Im rebuilding my LTI that I use in road racing. My machinist says it only needs 10 over but recs 30 over due to availability of pistons. I would like to keep it to 10 if possible because I will likely need to rebuild this motor in the future and would like to lkeep as much metal as possible. Called summit and they could only find 20 over. Anyone know where I could get 10 over pistons that would keep the stock CR of about 10.4 with everything else the same as stock?

 

he recommended 30 over because they are an off the shelf part. a 10 over piston will most likely have to be special ordered or a custom order piston and will cost a lot more. If a future rebuild is your only obstacle then go with a 30 over piston and in the future just pick up another block for $150-$200. That will be still be cheaper than the custom piston.

BTW, you can just call any of the major piston manufactures and they can make you what ever you want, and can most likely give you a price right over the phone.

 

you can SAFELY bore that motor .060 over, and pistons are commonly available from .030, .040, .050, and in .060, i dont see where going .030 would hurt a thing bro, honestly it would give you a solid fresh start and you could still rebuild the motor later with no probs

 

I went with a .010 over piston on my 396, and it was custom ordered from J&E. I think for the extra $150 bucks or so for the custom was worth it. I just didn’t see why, or the need to go .030 over when my block cleaned up fine at .010. I wanted to keep the cylinder walls thick for future builds/rebuilds, and not to mention that these blocks are no longer manufactured, haven’t been in about 10 years now. It’s something to keep in mind. World? Dart? GMPP? Are you guys reading this?



Nick

 

NO DON'T JUST TRY AND BORE A LT BLOCK .060" over without a sonic checker!!!!!! BAD IDEA.

There are some shelf pistons that are .020" over so if you want to start small there ya go. I like Mahle pistons and they start at .030" for a SBC/LT1 and even then you can't always get the bores where they need to be with just a .030" piston.

Bret

 

Thanks, I just called them and told them to go 30. I had no idea finding pistons would be so hard. I thought I could just call up summit and say "everything is stock, I need .030 over pistons. Not even their tech line has a catalogue or list of pistons for simple refreshes like this. So I have the CR calculator out and Im going over every piston with the right bore and stoke and calculating CR with each one to find a CR I like. I realize it all can change depending on how much you might need planed off the head but for everything stock, shouldnt you be able to look up a "replacement" .030 over piston?. THEN when you consider the LT1 comes with flat tops with 4 valve reliefs I want to know this- Will my valves clear ANY aftermarket piston with 4 valve reliefs? And if I have to go to a dished piston to get the CR I want can I just "assume" the dish is as deep as the valve reliefs of the stock pistons?? This info isnt listed on web sites (depths of dishes and reliefs) so how am I supposed to know? Actually I am waiting for the machine shop to tell me how much if any they have to plane off my heads, then Im going to pick some piston and give the info to Bret (my cam is his custom grind) and get some advice. Who knew this stuff was so hard??

 

 

That's what I thought, but hey, close enough.

 

Half the racing season is already over, I need to get the pistons for balancing to the machine shop buy next week or it will delay my build for another 2 weeks at least, I know nothing about ordering custom pistons nor do most on this board, nor did anyone above bother to offer any info on who to call etc. .030 pistons are the most widely available and the easiest to find, thus it appears off the shelf is my only option at present. We all have reasons for the decisions we make. I appreciate the input, but you can keep the attitude.