how can I tell what engine I have
 

need to replace 502 block in a 1999 Baja. have engine out, how do I tell what generation block I have. does it make a difference? I would like to put all of my internal parts in a new block. The one I have was frozen and cracked

Thanks
ps. also looking for block-short block

yes it certainly does matter!!!!

tehheads won;t fit on wrong generation blocks. If you look at teh casting numbers on it you cna look them up and it will tel you what gen block it is. Give it a few hours someone will post the links to the casting number lookup website. I woudl have your internals checked out before you plop them in a new block. Might as well. Its better to find problems now before you spend a ton of $$$ puttingyour engein back together.

Are you looking fr a short block or a bare block???

I believe all the 502's were either Gen 5 or 6, both of which use a 1 piece rear main seal. The Gen 5 did not have provisions for a mech fuel pump but most Gen 6 did. The Gen 5 had stamped steel timing cover and the Gen 6 used a cast alum cover.

I believe the Gen 6 heads could be used on any block, Mk4, Gen5. But the Gen 5 heads could not be used on earlier blocks. Dennis Moore's book will answer all your questions and is an excellent resource. There was a thread earlier today with info on how to order the book.

Good luck, Todd

I may be wrong about heads. The Mk4 heads could be used on Gen 6 motors but not on Gen 5. If Dennis Moore chimes in he can tell you how to get his book.

Gen V or VI
 

The only differences between a Gen V and Gen VI are the timing chain cover (cast aluminum Gen VI, stamped steel Gen V) and the roller camshaft (comes in the Gen VI). Everything else is the same.

GM had a new 454 crate engine on display at the SEMA show last week and I asked a GM engineer if the 454 was ever going to come with a fuel pump boss (like they advertise) and he said no.

Dennis Moore
BIG BLOCK CHEVY MARINE PERFORMANCE
626-675-3548

pachanga

502's also came in two variations of MkIV's...

Early ones came with a Bowtie performance block and 1990-1992ish came with a siamese MkIV block with normal pushrod-driven mechanical fuel pump boss.

mcollinstn, I knew the 502 was available in the Mk4 Bowtie but I was not aware that it was avail. in the std Mk4 in '90-91. Thanks for the info.:)

ok if I understand per Dennis, you should be able to use gen. 5 in place of 6, and just wouldn't need the mech. fuel pump hole.
I just checked, this engine has roller lifters,alum.time cover and no hole for mech fuel pump. so its a gen. 6 ? correct?

Here You Go;) ;) ;)

Casting numbers

The fact that you have the aluminum timing cover (with only 6 bolts), and it is a roller motor(assuming it is factory), combined with the fact that your boat is a 1999 and the assumption that it is the orginal motor in the boat, would indicate that it is indeed a GEN VI.
How is that for run-on!!!:D