Hi all. I am the proud owner of a ZZ572/720R crate engine with a spun main bearing. Block ok, and crank will be ok when turned .010. I have one bad main cap. GM does not service these caps seperate from a block assembly. ( Gen VI bowtie block with splayed outer bolts.) Anyone have a source, or perhaps know of someone who has kicked a rod out or otherwise ruined a block who could supply a cap? All help sincerely appreciated.

were you using it in a boat? what kind of boat: lenght, twin, single etc...??? if so, how many hours did you run before that breakdown?

I know someone who dropped a valve and destroyed on in a chevelle I'll give him a call and see what he has for parts. It was about a year ago and I know he went a different route with the engine. Not sure where you are located but jan cen racing in west Seneca ny (buffalo) usually can come up with some parts give them a call they are great guys

It was in a car.

Thanks very much! PM me if he has anything.....

i broke a main cap on a mark4 gm bowtie block,cap #4,my machine shop got the 3 center caps,aftermarket,and installed them.they have a rottler machine that bores them right to size,the engine now is a 588 with 8.3L whipple making north of 1200 hp.where are you located?

Back already jim?

I am glad that you were able to resolve that bad situation. In my case, the OEM outer caps have splayed bolts, not the straight ones like your Mark 4. They are the only OEM big block caps that are splayed, even Mark 6 454's & 502's have straight outer bolts. The Milodon splayed caps are splayed at a different angle. I have contacted Dart & World (Merlin), and theirs are not correct. Howards, & Oliver are straight outer bolts. I sent Pro Gram the bad cap, and at this moment they are my best (only) hope unless I can find a used 572 cap.
Irregardless of what (if any) caps I come up with, they will have to be aligned bored - that is not the issue right now - the block is sitting at the machinist awaiting a cap. You were fortunate to have a Mark 4. Used and aftermarket caps are everywhere for Mark 4's, in fact GMPP supplies them new for Mark 4's. Thanks for your input.

CaptainCrunch:

Not for sure this will help, but PAS Performance Assembly Solutions in Livonia, Michigan assemble the 572 GM performance crate engines for GM Performance and I would think they might be able to help you with a cap or how to secure one. Their phone number is (734) 466-6380.
Hope this is a help.

Regards,
Ray

Hi Ray. I became aware of PAS thanks to a post you had submitted several years ago. I talked with a gentleman up there yesterday. They get the blocks & caps complete from a foundary called J&B. He would not give out any info on J&B, and I have found nothing on the web. He said he would see if they (PAS) had a defective block around that he could scrounge a cap from, but "wasn't promising anything." Thanks for taking time to post.