I have a 1986 IROC Z that came with a 305 HO. I don't know a thing about carbs as far as tuning or anything beyond the very obvious basics. So I would appreciate any answers. I don't know what the numbers are on it. But I'm curious as to how to lean it out. I scrapped the 305 and put in a 355 with comp cams muthr thumpr cam, flat top pistons, high flow oil pump and a few other things, but I am still using the stock 305 carbuerator. I also am willing to learn more about carbs so don't hesitate to go into great detail, while keeping it simple for a beginner.

Thanks much!
Brandon

 

Computer controlled QJets and big lumpy cams don't play nice together. Which cam exactly did you install?

And remember, that any cam with significant overlap (like the Thumpr series with tight LSA specs) is going to smell a lot more at idle than a stock cam. The high overlap allows unburnt mixture to find it's way straight out the exhaust, even if it's tuned right.

 

I honestly don't know what exact cam i got. I thought the thumpr series was only the thumpr muthr thumpr n big muthr thumpr. But I shouldn't be running on 7 cylinders wyen I start up, until I hold the rpms up to clean it out.

 

If it really is only running on 7 at idle, which cylinder isn't firing should be evident on the spark plug.