I'm not a motor guy so I really can't answer a bunch of questions, very limited knowledge about my car other than it is a numbers matching 1969 442 with a 400 G motor. I'm having the Engine rebuilt and the machine shop is having trouble finding pistons. He tells me it has the smaller pistons; he's boring it .30 over so needs to find pistons that are 3.900. All we've been able to locate is 4.030 pistons and those are too big. I spoke with Summit Racing, and they don't have a listing other than the 4.030 pistons. Any links or info would be helpful. Thank you

 

Have you looked on Ebay? Also try Kanter for parts.

 

Contact Mark, a member that is both a piston dealer and an Olds engine builder:

https://www.truepeoplesearch.com/find/phone/8632063320

 

eBay does list some 400G plus 30/1000” pistons sold by Kanter brothers but I would first call Mark to explore all your options.

 

Kanter and Egge pistons will be cast. I'd go with forged.

 

Olds Performance, list a set $700

 

I know for a fact that Egge supplies pistons in exactly the size you want because I used them in my 400G. However, as Joe points out, they will be cast. Back when I did my build they were the only ones I could find. There may be better alternatives now.

FWIW, I have no complaints with mine. For a mild street build I have found them perfectly acceptable.

 

Here is a set of .040's. I would buy them quick for that price. No difference boring 30 or 40.
https://www.ebay.com/itm/37606939375...Bk9SR-bbzp7GZg

 

Except there are only four pistons in that auction ad.

 

I guess I didnt look close enough I would almost bet that pistons are out there though. Probably not that hard to find. Ill put out some feelers.

I have used several sets of Egge's pistons and they have been fine too.

 

I have a set of AutoTec forged pistons that came out of a previous 400G build. I highly suspect that block was bored when built but can't say for sure - I'd have to measure it. If you're interested, I can measure the diameter of one of the pistons. Note I have 8 but one (or two - I don't remember) were damaged during disassembly. The rest are OK.