“……Well poo.......idle screws still have to be 4.5 turns out approx to idle without my hand over the carb.......still has a flat/dead spot off of idle……”


Bummer. It’s unfortunate you don’t have a carb number, but if you don’t you don’t.

First question I have is do you have an operational choke? The reason I ask is that it appears ion one picture that the fast idle cam linkage is missing. Are you bringing the engine up to full operating temperature before adjusting the idle and is that flat spot still there after it warms up? Some engines like a fair amount of choke until they warm up.

I’ve come across the bases with the holes a couple of times, it shouldn’t make a big difference. Like 34_40 I think I would probably plug them too but mainly just because I don’t like unfiltered air either.

That being said, the first thing I would check would be the carb base to intake gasket. Over the years I have come across many base gaskets that don’t effectively seal the carb to the manifold. I just ran into this on the two outboard carbs I rebuilt for the Tri-Power, the gaskets in the kits did not completely seal the front of the carb. Because I’ve run into this before I always turn the carb upside down and lay the gasket on the base to verify the proper fit. The gasket I usually use if I need one is a Car Quest G7327 (it’s an old number but hopefully it will interchange).

Although I’ve only seen the problem a couple of times another thing I would check is the PVC valve. The good one are calibrated differently. If someone threw a valve designed for say a 454 onto you engine with the smaller displacement there is a real possibility that you are pulling too much vacuum thru the valve.

While 4+ turns on the idle screws does sound a little excessive I’m not sure I’d be overly concerned about …….provided that is where they want to be after the engine is warmed up. If you turning them out to keep it running when it’s cold…..it could go back to my comments about needing the choke.

The flat spot could be a couple of things. If it happens when you mash the gas pedal it sounds like the accelerator pump shot ……verify you have a good squirt that starts as soon as the throttle starts opening. If the shot starts late you may need to drop the accelerator pump a bit which can be accomplished the straightening the external pump linkage just a bit.

If the flat spot is just off idle with a slight pedal opening, you might try backing out the idle screws just a bit more and/or adding a couple me degrees advance to the timing.

As far as the vacuum port on the front of the carb, it depends on the carburator I’ve seen them both ported and manifold in that location. Easiest way to check is pull the line and put your finger over the port. If you feel vacuum at idle it’s manifold if you don’t feel any vacuum until it reved up it’s a ported vacuum port…….the later 2Gs actually had two nipples in that location one manifold and the other ported.

Hope this helps.

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