I'm looking on Summit for parts I'm gonna need to replace for my engine build, its a 87 350 roller, 4 bolt main, 1 pc rear. I'm gonna use stock LT1 pistons and rods, I'm looking at bearings and rings and I had a couple questions. Do I want "chamfered" rod bearings or no? What's the difference? As far as piston rings, what size rings do I want? Is there an easier way than measuring them? Thanks!

 

what do you mean by the size....both dementions (thickness and diameter) are determined by the piston, you need the same overbore as the piston and the same thickness as the piston grove, the only option you really have is the coating and to some extent the sealing face, you also could get gapless rings from total seal, which is what I'll be using when I do my re-build, the only problem is you need absolultly strait bores to use them.

 

Ahem, yes I should have been more specific, I need the ring thickness for all three rings. Is this highly variable? Should I just take out the old rings and measure it? Thanks!

 

the 2 common sizes are 1/16" and 5/64", I belive 5/64 was the stock size for gen 1 blocks, but i'm not 100% sure, I'd say mike the old rings and use that size....have you had the block looked at yet by a machine shop....it needs to be at least finnish honed or the new rings won't seat, and depending on the wear it may need to be bored out to a standered oversize, in which case you'll need new pistons and matching rings anyways.

 

They block was machined very recently before I bought it...looks great. I'm just calculating the costs of everything beforehand, so I can starting saving So would that make it 5/64 (or maybe 1/16) for both top and bottom rings? Thanks, and any idea about the bearings? Chamfered or no?

 

measure the ring groove or an old ring. it'd be a lot more effective than asking on here.

 

I've been told more than once, lt1 pistons use metric rings.. But they could have been confusing them with LS1..

Stick a ring in it. If it fits, measure the clearance. .001-.003 is acceptable. More causes flutter. Less could cause the ring to stick..

Then you'll want to check your piston side clearance.. If its greater than .035, forget it. Also make sure the bores are perfect. If you got groves and pits, you'll get a bad ring seal.

Blower? nitrous? N/a? Choose your ring gap.

You don't need chamferd bearings. Check your clearances, and run the appropriate size clevite 77 bearing.




-- Joe

 

Thanks for your response, that's exactly what I needed to know. What are chamfered bearings used for? I've got old rings in the pistons now, so I'll measure those. The block I've got has been machined already, but I guess it would be a good idea to check the piston clearance myself. The cylinder walls look pristine, no pits or anything. This engine will be N/A, so gapped rings are ok, correct? What applications do you use gapless rings for? Thanks!

 

gapless rings are for all apps. they increase engine effecincy allot, but require the cylender walls to be perfectly true, there can be no taper and the block HAS to be done with a deck plate, by the way you said your block is machined already, do you know to what size, you have to use pistons/rings that are matched to the overbore that your block was machined to (.010, .030, .040, .060 are common overbores), you can't put stock size pistons/rings in an overbored engine.

 

According to the guy I bought the block from, it hasn't been overbored. I am however going to check this at some point, before I start buying parts.

 

the only way it can have a fresh machined surface is if it's a brand new block....and the factory was never verry presice in there boring/honing process, and they diden't use a deck plate, to simulate the heads being bolted on, as the torque on the bolts accuatally distorts the cylender walls, causing them to go out of round and losing power, the way to fix this is to use a deck plate and bore/hone it with it on which will ensure it is true when the heads are on it

 

I would hope he'd forget it. That's enough clearance to fit a third world country into.

I hope you meant to type .0035", but even that seems a bit excessive, except for forged pistons maybe.

 

Yep. Was in a rush to get out the door and didn't hit the zero key quick enough.

-- Joe