The Stovebolt Site Forums The Shop Area Engine Shop Carter YF rebuild questions - Model 788S

I don't even remember where I got this carb. but decided to rebuild it and have run into a couple of issues.
In the attached photo the #1 issue is that there was only a needle that I saw that came out of the hole circled. If there was anything else i didn't see it. There were two ball that came with the kit. A larger one which forces the needle above the rim of the body and a smaller one forces the needle even with the top of the rim leaving no room for a retainer. Maybe there isn't supposed to be a ball in there ?? I haven't even yet seen where those two balls go.
One other thing that threw me off is that a few of the kit parts are of a different design from what looks to be original parts. But I eventually figured those out.

Carb. Model is a YF 788S. 1950-52

I'm sure there will be more questions to come.

I'm interested in any comments as I will taking my carburetor apart next week. I want to watch some YouTube videos and visit Mike's Carburetors Parts website for more info.

Hi Utah and Mikey.

Here is a thread with various pictures of my Carter YF rebuild and questions and answers along the way. Pages 1-5 are discussions about my carburetor's symptoms, discovery that it was a Frankencarter, etc. From page 6 on is the actual core I bought from carbking and my subsequent rebuild of it.

Rebuilding the carburetor was actually the most satisfying and fun task that I completed on Ol' Roy.

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1442479/6

Mike's carburetor isn't always correct nor accurate. My opinion is it should be used for general suggestions. Folks here (including me) have posted many times about the Carter YF models. Do you know which model number you have? The answers to your questions are yes...there should be a little needle in hole 1 and there should be 2 springs above the diaphragm lifter link rod on top and one below. Yes, it isn't easy to get it back together...compressing those 2 springs requires a little concentration. Somewhere around here there was supposed to be a report (I and Jon H wrote it) on rebuilding the Carter YF models. I don't know where it went, though.

One thing I do notice is your carburetor doesn't have the anti-slosh seal. If it was designed for one, it ought to be there. It won't affect the performance, however it will let gas slosh up and run down the lifter link. If you can show us an image of your carburetor air horn (top part) inside, we can tell you if it should have the seal. (you can see what it looks like below).

I have most or all (I can't remember) of the spec/rebuild sheets for Carter YFs produced as replacements for 1962 and older Chevrolet sixes. I also have 4 big Carter books with other makes, but I haven't cataloged what I have in those. If you can provide the model number of your carb (should be stamped on that vertical spine on the outside of the venturi), I can share with you a scan of the spec sheet if it's Chevrolet, and hunt for a sheet in my books if it's for a different make, and share that if I have it. The spec sheets have part numbers for a lot of the internal bits, so you can see if you have, for example, a 964S carb with parts swapped from a 2100S carb.

My Carter YF is a model 788S. 1950-52

The kit I have has this little rubber plug (about 1/4" dia.). Any idea where it goes?

P.S. I got the springs at the top of the pump doubled up.

Offhand I don't recognize it. Where did you get that kit?

I’ve never been inside a 788s, but I sure can’t imagine where that part would fit….based on the Chevy YF’s I’ve seen.

Pretty common for rebuild kits to include a lot of extra things. Could be that belongs in a Jeep or Ford YF somewhere.

The circled plug in the photo below appears to be lead or some other soft metal and I believe it is recommended to be removed in one of the rebuild instruction steps. That is probably where the rubber plug would go. It's about the right size and it's the "idle port rivet plug" mention in step 13 on page 8 of "Mike's Carburetor Parts" manual for the Carter YF.

Is this a Rochester BC carb. and would it work on my '56 3100 235 C.I.D.? It came off my '55 chevy convertible 6 cyl. when I converted it to a 265 V8.

Mickey, DO NOT REMOVE THAT PLUG.

Go back to the link I posted to the thread on my Carter YF rebuild. I asked the same question.

That Rochester would probably work, but the Carter is better, or will be when it's sorted out.

PM me your email and I'll send you this sheet for your 788S. The PDF is too big to attach here, and my personal computer doesn't have editing capabilities in Adobe to reduce the file size... and I'm too lazy to dig my work laptop out right now and transfer it and all that...

Jon G, thanks for your feedback. The hole I'm pointing to in the picture had nothing in it. Mike's Parts show a ball, a weight and a retainer for that hole. I did get the two springs on the pump but there was no splash shield on it.

Otto, I had decided to not remove that plug but it does appear correct for that application. I can't find anywhere it would fit.

Can't remember who ask where I got the kit but it was purchased at a local auto parts store.

Yes, my kit came with a plug as well but the hole is a manufacturing access hole.

Thanks Otto, good to know. I was wondering why they would plug a hole that needed cleaning. It also seemed strange why they would put a rubber plug so close to the exhaust manifold heat.

Yes Mickey, it's a Model BC.

Carter seemed to "waffle" on the type of accelerator pump discharge valve to be used.

The early carburetors, mostly, started with a small ball with a small square weight on top of the ball.

A few of the early carburetors and all after maybe 1958 came with a square pointed needle that was the same mass as the combined mass of the ball and square weight.

A few of the carbs that started with the square needle were switched to the ball and weight, and then eventually switched back to the square needle.

I would use the square needle. This is what comes in most kits.

Jon