High Cranking Compression
Thread Starter
Heel & Toe
Joined: Jul 2004
Posts: 16
Likes: 0
From: Grand Lake, OK
High Cranking Compression
Been trying to find the source of a vibration in my recently built 355 with a "balanced" lower end.
Did a compression test and had 215-218 in all holes. I have flatops with 4 valve reliefs (-7cc) .017 in the hole. Fast burn heads (62cc) and .028 4.060 GMPP headgaskets. I'm runnning a Comp Cams XR270HR that has intake closing at 61 degrees at .050.
I pulled the timing cover off after finding the high readings and verified that I have the timing set in the 0 degree advanced setting and I "think" I degreed it when I initiall put it together although it's been awhile.
Before I put the high torque starter on I did mess up lots of sun gear teeth but I don't think that would cause a vibration.
The car really runs good on the lower end but I can't bring myself to take it over 4k with the bad vibes.
Does anyone else think the Cranking compression is too high? Any ideas about a cam being advanced too far possibly causing an engine vibration?
I sure hate to take it apart for rebalancing!
Thanks
Did a compression test and had 215-218 in all holes. I have flatops with 4 valve reliefs (-7cc) .017 in the hole. Fast burn heads (62cc) and .028 4.060 GMPP headgaskets. I'm runnning a Comp Cams XR270HR that has intake closing at 61 degrees at .050.
I pulled the timing cover off after finding the high readings and verified that I have the timing set in the 0 degree advanced setting and I "think" I degreed it when I initiall put it together although it's been awhile.
Before I put the high torque starter on I did mess up lots of sun gear teeth but I don't think that would cause a vibration.
The car really runs good on the lower end but I can't bring myself to take it over 4k with the bad vibes.
Does anyone else think the Cranking compression is too high? Any ideas about a cam being advanced too far possibly causing an engine vibration?
I sure hate to take it apart for rebalancing!
Thanks
