HamadUP

Hi all,

I'm building a Gen V 454 engine out of a '92 GMC HD truck, I just came to installing the pistons rings (perfect circle brand) but I was surprised to find that the oil control rings wont fit the original pistons, the groove in these pistons is too shallow! the rings will stick out and wont compress inside the groove at all (the 1st and 2nd compression rings will fit just fine), this is my 1st time to work on a post Mk IV BBC engine , so am I missing something here? .. or do these engines use a different oil control rings?

427Hotrod

Good chance those pistons take metric rings.

JIM

HamadUP

so, where can I find the correct ones? whats the metric size of the correct ones?

what was wrong with SAE ring sizes so GM would shift to metric??? .. they just made my life harder! .. I was hoping I would fire up the engine on the end of this weekend

Ben Lurkin

zee book shows 5/64, 5/64, 3/16" for the gen 5/6 454 ring packs. (The 502 uses 5/64, 1/16, and 3mm oil rings) It sounds like the pistons may not be original You don't have the original rings from teardown to compare?

ikwhite

Well I am not sure if you need a metric size oil ring, but from what I recall the stock Gen V pistons do require a shallow ring pack and I assume that is what you need to narrow your search for. I had a chart somewhere and I'll see if I can find it again perhaps it will list the rings you are looking for.

ikwhite

HamadUP

OK, found the correct ones locally, I found hastings and installed them today, thanks guys