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Discussion Starter · #1 ·
If I put a test gauge on the intake how much vac. should I get?
I have 8.5-10 on the gauge. it is not steady. it goes up and down with the cam lope but, it also goes up and down seperate from the lope. if I pinch off the PCV valve hose. it smooths out a bit.
I am trying to see if I have a vac. leak. I am getting popping back into the intake
 

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Discussion Starter · #2 ·
Anyone?
 

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My cam pulls between 8-10". It's a custom grind from CamMotion...574/591 lift and 236/247 duration. Idles some where around 1000-1100.

Chad
 

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My Stage1 cam pulls 12" at 900rpm idle....it pulls 10" at an 800rpm idle.
Do the idle reset procedure and maybe clock your meter. Also keep TPS below .96 volts. Spray carb cleaner around vacuum lines...if idle shoots up you've found a leak
 

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I get 15-17" at idle (950rpm), but my cam has a 114 LSA which helps.
 

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I was getting about 12.5" of vacuum with my F-Cam. This may sound like a stupid question, but if you just put the engine in... and you're popping up through the intake... could your valves be hanging open a little? I've heard of this before. I would imagine that this would also have an effect on your vacuum. Everyone has a recommendation, but I'd suggest a half-turn past zero lash, lock your rocker nuts, and torque them down to 24 ft-lbs. You will probably see about another 1/8 to 1/4 turn during the torque process.

I had a vacuum leak in the past and also had low vacuum, but the needle on the vacuum guage was pretty steady. Maybe this is something else. Just trying to help.
 

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Discussion Starter · #9 ·
thanks for the replys. I will try to see why my vac. is so low.
I did the carb cleaner thing and found nothing. then I turned on the garden hose to it and it did not do anything.
So I am not sure what is up here. I just did my valves there all at 1/2 turn past 0 lash.
Let me explain as best as I can what it doing. When driving the car at any speed it will run ok until I let off of the throttleand let it coast down 300-800 rpms then when I give it throttle again it popps and sputters and stuff until I get it up out of it. kind of like it needs to clear out or something then it clears up and runs ok til I let off of the gas and it starts all over. It only does this above about 1200 rpm's any lower and it most of the time will run ok.
I just reset the idle how ford says to do it. which is different than I was doing it. the SOB won't idle now but oh well i'll fix it tomarrow. I had the FP at 42# and put it to 40# and it pulls harder but pops worse. SO, I think I am getting lean somehow.
What would cause this?
 
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