You are 100% correct Marcus. The block was bored almost perfectly for the 2618 alloy piston which is similar clearance specs for all the forged pistons I used back in the day but NOT for the pistons they usek/advertise in the Z460 block .
.006" was the "go to" forged piston clearance #'s back in the day and that happens to be almost exactly what Mahle recommends for the "other" piston that is NOT used in my engine. but in the same block for nitrous and blower engine configurations. Like you said- Ford slapped either the wrong pistons in OR just finish hones the cylinders as a "one size fits all" (unbelievable- almost). I can't believe Ford is still doing this...
If I had the time I would have had Jim build me another block like I had him do for my 418 years ago (I did the specs and assembly). He does great work (Ford Strokers) and I'd reocmmend him to anyone. I didn't have the 6 months wait time for another block from him or I'm sure I wouldn't be stuck in this situation I'm in now. I have been dealing with this for 4 months now.. Sent them another email last night.... Ford doesn't give out phone numbers.
Talked with Mahle again last week and they said the same thing when discussing finish hone clearances as the last time I spoke with them in early October... "there's your piston slap".
Thanks for sharing your info.... makes me feel like I'm not the only guy who experienced this. What are they thinking by not following the piston manufacturers recommendations????
So are you saying your engine builder figured out the finish hone clearance was incorrect and put in custom pistons to make up for the extra .003" that Ford spec's
OR what exactly did they do? thanks
I have two viable options:
1- custom pistons appr. .003" larger dia
2- sleeve all 8 holes in the Ford Racing block and buy new Mahle pistons and finish hone it to the dia Ford SHOULD have done it the first time- just follow the piston manufacturers specifications.