41 Super stumbels

[Ken Lobsinger -Rejuvenated]

My 41 Super Convertible stumbles every time I get it started and am letting out the clutch in either 1st or reverse.  I am an expericed standard transmission driver, and know I am giving it enough gas without racing the engine.  I am nearly certain I saw a thread about this in "Me and My Buick", but can't find it now.  It did before pulling the oil pan, so I don't think it is something that I did during that process.

 

Your ideas about the problem and any viable solution are welcome.

 

Thanks to all of you.

Edited August 23 by Ken Lobsinger -Rejuvenated
spelling (see edit history)

[EmTee]

Does this problem happen only when engine is cold, hot, or always?

[Matt Harwood]

First, what type of carburetors do you have--Stromberg or Carter? Have you tried adjusting the mixture screws on the forward carburetor? Both too lean and too rich can cause driveability issues, so getting it right is important. Adjust them in 1/4-turn increments (both screws the same amount in the same direction) and see if things improve. Turn the screws clockwise (tighten them) to remove fuel, turn the counter-clockwise (loosen) to enrich the mixture. A good baseline is to turn them all the way in until they just lightly seat (don't crank them tight) and then back them off 2 to 2.5 turns. Then adjust from there.

 

Please report back and we'll see if we can help.

[Pete O]

Another thing that can cause stumble on take-off is an accelerator pump that's gone bad.  The seal on the pump piston could have crumbled from the ethanol in today's gas.

[carbking]

Probable causes:

 

(1) distributor advance mechanism not functioning

(2) vacuum leak

(3) idle mixture control screws set too rich (causes puddling in the intake)

   (3-C) Carter adjustment range 1/4 turn to maximum 1 and 1/4 turns (3/4 turn recommended)

   (3-S) Stromberg adjustment range 3/4 turn (recommended) to maximum 1 and 1/2 turns

 

Possible causes:

 

(1) defective accelerator pump - TEST by starting engine, stopping engine, remove air cleaner, open choke valve, work throttle to WOT while looking down carburetor throat. Two streams of fuel should appear. If yes, pump is good; if no, work the throttle again, sometimes an air lock develops in the pump cylinder. If no fuel after 2 operations replace pump. If pump must be replaced, leather is superior (opinion) to any artificial material).

(2) non-functional choke 

 

Jon

[Ken Lobsinger -Rejuvenated]

Guys... Thanks for the imput.   This stumbling occurs hot and cold.  I bought the car with a Carter Front carb and Stromberg in back (stange, I know).

I had the carbs rebuilt by a local guy, using kits I purchased from Daytona Parts, on recommendations from Automobilia, so I would think that the acclerator pump should be good.

I have not done any adjustments to the carbs yet, but hope to over this weekend.

 

Carbking - I really appreciate the specific instructions you probided.

Thanks to all.

[carbking]

Ken - I am NOT going to categorically state that set-up will not work; but I am going to say it is certainly suspect.

 

Carter carbs are available.

 

Stromberg carbs are available.

 

When I see something like this, I wonder if the carbs would be right for the engine, if both were the same brand; or did someone just install what was on the shelf? What else has been modified?

 

At this point in time, I would forget tuning, and start verifying engine components!

 

If everything else checks out, I would suggest looking to see if the original progressive linkage is being used.

 

Then, I would determine if the front carb is CORRECT for the engine.

 

If it is, I WOULD COMPLETELY REMOVE THE REAR CARBURETOR AND REPLACE WITH A BLOCKOFF PLATE!

 

The engine will run on the front carburetor, and even drive up to ??? MPH, certainly enough to sort the engine.

 

If everything is worth saving, then look for a MATCHING Carter to match the front carb.

 

Jon.

 

 

[Ken Lobsinger -Rejuvenated]

Jon,  Thanks again for the expert coaching.   If you were not 900 miles from me, I would be at your door.

 

The stumbeling started after the carb rebuild.  I did that eventhough the car was running well, because it was in a collection in TN, and may not have been started in 35 years.  That was supported by the varnish in the fuel lines and tank.  So despite the fact I rigged a temporary gas supply and got it running, I was afraid they carbs would fail at the most undesirable time if I didn't rebuild.  If I can get it running well with the two carbs I have that is objective.

 

The linkage looks identical to the diagram in the manual and the Master Parts list.  On reinstallation I may have allowed a very loose trunnion (part 1314082) to turn 1 or 2 rotations where it connects to the front carb.  I can experiment with that adjustment.  See attached diagram.

 

ENGINE COMPONENT VERIFICATION:  Obviously at least one of the carbs is wrong.  To this point, I haven't found how to determine the correct carbs, (front & rear).  

What are the implications of  going all one brand of carb or another?  I have found your "addendum" on identfying Carter AFB Carburators on Jalopy Journal.  If you can, please share any differences in the process of identifying Stromberg carbs.  (vin tag attached)

 

Here is what I found when I removed the carbs for rebuilding:  

Carter (front carb):  I have no idea which is the model number of this carb.

The climatic control has 170 P 76S is embedded in the black plastic cover.

Pat: 2174313

0436

1-324 

7-121 (on the throttle plate

On the bottom i saw 146-133

 

Stromberg (back carb)

On the base that bolts to intake:  382260 R 6

In a circle cast in the body, 2  4578       15 

                                                                      16

In cursive written vertically on the outside "Aerotype"

Also found "7-43-A"

 

I will spend some time with your addendum and the hood open over the weekend.

It seems to me that if it ran well originally with the blended carb setup, I should be able to get it back to that, and save the money of replacing the at least 1 carb.

Your thoughts and advice are eagerly welcome.

 

Thanks, 

Ken

M: 972-754-0344

 

PS: There is now a page on AACA.Org  listing vendors and suppliers of old Buick parts. Mr. Earl is eager to add pros to the list: You may likely have to scroll down to see the list.

Helpful Web Sites, Vendors and Services.

[carbking]

It is impossible to identify the front carb (Carter) from the posted information; if you will get the number on one of the metering rods, perhaps I can get close.

 

The Stromberg carb posted is number 7-43, which is correct for a rear carb on the 1941 series 40 and series 50. The "A" following the 7-43 simply means the carburetor has evolved through a minor engineering change.

 

The matching Stromberg front carb would be a 7-42.

 

The car should run fairly well up to a certain RPM ON THE FRONT CARB ONLY. Check my previous post.

 

As the rear carb is basically a dumper carb, you MIGHT get by. And, you might not. Compare the cost of either of the carburetors to the cost of rebuilding an engine.

 

EDIT: And just for grins, check out Ebay 365150976235

 

Jon

Edited Tuesday at 10:45 PM by carbking (see edit history)

[Ben Bruce aka First Born]

Is the carburetor "heat valve" operational.?  The valve [ gate/flapper] that directs exhaust against the bottom of the intake .

 

  Ben

[Ken Lobsinger -Rejuvenated]

Jon,   I will look at the rods for numbers.  Is it possible that the model number apprears on the surface of the thoat where it connects to the manifold?  I am not adverse to removing it for a look.

 

So you've got the from the exhaust collector up to the and including an air cleaner for $500 obo?

How about a Stromberg Front carb only, or a Carter back carb.  

 

Again, I am north of San Antonio, 900 miles from you.  If you've got something I can use, out of respect for your consultation, I would like to buy.  Would you agree to a a UPS Pick-up?

 

[carbking]

There are no identifying numbers on the carb, other than the tag.

 

The metering rods are close to being unique, so that number will get us close. You might also measure the main venturi on the front carb. It should be either 7/8 or 1 1/16. Physically, the 248 and 320 carbs can be interchanged (same bolt pattern). 

 

If the main venturi is 7/8 that will tell us we have a 248 carb, then we just need to determine if 1941 or 1942. The metering rods will help with that.

 

I have a better chance of having the rear Carter than the front Stromberg.

 

The junkyards could sell the primary carb for other than the compound carburetion, as it is a complete carb. Thus more rear carbs, both Carter and Stromberg have survived.

 

The compound carburetion unit I have on ebay is priced as it is because of condition, and its in the way! I would make more money by removing the air cleaner and the 2 carbs and selling them individually, and scrap the rest; but I really hate to do that. Not saying I won't. We are downsizing (the kids don't want the carburetors  ), and have already recycled more than 25 tons of more common carbs this year. The recycler is 8 blocks away. Something as heavy as the compound carburetion, I need help lifting, but just carbs pretty easy to throw on the trailer. Have already recycled about a dozen bare factory tripower intakes. They are heavy, and they take up room. I try to sell the stuff first, but if it doesn't sell at wholesale prices, then..............

 

And while I appreciate your comment about buying from me (and yes, I am in business); the consultation and advice given on this and other forums is my way of paying back, absolutely no obligation is expected. And besides, some will tell you the "free" advice is worth less than you paid for it!  

 

Jon

[Ken Lobsinger -Rejuvenated]

Do you want to be on the AACA Buick parts list?   If you decide to sell just the carbs, please keep me in mind.

[carbking]

On 10/2/2024 at 5:56 PM, Ken Lobsinger -Rejuvenated said:

Do you want to be on the AACA Buick parts list?   If you decide to sell just the carbs, please keep me in mind.

The more places we are listed, the better, thanks.

 

As far as the carbs are concerned; the cheapest way to buy them is the complete assembly. If I have to manhandle that thing around and take it apart, I get paid for the effort  as well as the merchandise!

 

If you get the number off of the Carter metering rods, will see if I can match a Carter for you.

 

Jon