View Single Post
Old 09-07-2016, 07:34 PM   #26
davepl
Registered User
 
davepl's Avatar
 
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
Re: Idle vacuum - why only 10 inches?

I talked to him about it today, and he said:

- It's unlikely it'd run as well as it did/does with the cam off by a full tooth
- Near impossible with a brand new double-roller that it'd jump

So, if it's off, it was installed wrong. And if it were installed wrong, it'd be a lot worse off than it is. Or so the theory goes.

While the responsive-down-low does sound like it, if the cam were advanced, though, I'd expect strong idle vacuum. If it were late, I'd expect it reduced.

I really am not in the mood to pull it apart and degree the cam just to chase a number when there are no other symptoms (but I verified with a new gauge today that it's only got 11").

I also disconnected the vacuum booster and accessories today to rule them out as a leak source, no change.

My cam specs follow - it's more than stock, but not big or wild I wouldn't say:

Intake: 214
Exhaust: 218
Lift: .496
Int Cntr: 110
Ex Cntr: 120
Overlap: 66
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought
1969 Pontiac 2+2 427/390 4-speed Coupe
1969 Pontiac 2+2 427/390 4-speed Convertible
davepl is offline   Reply With Quote