39 Carb

[Guest 39Time]

It was a long, mild winter. Once a week, I start up my car to keep the battery charged, and the fluids moving. This last winter though, I realized it was time for a carb rebuild. She was smelling kind of rich, and was blowing black smoke out of the tail pipe. A rebuild kit was in order, and I was able to get one through an online store. When it finally arrived, I decided it was time to pull off the carb.

 

As I went through the disassembly of the Stromberg AAV, I came across a few hiccups. I decided to tell this story, just in case anyone else is going to face this task (or already has). Probably the worst part of this story is the fulcrum screw that acts as a pivot point; on one side it attaches to the accelerator pump, and the other side, the throttle linkage. Take note! This is a left-hand thread screw! Mine had been cross threaded when last assembled, and thus ruined the threads. There's not a lot of room to tap, or heli-coil.

 

I contacted many different local and online carb places, but no one carried that screw. One shop recommended McMasters-Carr, but they didn't have one either. I wound up needing to find a 76 year old donor carb. It would take a few months of searching before I found one, but it wasn't the same carb. After a good soaking, it came apart better and easier than I thought it would. Though I had the screw, it did me no good due to the thread loss inside the sleeve. I tested the air horn against the gasket, and it fit. The holes lined up. It's a good thing GM used these on most (if not all) of their product lines in that era.

 

Now my carb is a Frankenstein, but at least it's all Buick. I had to cross several parts to make it work. The carb kit contained a new accelerator plunger, but it was far from being within tolerance, and I had to reuse the old one. Also take note: Your kit will NOT come with any information on your Delco-Remy vacuum switch or your choke assembly either.

[carbking]

Would like to add a bit to this post.

 

As the OP mentioned, the fulcrum screw on HIS carburetor IS left-hand thread (the Stromberg part number is P-20611).

 

HOWEVER, THIS IS NOT TRUE FOR ALL STROMBERG CARBS OF THIS TYPE!

 

Several use a right-hand thread screw (part number P-19433).

 

Consulting the factory service literature FOR THE SPECIFIC CARBURETOR BEING WORKED ON will often save the issues caused by some previous owner of the carb prior to the OP's ownership. What generally happens is that the individual working on the carb is not aware of the left/right issue, and just attempts to loosen the screw (over-tightening in the process). As the body is zinc alloy (pot metal, white metal, whatever you wish to call it) and the screw is steel, over-tightening the screw will strip the threads. Once the individual working on the carb figures out (or is told) about the left hand thread, the screw can be withdrawn, and the body threads come out along with the screw. For this reason, we reproduced both left and right years ago.

 

And to the OP, glad your persistance paid off.

 

Jon.

[FLYER15015]

Jon,

Just to jump in here, can you tell us how to identify the LH/RH type of Stromberg ?

Is there a number on the carb somewhere that identifies which version we have ?

In another post a while ago you mentioned that since my '40 LTD lives at 8500 ft. I should consider rejetting (smaller ?) her for

that altitude. The lowest we go is Pueblo, Colo. elevation 6500, and the highest is Leadville @ 10,000. Not a lot of air up here.

I did clean the plugs this spring and they were black with soot, but fortunately not wet.

Are smaller jets available thru you ? Do I need mains and idle too ? Just asking.

Mike in Colorado

[carbking]

Mike,

 

This link will help you identify the carburetor:

 

http://www.thecarburetorshop.com/Carburetor_ID.htm#IDStromberg

 

Once you know the exact identification, then you can consult the factory (either car manufacturer or Stromberg) service literature for that carb. The service literature should give you the part number for the fulcrum screw, which along with the info by part number in my first post, will tell you if left or right hand thread.

 

At 6500 ~ 8500 feet your mains should be approximately 0.002 smaller than standard.

 

Idle can probably be adjusted with the idle mixture control screws.

 

As to your last question, this website is not the place for me to give that answer.

 

Jon.

[FLYER15015]

Thanks Jon, for the link.

Can you PM me with the last question ?

Mike in Colorado

[carbking]

Mike - I don't use PM's. Every forum is different. Arf, Arf Please either email or call.

 

Jon.

[Guest 39Time]

Thanks for adding that Carbking! Just a word of warning on the carb identification however:

 

When going through this process, I discovered that there were markings on the top (air horn) section of the carb. My car originally would have been stamped with a 7 (Buick), followed by a dash and 22A (or 23A). At some point in its life, the carb was changed to a Stromberg AAV26, which bore the marking 7-57 (Buick, 1941-1947 60/70/90). After my frankenstiening, it now is an AAV26 with an AAV16 air horn, which bears the marking 7-66 (1941-1947 Buick 40 Special/50 Super).

 

It definitely makes for a more difficult identification process, but it's a necessary evil in keeping these old gals on the road. In addition, here's a link to help identify some of these carb types:

 

http://www.buicks.net/shop/reference/carburetor_numbers.shtml