1973dusterkid
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What would cause the idle to be slow droping back down to base idle.Info in signiture.
Carb tuning. Centrifugal advance weights in the dist. either sticking or the springs are a little too light. Vacuum leak. Just to name a few
Does not change with the tuning of the carb as far as the dizzy not sure no vacuum leaks I know of.
I think it may be the valve springs. I am using stock 340 j head springs with this .506 cam.
Valve springs will limit your max RPM's, but is not going to be the idle problem.
Sounds like distributor weights to me.
What RPM's is your idle set at currently?
its a holley 750 electric choke. The vacuum advance is hooked to the carb.
Where is it hooked up to the carb? The baseplate or off the passengers side of the front metering block?
Try just unhooking the vac advance temporarily and see if it quits doin it.
Easy information could come from this.
Passanger side block
If I unhook the advance the idle rises.
Ok, that's the correct place
If the idle rises when you unhook it that means it's pulling vacuum there and the reason the idle rises is you've created a vacuum leak by unhooking the hose. It also means you have the primary idle speed set so high it's exposing that port to vacuum which should not be. That port should never have vacuum at idle. I'd back off the primary idle speed screw and adjust the secondary idle speed screw in 1/2~5/8 turn. It's the one located on the bottom side of the base plate on the pass side and you have to access it with a small screwdriver. You may have to take the carb off to get to it because some manifolds cover it up when the carb is bolted down. If you do that and find it helps but it still needs more you may have to drill some small holes in the butterflies to let more air in at idle so you can lower the front idle speed more to get it in the proper relation to the idle feeds slots.
Ok I will check and do that. Its raining so I can't really do much.
Well its raining and a 7 degree low monday
Plugged the line the idle did not accelerate, But the idle is still slow to decrease.