502 GM crate engine Gen VI blocks - all same max bore?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
dave brode
Expert
Expert
Posts: 732
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

502 GM crate engine Gen VI blocks - all same max bore?

Post by dave brode »

Hello all,

I bought a std bore Gen VI 502 block, casting 319165956. I'm not sure if it is the latest version or not [which afaik, is part # 19170540 with same casting #]. It does have the bolt boss in the valley for the dummy oil pump shaft, and the std and corvette clutch ball bosses.

GM lists the current version being ok for 4.600", which afaik, is part # 19170540 with same casting #...956. I've seen older versions listed as 4.500' max. I've rread that GM was over safe with the smaller max bore size, and I've also read that the latest version is actually thicker.

My block has a small chunk out of the bottom of two opposing cylinders [flung a rod]. It has pretty deep rust in an adjacent hole, which I'm sure would take at least .030' to clean up the rust, maybe more. I'm torn between 2 sleeves and maybe a +.060' bore, and +.030" and three. My plan is to use a 4.375" Scat 2 pc crank that I have with a seal adapter and build a big dumb 5500-5800 rpm street engine for a truck.

Thanks for any advice.
Dave
rustbucket79
Guru
Guru
Posts: 2151
Joined: Fri Apr 07, 2006 8:23 pm
Location:

Re: 502 GM crate engine Gen VI blocks - all same max bore?

Post by rustbucket79 »

Sleeves in 4.500 and larger bore BBC blocks invite cracks to start leading from the head bolt holes due to the lack of parent material left. I would avoid sleeves in your block if at all possible.
Joe-71
Pro
Pro
Posts: 297
Joined: Sat Apr 08, 2017 5:46 pm
Location:

Re: 502 GM crate engine Gen VI blocks - all same max bore?

Post by Joe-71 »

A professional sonic test is cheaper than a sleeve install, and you will erase any doubts as to the quality of the block. Joe-71
Joe-71
dave brode
Expert
Expert
Posts: 732
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: 502 GM crate engine Gen VI blocks - all same max bore?

Post by dave brode »

Gents,

I did plan to have it sonic tested. I just wanted opinion of how over-safe that was.

What i read about GM going to 4.600" on max bore was wrong, that must bre on aftermarket blocks [p292 chevy perf catalog].They still list 4.500"

The missing chunks are apx 3/4" x 3/4", facing each other, so one on the major thrust. Esp with a 4.375" crank, I am leery of running it as is with just an overbore.

Thanks
Dave
dave brode
Expert
Expert
Posts: 732
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: 502 GM crate engine Gen VI blocks - all same max bore?

Post by dave brode »

I had a reputable machinist/engine builder peek at it. He said bore it to fix the rust and run it. No sleeves.

Thanks to everyone.
Post Reply