Buick 1930 carb

[vintagestevo]

i have a 6 cylinder Buick model 40 which was assembled in Australia.

the car should have a marvel carb but this has been replaced in the distant past with a Stromberg

I've owned the car for five years but it has never run well, it often backfires and achieving a smooth tickover was not possible.

I assumed that another identical carb might do the job but this has made matters worse. I believe as everything else I can think of has been done that it is fuel starvation. Could anyone suggest an alternative carb I might fit?

 

 

Edited November 5, 2018 by vintagestevo
Given incorrect age of car (see edit history)

[edinmass]

Carbking will chime in......and I would do exactly as he recommends. 

[MCHinson]

Can you clarify what year your car is? Also, what brand and model carburetor do you have? I am not aware of a 6 cylinder engine in any 1940 Buick.

[vintagestevo]

The car is a 1930 series 40 with a straight six cylinder engine, 257.5 cu inch

At present the carb I have on it is a single barrel Stromberg 

Thanks for responding 

 

[carbking]

Stromberg made some of the finest carburetors ever made, anywhere, at any price.

 

That doesn't prevent someone from pulling one from under the workbench that is incorrect for the vehicle, or the carburetor being incorrectly set up for the vehicle in question.

 

Exactly which Stromberg are you dealing with?

What type of fuel delivery system? If pressure, how much pressure?

Where is the backfire? Through the carburetor, or through the exhaust?

 

And GUESSING (never a good idea, but I do it anyway): If you have one of the SF series Stromberg carbs, the SF series use an inverse idle circuit. Adjusting "IN" makes the mixture richer, "OUT" makes the mixture leaner. If the screw is completely closed, that would be the richest idle setting. The high speed adjustment (if present), is the conventional in lean, out rich. The suggested initial setting was 2 1/2 complete turns from lightly seated.

 

IF YOU HAVE ANY OTHER STROMBERG THAN AN SF SERIES, DISREGARD THE ABOVE!

 

And you mention having done everything else, but you suspect fuel starvation. No offense intended, but valves which are too tight will mimic this symptom, as will a defective electronic distributor conversion. In fact, if an electronic conversion is done, ALWAYS the first test is to UPGRADE back to points/condenser.

 

Jon.

Edited November 5, 2018 by carbking (see edit history)

[vintagestevo]

Many thanks for your response, it has an electric 6v su fuel pump, with original an distributor

I do not know the pressure being delivered, other than it shoots out, so that is a path to investigate.

Although the valve clearances are ok, it might well benefit from an inspection of the valves.

If you can bear with me I will upload a pic of the carb tomorrow which has very little to identify it, there is quite a time difference as I am in the UK

Steve

 

[Spinneyhill]

If it has an electric fuel pump, are you sure it is not drowning? i.e. the pressure is too high and it is flooding because the carburettor float is not big enough to push the needle valve shut. It probably only wants 1.5 psi.

 

Backfire through the carburettor could be a sticky valve?

 

Why do you think the problem is fuel?

 

Is the distributor shaft wobbly in the distributor? This will cause random timing changes.

 

The original fuel pump was an AC 855401, a type B pump.

Edited November 5, 2018 by Spinneyhill (see edit history)

[carbking]

This link explains the Stromberg type SF carb, and there are pictures that will help you with the identification.

 

http://www.thecarburetorshop.com/Stromberg_SF_carburetors.htm

 

Jon

[vintagestevo]

T

[vintagestevo]

Thank -you for your replies, I can get the pressure tested, and I too suspect a sticky valve as the manual suggest this as one of the principal causes of uneven running.

The distributor is quite firm and runs freely on its advance and retard mechanism.

The car at the moment starts on the choke and accelerates to high revs, but  with the choke -in when hot, the car runs very erratically, basically when you take your foot off the gas it will as like dieh

After a period of backfiring out the exhaust.

The exhaust is quite clear with no smoke visible.

If you pull out the choke when running hot the engine will also die. I'm sure this is normal

We have cleaned and blown through carb, and also purchased an enlarge main jet, checked the spark, rotor etc

The electric su pump used to run through and mechanical pump but I've rerouted it straight to the carb as I suspect some debris from its old diaphragm was working its way into the carb.  

Jon thank you for the link it is indeed a treasure trove of info.  I've upload a pic of the original replacement carburettor, and studied it, it is a Stromberg Holden.

I frankly do not know what difference this makes only that Holden manufactured the bodies on the Australian assembled cars.

Any more help greatly appreciated.

(I will upload a pic of the car)

 

[carbking]

I knew I should not have guessed!

 

The pictured carburetor is a Stromberg B series DOWNDRAFT. The original Marvel on a 1930 Buick 40 would have been an UPDRAFT, as is the Stromberg SF series.

 

So, either the engine is from a later Buick, OR, more likely, someone has flipped the intake to junk the "marvelous" Marvel, and replace it with a real carburetor, in this case a downdraft.

 

So the first order of business would be to determine the year and size of the engine; either verifying that it is the original with a flipped manifold or ???

 

The B series Stromberg is also an excellent carburetor IF this particular one is suitable size-wise to the engine. No need to speculate further until the origin of the engine is known. However knowing the fraction in a circle on the bowl (center) casting will help us determine if the carb is applicable once we know the engine origin. The fraction should be something like 1 3/32 or 1 5/16 or something similar. This is the I.D. of the main venturi, and is the main consideration in adapting a non-original carb to an engine. Also need to know if this carb has the external adjustable main jet (would be a turnable knob pointed up at a 45 degree angle on the edge/bottom of the bowl (center) casting. I cannot tell from the picture. Or, take pictures of the carb from all 4 sides.

 

Jon.

 

[vintagestevo]

Thanks for your reply Jon, the flipped manifold certainly explains it, we thought perhaps it came with this carburettor for a moment!

I've done some digging around my paperwork that came with the car, The engine no. is 226568 but as yet I cannot find any record for 1930 series 40 engine numbers on the net.

But I do have letter from the last owner in (3 in total) explaining that they replaced the marvel with a down draft carburettor and basically the old parts were under the seat. I personally believe the engine to be the original as it was partially restored over here by the previous, now deceased owner, and I know he didn't change it, but of course that still leaves 70 years unaccounted for.

If that is correct the cu in is 257.5, I understand this to be 4219 litres, wow.

The stamping on the bowl it is problem, please see pics, I have looked all over bowl without finding the circle stamp. It has an adjustable main jet  on the front

I Much appreciate your effort Jon

Steve

[Vintageben]

Ah that Buick has come from Australia, so when the old carby had a problem someone would have said to the owner " Just flip the manifold, throw a Holden carby on it and she'll be right"  well maybe not always. Now I'm not sure of exactly which Holden this came off as I'm not a Holden man but I think it will be either what they call the Grey motor( 132.5 to 138 cubic inches) or the red motor(173 to 202 cubic inches), I'm sure you could narrow it down with a bit of research. Either way these engines are a fair bit smaller than yours so unless the idle jets are changed I'm guessing it will give you problem. Anyway you may want to hunt down some Buick owners down here that may know more about this modification or just get a carby you know will work on that engine, Ah that sounds all so easy when said quickly

[vintagestevo]

The idea that the carb was made for another Holden car sounds right to me, I am hoping that Jon will be able with the sparse info I've been able to give, to shed some light on the carburettors suitability. The car has never run with much acceleration or pull since a brought it, but in fairness it did not die on me until when visiting our local garage a mechanic decided he could make it run better by adjusting the carb---it has never run the same again, but know he meant well. 

Thanks for your reply

Steve

[1939_Buick]

On 11/6/2018 at 8:22 PM, vintagestevo said:

I frankly do not know what difference this makes only that Holden manufactured the bodies on the Australian assembled cars.

Holden made bodies for a lot of brands in the 1920 & 1930's. Taken over by GM in 1931.  Then made/assembled cars for GM and other brands.  Finally in 1948 manufactured a car with the Holden brand.  Production ceased Oct 2017

https://en.wikipedia.org/wiki/Holden

 

Carb's from the Holden red motor (149/179/186ci) are a common replacement on old 1920's 1930 's engines.  While originally fitted to an engine with a smaller ci capacity old engines have low compression, poor volumetric effecticency and probably rev lower.

https://en.wikipedia.org/wiki/Holden_motor

 

As post 7 it may not be the carb.

Where is the car now?

[vintagestevo]

Thank-you for your reply, I have checked the net using images and have found the carb on engines that looks identical on a 6 cylinder grey engine, amongst others. I'm just wondering whether the stamp on the carb saying aviation corp might indicate that this carb was made during war II when they made these carbs for aeroplanes and boats, possibly.

The red engine carbs although similar look a bit different though

 it could as you say be other problems such as fuel pressure, but I am keen to try another suitable carb If I knew the best option, that red engine one looks promising. The car is Christchurch UK not New Zealand unfortunately

Any advise you or others give is very helpful, I have never used a forum before  but I have learnt a great deal from these posts

Steve

[carbking]

Well - the Bendix-Technico kind of removes me from helping with this carburetor. I simply do not have the resources.

 

However:

 

Bendix Aviation was/is a conglomerate. Until they were partially disassembled by the anti-trust do-gooders, Bendix Aviation was the parent company of both Stromberg Carburetors and Zenith Carburetors. Think of the relationship that Bendix is to Stromberg as G.M. is to Buick. And while both Stromberg and Zenith DID build aviation carburetors, the ground division of both Stromberg and Zenith was much larger than the aviation division. Do not get side-tracked by the "aviation" in the Bendix name.

 

Stromberg had "sister companies" in other parts of our world from the USA. Bendix-Technico is the sister company of Stromberg in Australia.

 

I am the current caretaker of the remaining Stromberg-USA drawings, manuals, etc. but I have virtually NOTHING on Bendix-Technico.

 

On USA-built B-series Strombergs with the externally adjustable main metering jet, the operational range of the adjustment was from zero to 5 turns. The suggested starting calibration was 2 1/2 turns and then tune from there ASSUMING THE CARBURETOR INTERNALLY IS CORRECT FOR THE ENGINE. Since you have this carb, I would suggest trying to adjust this calibration, to see if you can improve performance. Zero turns is very lean, 5 turns is maximum fuel richness.

 

Maybe someone else has more information than I on Bendix-Technico.

 

If it turns out you wish to change carburetors, it will obviously depend on what is readily available in your area without paying large shipping charges. If the vehicle were in the USA, AND the owner did not require a "period" carburetor (one from the early 1930's), I would suggest a Carter type YF used on a 300 CID Ford 6. Excellent carburetor, and common as dirt.

 

Jon.

[vintagestevo]

Thank-you Jon. I will do as say and if I've still got my mind set of replacing the carburettor, I'll try the Carter.

many thanks

Steve

 

[Curti]

Jon,  in reference to the small blank spot near the fuel inlet on Strombergs ,  what do  the numbers and letters designate, other than the venturi size ?

[carbking]

Curti - not a "one size fits all" answer.

 

Referring to USA-built Strombergs:

 

Many have the internal venturi size cast into the bowl casting.

Some have the main metering jet I.D. stamped into the casting.

Most will have the part number for the BLANK CASTING cast into the casting. This is not a part number most will find anywhere. It is an internal number for a casting prior to machining.

 

Beginning about 1935, Stromberg stamped the "code identification number" of the carburetor into one of the castings. From my website:

"Stromberg

The following applies to Stromberg-USA carburetors, and does not apply to Stromberg carburetors produced elsewhere:

Stromberg began stamping a ‘code’ number on virtually all O.E. (original equipment) carburetors beginning in 1935 up through the end of production in 1974. Most of the carburetors produced in the late 1930’s were stamped on the throttle body. Others were stamped on the airhorn. After 1940 this trend was reversed, and most carburetors were stamped on the top surface of the airhorn along one of the edges. Replacement carburetors produced during this period were generally identified by tag only (although a few replacements were stamped). The stamped ‘code’ is in the format ‘ccc-nnne’ where ccc is a one, two, or three digit code representing the company for which the carburetor was produced (ie 2=Ford, 4=Chrysler, 7=Buick, etc.); nnn is a one, two, or three digit number representing the next sequential number of carburetor sold to the company in ‘ccc’; and e is a letter (if present) representing the engineering change status of the carburetor. An example would be 7-69A which is decoded as 7 (Buick); 69 (the sixty-ninth type of carburetor sold to Buick – this one fits a 40 series in 1949); and ‘A’ meaning one engineering change to the original specifications. A second change would be 7-69B. Stromberg used both rectangular (held in place by a screw) and round (riveted in place) tags during this period, on those units which were tagged. 

Stromberg carburetors produced prior to 1935 can easily be identified as to type, as it is cast onto the carburetor; however complete identification is impossible unless one has prior knowledge of the carburetor being identified; and can be quite difficult and time consuming for even someone with the original prints."

Jon.

 

[Curti]

Jon,  how would you decode these two ?  Of course they are both EX-32  with a 1 3/8 venturi.  Both are  35-36 Auburn supercharged.  It is my understanding that the 1 3/8 venturi is supercharges Auburn only.   How yould you decode the other numbers ? 

[carbking]

These numbers cannot easily (if at all) be decoded. They are casting numbers for "blank" castings, prior to the casting being machined.

 

The best example I can give would be throttle bodies from Rochester 2-barrel carburetors for 1957 Pontiac tripower.

 

Front - no idle screws, 1/8 inch pipe vacuum port

Center - idle screws, 1/8 inch pipe vacuum port

Rear - idle screws, no vacuum port

 

ALL have the same casting number.

 

I am unaware of any EX-32 other than the supercharged Auburn that use 1 3/8 venturii. However I have not checked the prints on all of the EX-32's.

 

Jon.

 

[Curti]

From the books that I have, no  car other than a S/C Auburn used an EX-32 with a 1 3/8 venturi.  The Auburn judges all know about the 1 3/8 venturi, and look for that.  The other numbers are just a curiosity. 

There are minor differences in these carbs, maybe the number differences have to do with that.