You guys have helped me out time and again and could use you expertise again. I have been trying to diagnose and fix a leaning out problem without any luck and decided to pull my heads to see what is going on. I have a 289 bored 0.030 with 351W heads that are stamped C90E G(?) as near as I can tell. I can't find anything with a G ending and I'm assuming must actually be a B or D with 60.4cc chamber volume. The valves are Ford stamped and believe them to be stock. The pistons are dome topped TRW L2249 N 030. When I bought the car in '06, I had the engine rebuilt and was told the block and headed were decked 0.010". I was told that the compression ratio was 10.5:1 but similar set ups seem to be closer to 11.5-12:1 from what I'm reading.
Since the car is a street car that needs to run on 93 octane pump gas, I need to lower the compression. Here is where I need help.
1) What is the highest compression that I can have to run pump gas?
2) Is there a way to bring the compression down using the current pistons? Different heads with larger combustion chambers, head gasket shims, machining domes down? Or am I best to replace pistons with flat tops?
I appreciate any advise, bearing in mind a limited budget.
Since the car is a street car that needs to run on 93 octane pump gas, I need to lower the compression. Here is where I need help.
1) What is the highest compression that I can have to run pump gas?
2) Is there a way to bring the compression down using the current pistons? Different heads with larger combustion chambers, head gasket shims, machining domes down? Or am I best to replace pistons with flat tops?
I appreciate any advise, bearing in mind a limited budget.