I'm wondering which head would be best for my car. I have a 1973 240z that I bought last year, that was supposed to have an early Rebello engine. Unfortunately there is no documentation on it and Rebello doesn't keep records for early 1990 builds. 2 months ago the head went bad with a burnt valve. I replaced the E88 head with a P90a that had been rebuilt, just to drive the car, and took the E88 to a machine shop to get it rebuilt. I now have the head and realize that its a standard head with no porting, or polishing. The shop replaced the springs, did a 3 way valve job, lightly shaved the head to eliminate some very minor unevenness.
The question is should I re install it or leave the p90 on? I have someone who may buy the car but wanted the E88 back on, assuming that it was a built head by Rebello. He now knows that that isn't the case. I have a n L28 block, rebuilt, with flat top pistons that the P90a was on.
Are there any performance gains between the 2 heads assuming everything else are equal..
By the way when changing the heads, I didn't have a micrometer to measure the bore, so used a paper to get the bore size and than miked it at work. It measured at 89mm.