400 Rebuilding question

I am rebuilding my 400 for the first time for my 68 GTO. The cylinders dont require boring out, but should I bore it out? They have just a small ridge that I can take off myself. I can reuse the pistons and just buy new rings.

Should I bore it out and get new pistons? Will it be worth the extra money. Boring and new pistons will cost me an extra $500 at least. What should I do?

yes i would highly recomend that you bore it and not hone it that sml ridge might come back and bit you on the a#@. i would take it .10 over it will cost you like you say around 500.00buck thats better than
buying a new block and rebuilding it. But honnestly i coudnt tell you for sure with out feeling and seeing the ridge..but It would be better to bore it P.S total seal has a very nice set of ring's that will give YOU 100% TOTAL RING SEAL and will make the rings work not you'r pistons and inreturn will give you better torque and longer life and will burn cleaner.there around 150.00 a set but i highly recomend them..Ive started useing them around a year ago and have been so pleased that i wont buy any other ring for a pontiac except total seal they are gapless ring's WOW .....P.S if you have a machine shop that you really trust ask them they will be able to help as well with that but being me and I'am a machinest i would bore it over .10 with 9.5:1 comp, flat top 4 valve releave to bring down comp
to 9.0:1 for pump
gas.. I like seald power and TRW.hope you luck
TravisWilliams@EdWilliamsMachine



travis williams

take your block to your machinist and have them measure the each cylinder.
You may or may not need to bore it ,they can tell how worn they are, remember you are working in 1/1000 th's of an inch so your eyes can't always tell. but if you are tearing it all the way down(to change bearings and such)you should probaly have the clyinders honed. if you are going to all that trouble is it worth putting old pistons back in or spending $250 for new ones(plus balancing). It would suck to spend all that time and money only to have problems with a 30 year old piston and have to start all over. good luck -let us know what you do.

just remember....once the block is bored to its limits , bye bye block... If it already has never been done , like 6t5 gto said , let a good builder make that call after they look at the block.... good luck


Dave

This isnt the original 400 that came in the GTO....It came out of a trans am...