discostu

I know this is not a ls. However it's still cool. 69 with dz302 4053 holley. 72 primary 76 secondary. Vacuum reads 12. Power valve 6.5. Idle is 900 rpm. So problem is runs like crap. I can turn idle mixture screws all the way in and it doesn't affect motor at all. I've check float level. And used vacuum on the power valves to make sure they close they close at 5 psi I didn't see the psi drop while holding it there. Anything else I can do? Need help don't know what else to look for.

ZONES89RS

iTrader: (25)

Kfxguy

iTrader: (1)

1) whats your vacuum at idle? the vacuum needs to be higher than the power valve
2) big cam? how much do you have the throttle blades cracked? are you past the tranfer port holes? i'd guess thats your issue

this may help if you havent read it.....

https://www.holley.com/blog/post/hol..._valve_tuning/

discostu

The vacuum at idle is 12.
stock 302 cam believe it was a 30-30

Pop N Wood

iTrader: (1)

Turn the carb upside down and measure the transfer slot showing, both primary and secondary. Should be right at 20 thousands of an inch. Any more and you are off the idle circuits and the idle screw is ineffective. This link has a picture

https://www.onallcylinders.com/2013/...y-carburetors/

Blown power valve could cause it as well. As could a leaking gasket or blocked air bleed.

Doug G

Agreed....too much transfer slot (butterfly too far open)

discostu

Thank you for the help. It was the secondary being open to far. After a few turn off the adjustment screw it works as it should.

G Atsma

Glad you got it fixed! And thanks for reporting back, as it will help others.