I have an 817 block (400ci) that has a 040" overbore it appears. On the timing chain side I found a "5". On the flexplate side I found an "H4". Anyone know what they stand for?

I just took it apart, stock crank and rods, and dished pistons. Also came with some 493 heads that I might mail to RB83L69 with no return address.

What are the chances I can bore this out 0.060"?

Taking to machine shop next week for parts checking and cleaning.

 

Most engine builders will frown on .060 on the 400 block. The only way to be somewhat sure would be to sonic test the cyl walls on the thrust side to see if it meets the minimum thickness.

 

.060" over isn't real likely; but if they can sonically check it, you might get lucky. Maybe a quarter or a third of all 400 blocks will withstand that, and not hit water or otherwise fail. I don't know that any of the 3 possible casting #s are any better or worse about it than any others; it's more of an individual thing.

If it doesn't really need bored, you might want to just try to work with it like it is.

 

Thanks. I realize that. I might just re-ring it and put new bearings in and go like that for a while. Running "loose" makes more power anyway, right?

Wanted to know if anybody could tell me what those numbers are. Not important anyway, I reckon.

 

Most guys are not aware that quality piston manufacturer make pistons in .045. A ring set is also available to match. It is typically 100 extra bucks(approx) to get a set of .045's. Check into this with your engine builder. If you need more details I can provide them.

 

You can order pistons in virtually any bore you want, from the people who make "custom" pistons; JE, SRP, Venolia, Arias, Mahle, etc. etc. It's just a matter of $$$$.

It doesn't make a whole lot of sense to buy a $1000 set of pistons, just to save a $250 block, though. Unless you were going to buy $1000 pistons anyway.

 

The pistons I am referring to are in the $500 range. The origional post asked a question, I gave him the info I felt he could use. Thank you for clarifying/correcting my post.

 

It's nice to know what my options are. I'll just have to wait to see what the machine shop says I can do with it. I'd like to use the block. 400s aren't easy to find around these parts, and an aftermarket block isn't an option right now...maybe later when I know what I'm doing.

Was only planning to use stock crank, rods, inexpensive pistons if possible...for a stock short-block rebuild. It'll be my 1st short-block build.

 

Gonna use the 400 crank in a 350 instead.

LPE 219 Cam
083 ported heads or L98 alum. heads ported.
deck the block ~0.020

Use 5.7" or 5.565" stock rods?
Please Recommend a good piston for either rod that promotes good quench. I can adjust the compression ratio fairly easily, have 4 sets of heads to choose from.

Thanks