02-07-2017, 12:49 PM
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CC Member
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Join Date: Feb 2012
Location: Keller,
TX
Cobra Make, Engine: Lonestar Classics LS427. Self-built 408W, AFR 195 heads, Performer RPM Intake, Quick Fuel 750, 407rwhp, 479rwtq
Posts: 549
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Not Ranked
High initial timing
I got the motor put back together after the heads were rebuilt. Started right up. While the heads we off I verified the cam timing and crank timing pointer were accurate. Went to set the timing... Using the vacuum gauge I turned the distributor until I got best vacuum. RPM around 1000. Locked down the distributor them checked it with a timing light and it was at 55* BTDC!
Best vacuum was 16.5 inHg. If I drop the timing down to 15* or so, vacuum falls to 14 and it runs rougher. AFR around 14. Vacuum disconnected and plugged.
Any ideas what's happening? If it was a tooth off, i would just rotate it back and it would run better at ~15*. I have an old cap with a hole that i can verify the rotor is phased correctly. I just ran out of time today. Thinking thru possible fixes.
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