Inliners International Forums General Discussion Engines '78-'79 Smogged Monojet Carb?

I've been researching the Rochester 2GC as a potential low buck carb upgrade for my integrated head '78 250cid Chevy, until I can afford a complete top end swap of exhaust, intake, valve cover, and lump head. So I've been reading my Chilton repair manual from the '80s on the carb tuning procedures and noticed that up until '78, they included instructions on idle screw setting in the tune up procedure on Monojets. For '78 and '79 it says that the idle screw adjustment was removed as part of emissions controls, so under my tune up instructions for my '78 it only talks about setting the different idles on the solenoid and linkage.

However, my carb on my '78 has an idle adjustment screw on it? There's no recessed area for it to have been capped over and concealed from access, or any indication that it had been drilled out. It just sticks out with a black plastic end cap that has a pointer on it to indicate how far it has been turned when adjusting. It has no limiters on it to restrict how far it turns, and can be screwed all the way in or completely unscrewed and taken off. The guy I bought the Camaro from owned a lot that he had mechanics on, and said he had one of them rebuild the carb, but didn't say anything about swapping in an older carb?


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Is it possible that although the Quadrajets and 2GCs had their idle screws capped, the Monojet in its last two years on the inline 250 was left the same as it was in '77 or earlier? I really don't know why I can adjust my idle on my '78?

Starting in about 1974 plastic limiter caps were put on idle adjustment screws. We would just break off the little tab and adjust the carb. Starting in the 1979 model year a steel plug was required over the idle mixture screws. Usually to get the plug out part of the carb casting had to be broken away by design. I did it a couple of times, the result was only about the first 1/4 turn out would help then turning the screw more wouldn't make the mixture any richer. You have to drill out th hole to get more fuel. Jay

Ok, that's why I don't have the metal caps because mine is a '78 and the Monojets in '79 had them. But all the reference books seem to think '78s have them, maybe because they were introduced in '78 on '79 models?

Say wait, I need to disassemble the carb to drill out the internal hole for the idle mixture? I thought the drilling was just for the metal cap?