Holley model 4160, series 3310 carbs

[dcdoug]

OK, so I must have been hallucinating when I told you I had a secondary metering block. I don't, mine is a standard 3310-11. Maybe too many gas fumes.

I hooked up the vacuum gauge this PM and played with the idle mixture a bit. Leaned it out a touch (1/8 turn on both screws). Vacuum gauge bounces a bit as I have some roll to my idle. Should I turn up the idle to reduce the roll while adjusting the idle mixture so it is easier to see the gauge change?

Also, when I went to hook up the gauge, I noticed that the rubber cover to that front vacuum fitting was missing. I will get a replacement, but am curious as to what effect that missing cover has had? Car runs great, other than sometimes dieseling a bit when I shut it off, which is what I am trying to solve.

[patrickt]

Originally Posted by dcdoug

Also, when I went to hook up the gauge, I noticed that the rubber cover to that front vacuum fitting was missing. I will get a replacement, but am curious as to what effect that missing cover has had? Car runs great, other than sometimes dieseling a bit when I shut it off, which is what I am trying to solve.

You mean the rubber cover where you hook the vacuum gauge and that I said was really easy to drop and lose? If you don't have the rubber cover on it you have a pretty decent manifold vacuum leak. Your car will run rough -- you absolutely, positively have to have a cap on it. A leak like that can really make a difference.

Originally Posted by dcdoug

OK, so I must have been hallucinating when I told you I had a secondary metering block. I don't, mine is a standard 3310-11. Maybe too many gas fumes.

Yeah, I thought so.

Originally Posted by dcdoug

Should I turn up the idle to reduce the roll while adjusting the idle mixture so it is easier to see the gauge change?

Well, you can, so long as you re-adjust your idle back down to a good number after you have your mixture right. The theory being that the very best idle mixture will give you the highest vacuum because the engine is running the most efficiently. You can monkey around with it, and if it doesn't improve, monkey with it some more. You can't really hurt anything.