Bottom End Rebuild Time


Mar 10, 2003
I need to rebuild my engine, I've have denation problem under low boost say under 10 psi and my scan master would pick up 4-8 deg's for knock. Well I did a cylinder leak down test today on two cylinders the back one on the right side was fine but the front cylinder was not I could hear air leaking out and on the LH cover air was blowing out where the oil cap would be. I was told it sounds like I need rings. It smokes when I start it and pretty much keeps on smoking. Should I get the block honed or rebored? Where can I get a great set of piston rings for these cars? Can reuse my pistons or do I need to get some new ones? Any advice on what to do and what to get would be great. Thanks, Jason
Well in order to do it right, you will probably need to bore and hone the cylinders and replace the pistons and rings. Stock pistons aren't available in any size (std or oversized) so you will need to find some other pistons to use which is a challenge in itself as nobody carries a piston for a car that they only made 1555 of. TRW/Sealed Power makes a forged piston for the GN that will work but it will increase your compression about 1/4 of a point but cost under $300. You could also get JE or Ross to make "custom" pistons which will run over $600 but will be stronger and lighter than the TRW's. The decision is really up to you and your wallet:D

If you pull it apart and the cylinder wall are still in good shape and you just need new rings, you may be able to rehone it and reuse you pistons with new rings. I have 5 good used stock TTA pistons with 36,062 miles on them so if you need any PM or e-mail me.
ATR catalog has TTA specific TRW forged pistons with rings for $450 if I remember correctly.

Bore it .030 use trw's, it will put you at close to 9to1 you can choose to clean up the chamber(unshrouding) which will increase the volume and lower it a tenth or so. Or you can check with Percy he did have some Ross pistons a while ago. i believe in .020 over. You could also get stock bore trw's clean up the cylinder with a .005 hone and use file fit rings .005 larger to offset and shouldn't have a prob. Could even use your stock tta slugs, but as long as it's open throw in the forged it's ins. imho.
Thanks, Guy's for the replies. I called John Pearcy and got the .020 Ross Pistons, Just hope the block hasn't already been bored out.
I believe all pistons are stamped if they are oversized, that should tell you immediately if the block has been bored.