[dell72]

So I purchased a brand new Gmpp Gen 6 502 block. I bought it from a private owner, new in the crate. My plan is to add a 4.250 stroke crank and leave the bore standard. This is the revised Gen 6 with the mechanical fuel pump boss, revised oiling and main bearing bulkheads. Does anyone know if these blocks are rough bored and need to be just honed to the piston. It has freeze plugs and cam bearings in it but no oil gallery plugs. I'm curious how much prep work is needed to run this block. Thanks for the info

 

[CPMotorworks]

Pistons will vary in size, also probably wasn't honed with a plate on it.
BTW..call this guy
http://milwaukee.craigslist.org/pts/3910135917.html

 

[CNC BLOCKS N/E]

Pistons will vary in size, also probably wasn't honed with a plate on it.
BTW..call this guy
http://milwaukee.craigslist.org/pts/3910135917.html

GM don't believe in honing with plates here is a pic of one of there performance blocks.

 

[GOSFAST]

Hi Eric, assuming it's a new block (as delivered from G.M.) you will need to have it finish honed with a plate. You will also need to have EVERY other dimension checked before you start laying out the program.

Most will need decking as well. The ones I have here are already "square" but they are slightly high from the 9.800" number. I have built some with the decks "as-is" with no issue! Depends on the platform and the customer.

I have about 4 of these (MK-VI style) here now based on the 4.250" bore, and I have a bunch of the BB 4.500" Bow-Ties (MK-IV) as well. Most are all in their original boxes from G.M. Some have been started on their builds.

I have no "502's" handy but on the 4.250" bores G.M. leaves the bores (unfinished) at 4.244" (nominal), and the 4.500" designated bores start at 4.495" "as-delivered".

Most of our builds end up at .001" over the "standard", e.g., 4.251", 4.501", etc.

We haven't found it "mandatory" to correct any of the main bores, cam holes, or even the lifter bores, they are normally fine as-shipped. This is our own findings. I use a number of these castings, mostly the 4.500", MK-IV style, S/D though.

I do try to avoid any other brands and stay with G.M. but occasionally my customer's will request the Dart line.

(Add) I really don't care for the 1-piece rear main seal setup, it creates other issues for us! I prefer the MK-IV deal when possible. I have used a number of rear seal "adapters" to convert the blocks with excellent results.

Thanks, Gary in N.Y.

P.S. You really need about .005" minimum material to remove (we prefer to see .006") to get a good base finish on the end bore size. We've had no issues to date with ring seal!

 

[dell72]

Pistons will vary in size, also probably wasn't honed with a plate on it.
BTW..call this guy
http://milwaukee.craigslist.org/pts/3910135917.html

Is that crank strong enough for big horsepower applications

 

[badrad]

What happened to the oval port 454? A 540 is such a different animal, what heads to you have in mind?

 

[dell72]

I found this block and it was a good deal. I'm going to do a 540, hyd roller and i'm thinking about going with AFR 305's.

 

[badrad]

Should be a stump puller!

 

[dell72]

I was reading an old build post by mike lewis on a 540 that made around 730 hp and over 600 lbs of tq. That would be awesome!

 

[badrad]

That's a lot of engine planned but why stop at 540? You could put a longer stroke in it for a bit more. What will you have to do to the rest of the car?

 

[modchevelle]

Eric that block is no good....Ill take it off your hands. LOL Good build and take pics and keep us up on things.

 

[dell72]

So I called Chris Straub today. I ordered AFR heads, custom hydraulic roller and Morel lifters. I can't wait!

 

[Busted Knuckles]

Take the block to a shop with a sonic tester and have the cylinder walls checked. I've seen two of the later 502's with the same cylinder walls as a Bowtie block - plenty to bore to 4.600.
Good luck with your build...and buy stock in your favorite tire company...