Mustang_Geezer
Well-known member




This happened at our last race 3 or 4 weeks ago....
The car ran a slow 15.58 @ 86.89 mph and it didnt feel right at all. Next (and last) pass was a 15.90 @ 83 mph and it lost a cylinder on the top end.
Parked it because I've been busy adding on a 2nd story "mans room" on the back of my shop, so a couple weeks ago I did a COLD compression test and it was 130-135 psi except #4 which was only 50 psi.
Pulled it apart today and this is what I found....

Number 4 piston is junk but the cylinder bores appear to be allright visually. I was at the machine shop today and they said to bring the block in and they can check it out to see if it can be machine honed and then just replace the number 4 piston and rering the rest.
If not we will decide if I want to bore it .080 over or resleeve number 4 or pitch it in the trash and start over with another block.
All the rings are on the top of the piston and the piston land on number 4 is warped.
Number 1 is the only piston that has intact rings.
I thought I was over rpm'ing it with cast pistons being I shift it @ 6400 rpms when I race but they (the machine shop) said it looked like detonation to them so thats what I'm going with.
Engine is getting pulled next weekend and we'll see what happens!


Later,
Doug