Holley carb idle issue

[Sonny]

I have a practically new (6 months old) Holley 570 on my 1970 Belvedere 318. I installed a new air gap intake over the weekend and I'm having idle issues when the car is sitting and in drive. It idles fine in park. I've had to raise the idle setting a lot and both mixture screws are out at least 6-8 turns just to keep it running! Before the intake swap it wanted 4-6 turns. I was having surge issues in cruise mode too so I disconnected the vac advance and that issue went away, but the idle issue seems to be getting worse the more I drive it. It has very old points. Could this cause it to want more fuel? I spent 2 hours at a garage this morning and it passed the vacuum leak smoke test. Any advice? The "new" pcv tube is also making loud sucking noises. Take a look at the pics below and see if you see anything suspicious.
thanks!

 

[747mopar]

You stating that it appeared after a manifold swap definitely points towards a vacuum leak, likely on the engine side. Vacuum leaks basically lean your mixture making it want more fuel but also causes tuning problem since your loosing vacuum before the carb weakening the signal. Did you also leak test the carb base? Looks like that manifold has a wide gasket surface that could be interfering with something on the carb not allowing it to seal?

 

[747mopar]

Also double check that you have all unused ports plugged in the carb and intake..... you would have likely found that in your leak test but who knows.

 

[65-440]

6-8 turns, that's crazy ! Def check for vacuum leak

 

[HEMI-ITIS]

Did you say POINTS???????????,,,,,,,,
Start with a vacume gauge and go from there.

 

[dryheat]

"loud sucking noises" from your PVC hose? If it plugged into the back of the carb ... take the hose off and plug the carb it to see it the issue goes away.

 

[RJRENTON]

It possible that the carbs primary power valve has failed, causing a huge internal vacuum leak. Another possibility is the carbs base plate gasket has failed or the carbs base had broken due to incorrect tightening, causing a vacuum leak as well. If the manifold to cylinder head gasket has failed, there would be a blue haze from the exhaust ftom the oil being sucked in from the lifter Valley...although this is a somewhat remote possibility.
Let us know what you find
Bob Renton

 

[Sonny]

I gave up and took it to a hot rod shop. Will let you know what they find $$$$$. Ugh.

 

[HEMI-ITIS]

Sonny,Sonny,Sonny,,,,,,,,,,,,,,,,,,,,,,

 

[Bill Monk]

My bet is a vacuum leak at the manifold somewhere. If you can't find it anywhere, you can spray some carb cleaner around (watch painted surfaces) and when you find it, the engine will smooth out.

 

[Tempest 455]

Is it a Holley Avenger?

 

[Sonny]

Is it a Holley Avenger?

No. It's a new Holley 570.

 

[Sonny]

It's looking like l had a vacuum leak at 2 runners after all. I used edelbrock gaskets, but they felt thin and we not embossed at the openings. I should have trusted my gut and bought a thicker set. Live and learn.

 

[Sonny]

It's looking like l had a vacuum leak at 2 runners after all. I used edelbrock gaskets, but they felt thin and we not embossed at the openings. I should have trusted my gut and bought a thicker set. Live and learn.

So it wasn't just me , the shop had to install it twice too. Turns out they had to machine the port face to get it to seal. I feel a little less of a failure!

I am loving the new 440 leaf springs that they installed however!