No more high compression street builds for me

[Paul_G]

I’m at 195 psi, and on the edge of detonation with 93 octane

I plan to run the same cam that was in the 505, now with lower compression pistons. The problem still leads me to think I got a tank of 87 octane out of the 91 pump. I wish there was a way to test the octane level of the fuel in the tank now.

 

[Dodge Bros]

Trick Flow Power Port 240 aluminum heads. I dont know the quench? I did record compression numbers when it was running good. They were in 210 to 215 range.

210 to 215 is a 93 octane range in a 505. Judging by those compression numbers and the .050” cams specs I am going to guess that is a custom XFI HR cam. If that is correct, those cams are very aggressive off the seat and pump a lot of compression for there size. The 240 heads have very efficient ports, if you keep with that cam (and I am correct on which cam it is) in a 505, the compression needs to be dropped to 9.4 to 9.6 for 91. The TF240s are very efficient ports, with that cam, I doubt you will even miss the compression with your 505.

A different cam would fix it to and leave the compression alone. But it sound like that cam isn’t a bad fit, the compression is just high for the desired fuel.