Build updates, bore question

[xpertsoldier]

Hello, I have been a member for some years now and yet I am still a newbie and have no access to anything. I usually find my answers by searching the forums, googling myself amongst asking other folks. I decided that I want to have better access on the forums and that I need to start posting more. Before I forget Happy Holidays to y'all!

I just got my hands on a T67 with a P P trim turbine I have two housings a .70 and a .81. What do you guys think I should start off with? I have a build motor with forged internals however my head is stock. I am looking to get some new springs and cams just waiting for a good deal to pop up. I purchased a top mount exhaust manifold from one of the folks on here selling off the forums. Very excited to get it in. Will most likely wait a bit till I get some new springs for the head.

I am also in the process of building a 90 GSX for my sister. I do have a question about this. I have a old timer helping me, and he called me freaking out yesterday. I purchased manley forged rods and .040 manley pistons for it. The block needed to be bored .040 to get it nice and usuable again from the previous owner. Anyhow the machine shop went and bored it and then told me I needed .040 pistons. Ok, np so I went ordered them and called it a night. The old timer was freaking out regarding the machine shop boring the block without the pistons. He was the one that brought the block to the machine shop and told them to get it ready to be used. So if they machine shop needed the pistons why did they bore it without them? Am I totally screwed now? Or do I need to bring the pistons and block back to the machine shop and have them just install the pistons and rings? The old timer is having one of his buddies doing this part of the build and he is talking about matching the pistons to the cylinders and such. If the pistons are all the same size and the cylinders are all bored equally what would this matter?

I appreciate your insight and enlightenment. This is an unchartered area for me.

Thanks again and Happy Holidays!

 

[hotrodssnova]

Usually the machine shop bores the cylinder, and finish hones the final clearances. Time to measure the pistons and bores to make sure you have proper piston to wall clearance.

 

[BogusSVO]

Here is the steps to have a block bored at a machine shop.

1) drop of block to shop
2) shop rough bores block to size
3) pistons are ordered and received
4) Block is finished honed to sized and PTW is set
5) Pick up block and pistons from shop
6) Build short block

Now the old timer is remembering back in the good old days when manufacturing of pistons was sloppy and the piston size could vary as much as .002 in the same box.

With todays process of manufacturing of pistons tolerances are much tighter, common less than .0005

 

[goodhart]

^What he said. The right way to do it would be to measure the pistons to see what the cylinders need to be bored to, vs boring the cylinders without knowing the exact size of the pistons. Take measurements of the cylinders and the pistons and see if they still fall within the piston to wall specs in the factory service manual and the papers that came with the pistons.