New 502 blocks...need finishing?
 

Does a new 502 block that comes with a 4.466 bore size need any additional work for a stock JE piston? My shop thinks it will be too loose after plate honing.

they are probably right... but i would have to ask if they have bolted the plates on and confirmed that the bores move in any meaningful way and as such NEED plate honing...

the only think i ever did to blocks that had the right dimensions from new and didn't move when plated was brush hone them to get the finish that that particular ring pack wanted.

Thanks Steve. I just wanted it plate honed myself. The shop says a plate hone removed ~.0035, which sounds more like full blown hone to me. I had a 454 just plate honed at another shop after it was used for a little, and could swear they only took .0005 out of it, and that fixed the oil usuage problem.

I cant see why GM leaves these at 4.466, knowing that they have to be taken out further.

Vince,
Most piston manufacturers recommend at least an additional
.001" clearance on a raw water cooled marine engine anyway. It rarely takes more than that to clean up the bores with a plate bolted on, especially on the big blocks. It does vary from block to block. I have yet to see a Dart block move even a tenth when a plate is bolted on.

Personally, I would be more concerned with the bore finish than the size. Dont get me wrong, the correct size is very important but I have seen some pretty terrible finishes and that is what is the most imortant as far as ring sealing.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

It is worth it to have a good machine shop go over the entire block.... just to be sure.

Chris

So Bill, you comfortable with the stock JE piston in these new blocks? The new blocks are supposedly stronger, and have a fuel pump boss. But if a rebore is necessary, I might as well keep the current block I have.

Vince,
What are your plans for the engine ? I have not seen any issues with the stock JE pistons.

Bill

Yes. I always find that they need to be align honed. They align bore them from the factory and that is not good enough for me, since the housing bores will vary a little in size. I am very particular on housing bore sizes. I want just the right amount of bearing crush, so I always align hone a new block.
Eddie

What I meant Bill was the fit of the pistons in the bores - will they be tight enough after a hone. The JE are forged, so I know the'll hold up, no nitrous or forced induction here....yet :D

You can put a torque plate on and hone a new block. You want a extra .0005 to .001 clearance for marine use. If you measure the pistons and figure at least .006 clearance you will be ok.