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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 79gmc15 on May 05, 2013, 08:37:38 pm

Title: Vacuum pressure
Post by: 79gmc15 on May 05, 2013, 08:37:38 pm

What kind of pressure should I be expecting from my motor? 1986(?) From a van 305, stock pistons/ heads, comp 268 he cam, sp2p intake, q jet. Idle is set by ear but close to 700 rpm. Timing is set by sound/ping/vacuum gauge. The timing tab and balancer dont match up.

Thanks!

Title: Re: Vacuum pressure
Post by: Fairlane514 on May 06, 2013, 08:01:32 pm

Your timing mark is probably at the 12 O'Clock position on the 305.  Stock should be around 17-19 inches of vacuum. I have about 17 on my stock Goodwrench 350. I'm guessing with that cam probably around 15 inches.