I came across a nice, late 70's Q-Jet core (late style APT) that's prime material for a rebuild, the only problem is that it's missing the black plastic cup that fills the void where the early style APT system was (in earlier models). Make sense? Anyway, I was wondering how vital this is to proper operation and if anyone knows where I could get one?

Thanks!

On an early carb you mean the cap that goes in the front of the baseplate? I'm not sure if the cap is necessary to prevent a vacuum leak or if it's just there to prevent the average guy from messing with the factory setting. It certainly won't leak fuel, if that's your concern.

I think he means the little round cup found in inside some models right beside the float and oppositethe accelerator pump. To be honest I never putthem in although I've found a few. I'm not sure what it did, but it isn't much, and I doubt its "missing" since most of the good Rochs I've opened never had them at all.

I think he means the little round cup found in inside some models right beside the float and oppositethe accelerator pump. To be honest I never putthem in although I've found a few. I'm not sure what it did, but it isn't much, and I doubt its "missing" since most of the good Rochs I've opened never had them at all.

That's what I meant, and that's what I figured. Thanks Tom!

Put it back in if you've got it. Fuel can slosh in and out of that space and give you an unstable float level in the rest of the bowl under some conditions. Probably nothing that you'd notice most of the time but the factory wouldn't have spent money to put it in there if it didn't do anything.

Do they always have them, Damon? I have taken apart many without them. Many with them but some carbs they just aren't there. Previous rebuilds perhaps???

Yeah, probably previous rebuilds.