Intake vacuum reading...????
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Intake vacuum reading...????
On my '81 with a mild rebuild of the engine I am measuring between 11 and 12 in Hg at idle (700rpm) this is with a Comp Cams 268H cam with 1.6 ratio roller tip rockers.
Increasing the rpm to 1500 or so and vacuum increases to about 18-20 in Hg.
Is this about correct?
Still have the computer working, EGR and AIR pump disconnected, stock exhaust.
Thanks for any insight here.
LannyL81
Increasing the rpm to 1500 or so and vacuum increases to about 18-20 in Hg.
Is this about correct?
Still have the computer working, EGR and AIR pump disconnected, stock exhaust.
Thanks for any insight here.
LannyL81
Racer
Joined: Nov 2004
Posts: 485
Likes: 1
From: Oakville ON
Originally Posted by LannyL81
On my '81 with a mild rebuild of the engine I am measuring between 11 and 12 in Hg at idle (700rpm) this is with a Comp Cams 268H cam with 1.6 ratio roller tip rockers.
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Originally Posted by bobs77vet
that sounds ok how does it run? its defintely not in the " oh crap territory"
It just does not run GREAT like I think it should. I was expecting more performance with this rebuild. Still checking everything out, which is why I put the vacuum gauge on it...want it to see if I had a vacuum leak. And it seems that I might have a small one yet as the reading I got is a bit low compared to the response above.
I have checked the intake bolts, carb bolts...all are tight.....should I try the carb cleaner spray around the intake to heads joint for a leak?
Thanks,
LannyL81
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Le Mans Master
Joined: Oct 2005
Posts: 9,429
Likes: 44
From: Macon, GA
Low vacuum readings at idle can also be caused by poor carburetor adjustment. If i'm not mistaken, your car has the electronically controlled "feedback" carburetor--known officially as the Computer Command Control (C3). Not sure how to do any adjustments on these guys. How does your choke work?
Burning Brakes
Joined: Oct 2004
Posts: 763
Likes: 0
From: Loveland Colo
My 350" with XE262 with 114* LSA, 1.52 rockers, 9.75:1 CR & old Q-jet shows 13" at idle and 16" at 2000 RPM. This is on a run stand, without being dialed in exactly, and at 5000+ ft altitude. Figure about an inch loss from spec for each 1000' above sea level.
John
John
