I know this might be a stupid question, but what is exactly a GM crate motor? Is it what it sounds like, a rebuild standard automotive longblock?
I am new to the US engines and need to learn.

Thanks if you take the time.

GM makes lots and lots of long blocks, some are for cars, some are for boats.

Those for boats are sold to different companies who put their hardware, ie. a Volvo 454 and a Mercury 454 both start as GM 454's.

The crate moor is basically a new motors from GM.

Thanks dean that`s what I thougt. Just a nother question, a crate engine, like yours, when ordered would it be spesified that it is for marine or car? Would the engine have been by mercruiser?

Dean,
As Smitty said, those domes look big. What is the compression ratio?
Vinny

Yes, crate 502's have smaller domes (by the pics anyway), but these are 454's right ?

yes, they are 454's, I did not know they were large dome pistons until we pulled the head.....

Are they GM crate motors or Runsnew.com, or whatever their name is? I thought that's what you have.

Could Articfriends be onto something? That would give you the bearing trouble you have.

I have read his stuff, WOW, it is amazing....

these were just basic stuff, so we used merc stuff for them, ALL new, everything, if oil went through it or it controlled oil, it was new.

I planned on getting it running right, and then upgrade one piece at a time so I could moniter how it helped or did not help the engines.

I deal with an engine guy since many years. Does all his balancing, grinding himself, + he assembles the engine. All done at his shop. If something's wrong, it's his fault. If it goes well, it's also his fault! But I never ever had any problem when he builds an engine. crates are cheaper. but maybe you'll have to find a place similar to my guy: 1 stop shop, for marine application. Best of luck...