The Stovebolt Site Forums The Shop Area Engine Shop Updating my Zenith carb.... advice please.

I could use some direction and advice on replacing my zenith with a new carb. Sources would be great. I've ended up going in circles on this and would appreciate some solid advice.
1955 GMC 1 Ton 248
Thanks....

Are you sure you need to replace the carb? That zenith is about as good as they come for these engines.

I am having the work done so I'm not hands on in this carb project. My mechanic has had it rebuilt twice but there seems to be a problem with it leaking around the throttle body. It runs pretty good but has a burp in it when you start accelerating. When I stop, it smells like it's flooded and it's hit or miss as to how long it takes to start it again. By the time it runs it's running the battery down. Now, sometimes it starts right up but it seems like the longer you let it sit to a certain point, the harder it is to start. I can go out first thing and it will start right up, summer or winter without choke or touching the gas peddle. You touch the gas, you're flooded. I'm just tired of messing with it and want an engine that starts when you crank it.

With no offense meant to anyone:

That carb, if properly rebuilt and properly adjusted, should be good for a QUARTER of a MILLION miles!

Rebuilt twice and problems???

Maybe the carb is not the issue!

Questions you need to have answers to:

(1) compression test
(2) has an electric fuel pump been installed
(3) has a pertronix conversion been installed
(4) has a complete ignition test (with scope) been done

Check this link: http://www.thecarburetorshop.com/Troubleshooting.htm#Fuelleak

And this one:
http://www.thecarburetorshop.com/Troubleshooting.htm#Hardstarthot

Starting without choke cold or hot (unless you live in Honolulu, San Diego, or Miami, etc.) is a sure sign that either the carb is WAY out of adjustment internally, or the rebuild didn't address the issues, or there is too much fuel pressure.

No carburetor (or efi for that matter) is going to work properly if not properly set up.

Get some answers, and give me a call. No charge for tech advice.

573-392-7378 (9-4 Mon-Tues central time).

Oh, and suggested list price for the new Zenith replacement is right at a thousand bucks. How are you going to feel when you buy one and have exactly the same problems? Of course, you might have a friend in the business. I don't have a current wholesale price list, but in 2006 (my latest wholesale list) the wholesale price was over $500.00. Betcha it hasn't gone down in the last 10 years!

Jon.

I agree, don't give up, your rebuilder has missed something significant, perhaps in the manifold or cylinder head.

You should be able to solve the throttle body leak by installing bushings on the shaft. Wear on the body is normal and the bushing job is pretty straightforward. Having a mechanic older than dirt helps.

Soundbiscuit,

If you're interested in buying a new Zenith carb, you can purchase this brand new straight from Zenith Fuel Systems. It's not cheap, but it will do if you're really looking for a new one. And it comes factory adjusted as well.

This is their new website. It used to be called Autotestsys.com, but all of their items are now on here. The Zenith carb for your 1955 GMC 248 is part number 14275. I have a 1955 2nd Series 248 and this is the exact carb. Their new site does not have all the pictures for their carbs yet. Their old site had the pictures for all of their Zenith carbs.

http://norfar.com/collections/carburetors/products/zenith-14275-carburetor



A.R.

If Jon no longer rebuilds carbs, call Larry Isgro - he backs up his work.

http://www.yelp.com/biz/larry-isgro-carburetors-wantagh

The Zenith 14275 is a great carburetor, and it is the suggested aftermarket REPLACEMENT for the G.M.C. 248. And yes, it DOES come factory adjusted TO ZENITH STANDARD SPECIFICATIONS NOT TO THE SPECIFIC NEEDS OF A 248.

With no offense meant to anyone, the 14275 would be more difficult to adjust to the 248 than the original carb which had been rebuilt twice, which was specifically calibrated for use on the 248.

For the record, we are a distributor for Zenith and stock the 14275 carburetor, so I could have offered it to the OP earlier in this thread. However, I personally dislike selling something that is NOT going to fix the problem just to sell something.

Jon.

Don't change carburetors- - - -change mechanics!
Jerry

Well that makes two for keeping the carburetor and R & R 'ing the mechanic.
Jeffrey