front carby causes the motor to labor and if held in place long enough stall. I am thinking of purchasing a flow meter which I have seen on ebay which supposedly is used for balancing carbys but doesn't rely  on vacuum.

I will follow your suggestions of swapping carbys from front to back and then swap another in etc... and report back if I have any success. I suppose the question is should I be swapping a USA or Australian one into match the other? Like for like I would imagine.

Harv it must be about time you are elevated to legend status. Thanks for all the work you have been putting into the guides. The are fantastic and have offered a valuable resource to many.

Cheers

Rod

[Rod]

One other thing I forgot to mention is that I only have one carby hooked up to the choke and this is the rear carby. Interesting is that I don't have to use the choke in the mornings even in cold Ballarat. This has remained the same even after jetting down to 44's.

Also I have the vacuum advance hooked up to the front carby. Would this effect the vacuum on this carby and hence effect the syncing process on this carby. ( when l last checked the vacuum advance it was not faulty). When I swap the carby's I suppose I will have a clearer picture.

Cheers Again.

Rod

[Harv]

Rod,

It's not unusual to not need the second choke (wind the idle mixture up high enough with one carb and you don't need it for singles  ), but make sure the unattached one has the chake plate wired in the same position as the "off" position of your other carb (and not dangling in the breeze).

Vac advance is OK (there is no flow in that line), unless the diaphragm on the advance unit is shagged. Disconnect at carb, suck the line and put your tongue over the end - if it holds vacuum against your toungue, the diaphragm is OK. Wash out that special "vacuum advance" flavour with VB  .

Cheers,
Harv

[Rod]

Thanks Harv. I will double check the vac advance again on the weekend along with your other suggestions. The second carb choke is held wide open so thats someting else to tick off.

Without taking the carbys off I had another play around tonight with the syching / balancing and came across something bizarre. Before doing so I double checked using the colortune and I am not as convinced as much now that the rear carby is running rich. I took some video so i will check this.

Because I couldnt synch with definite confidence at idle I thought I would try it at part throttle so i could get more suck.The following was happening - the suck was more pronounced on one eventhough at idle they were what i thought in sync. So i balanced them at part throttle and the garden hose technique confirmed this I think. When I went back to idle the second carby was showing more suck. Go figure. There is some mismatch somewhere and I can't help not thinking about possible different internals to the USA made and the Australian one. At very least there are some differing characteristics between the two somehow.

Anyway enough from me now as I have bored you enough. If i have any success over the weekend with the carby swaps etc that you have suggested I will report back.

Cheers

Rod

[hsv-001]

Harv , I have a question relating to twin down draft strommy size and jets . Since calming my red motor down many years ago have only been running 1 single 1 5/32 and have never had any problems , the standard manifold is port matched to a very worked head but the full race cam now resides on the bench . The flow is great and I have never had issues up to around 85 mph . As the HR x2 ran 1 5/32's I was thinking of just building another matched to the one I'm already using .My reasoning being that there shouldn't be a great deal of difference if jets and power valves ect. are the same .Of course the manifold flow may be different and the amount of fuel through two accelerator pumps would have to be addressed but I think if I tuned the carbies on the single manifold first then put them on the twin using the long stroke of the accelerator pumps that they as with the x2 could only run slightly lean due to the air speed down the venturi's thus less bowl pressure. If this is the case I will change the jets up , I'm guessing somewhere between 52-55 . Anyway going to give it a go .Haydn

[Harv]

G'day Haydn,

Both the HR and HD X2 motors ran the smaller 1 3/32" twins, with the 1 5/32" used as singles. Even with the smaller carbs, jetting needs to be pulled down (main metering jets were 0.058" on the singles and reduced to 0.055" on the twins).

No harm in wet-running them on the single manifold to start with - this will let you set up fuel level and check all is working OK. Much easier trouble shooting a single than twins.

Once they both run OK, bolt them up as twins and drive. If you find it is boggy as hell, you may need to neck the venturis down with restictors. Frank Whitby can make you up a set to suit the 1 5/32" throats... he makes a nice product. Once you're happy with the bog, lean the jets down. You're probably right in somewhere between 0.052" and 0.055".... just need to be mindful of avoiding lean-out at cruise.

The accelerator pumps should be OK - overly rich will still accelerate OK, you will just get a puff of smoke out the exhaust when you put the boot into it. Can always adjust the pump stroke if it becomes a big deal.

Cheers,
Harv