Apache running too rich

[chevyfiftynine]

Hi Guys,

Just joined tonight, first message. I have a '58 Apache 6 cyl 235 ci column change, half ton stepside. It has two non-original Rochester carbs. It starts and runs fine, but the plugs are very sooty and the consumption far too high. If I turn down the mixture it won't start. I could believe it was an intake leak allowing too much air in, and therefore needing more fuel, but if it was then getting the correct mixture, the plugs shouldn't be thick with soot. It's driven me nuts for months. Any ideas?

[dwcsr]

Idle mix is not the issue. I would go back a make sure the float levels are correct. Make sure you don't have any loose jets or other parts letting gas leak into the manifold. The carbs may just be to big for the engine. Your getting to much gas. Are they 1 barrel carbs?

[chevyfiftynine]

Thanks for your reply -they're 2 Rochester single barrel carbs. One has RP GM on it, but the bodies are not identical. The intake manifold is Offenhauser. I think you're right - they're probably the wrong carbs for the engine. Can these be modified, or are there other carbs that are more compatible?

[dwcsr]

Rochester "B" carbs is usually whats used. You may find better info over at www.webrodder.com , the guy that runs that site is very good with GM 6 cylinder engines, or http://www.stoveboltengineco.com/ or www.stovebolt.com they deal more with the hotrod 6 cylinders that this site does.

[OrrieG]

inliners.com is another good site. If the carbs are not the same it will be difficult to tune and syncronize them. You might also need up upgrade the cam and exhaust side they all effect each other. Someone in the past just put on the manifold and twin carbs without thinking through the whole process. Same as putting a 780 holley on a stock 350 and wondering why it runs rich too.