I have 351 clevo with flat tops and closed chamber 302 c heads they have been port matched 4v inlet and exhaust vales can somebody tell me what comp ratio it would have and what other headwork does it need to stop pinging i run it on 98 octane and it seems like it has to much comp i no the open chambers had around 72cc to 76cc and 9:1 .Do they need porting and open the chambers up a bit the 302c had around 58cc to 60cc .
Try timing the spark by ear. Retard spark till pinging goes away, (under acceleration). Timing marks on Clevos arn't always correct, mine are out.
Don't time it be ear!!! Thats just bodgy and can end in teara if you combo aint right, and if the clevo timng marks are out, FIX IT.
You have initial timing to deal with as well as total timing and if someone thinks they can guess these two evens by ear, they won't be near my high powered Cleveland.
10.70 @ 125.00 on the black fun top
408 Cube Cleveland.