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Discussion Starter · #1 ·
So I recently got my car back together and running. I rebuilt it because it didn't run right and after a compression check found out the rings were worn out. So fast forward I decided to do a on3 turbo kit and switch out cams and valve springs. Now compression check comes back at 150 per cylinder and leak down is around 20%. I am at a loss, the car is running a super sniper and runs ok, besides over heating now after driving awhile. Looking at my combo can anyone see anything that would cause a low vacuum at idle? I've also checked for vacuum leaks numerous times just to be sure and have found nothing. I'm just at a loss of where to go from here or what to check.

Cam - .634/.601 @50 258/278 114 lobe seperation
Valve Springs - 987 Comp Cams, Harland Sharp 1.7 RR and Trick Flow 7.7 pushrods
Vic Jr Heads & Intake
Holley Super Sniper 1250
on3 turbo kit
 

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what is manifold pressure and idle speed?
 
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Discussion Starter · #3 ·
what is manifold pressure and idle speed?
Manifold pressure is about 1-2" at a 1150 idle speed. If i got to around 1,800 i can get around 5 but i wouldn't think that cam would need to idle at 1,800 RPM to gain any sort of vacuum. Timing is at 23 degrees but I've tried anything from 11-28 degrees with no change.
 

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so

intake valves open
air is getting past throttle blade
exhaust is plugged

you say leak down is 20%? that is not good

try a smoke test....

what is the cam expected to make, manifold pressure wise?
 

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Discussion Starter · #5 ·
so

intake valves open
air is getting past throttle blade
exhaust is plugged

you say leak down is 20%? that is not good

try a smoke test....

what is the cam expected to make, manifold pressure wise?
Indy, i had a similar size cam to this before and made 16" so I'd say maybe 10-12". I will try the smoke test next. I didn't think of that, I was wondering if the springs were maybe keeping the valves open slightly.
 

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Did you degree cam? Cam timing off or ignition timing.
 

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Also, make sure the valves aren't adjusted too tight.
 
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Indy, i had a similar size cam to this before and made 16" so I'd say maybe 10-12". I will try the smoke test next. I didn't think of that, I was wondering if the springs were maybe keeping the valves open slightly.

perform a relative compression test by sound

crank without it starting, listen for consistent crank, without a speed up
 
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