I'm rebuilding a '91 Camaro 350 (LB9). Engine code (8).

I've contacted a Chevy dealer, parts supplier, and Jegs.

They can't agree on the correct set of rings that I need for my pistons.

Jegs tells me that I need to give them the sizes in metric
even though the catalog shows it in 8ths, 16ths, or 64ths.

The other suppliers tells me that their order sheets show that it's an LT1, not an LB9.

This is my first rebuild, is there something that I'm missing here?

Any help is welcome.

 

www.summitracing.com

Do a part # search for SLP-E-356X, Sealed Power cast rings, $21.99/set ("not recommended for performance applications").

Or, SLP-E-356K, Sealed Power chromemoly rings, $38.39/set ("for stock or mild performance rebuilds").

Add "030" to the end of those p/n's if .030" overbore.

No clue why anyone is talking about "metric", "LT1", etc.

 

Exactly... if your pistons use the stock ring configuration (which they will if they are virtually any cast or hypereutectic ones, or most off-the-shelf forged ones such as Sealed Power) then they will be the 356K. Don't use the X, they are junk, intended for non-performance grocery cart "gee boss I always wanted to build a motor" type of jobs.

Just FYI, they're 5/64", 5/64", 3/16". Nothing metric about them.

 

are all 350 pistons rings the same for stock bore. cuz i have a .30 over 350 i am thinkin about puttin rings in and sellin the motor. i hate to waste the new crank, intake and cam i put in it.

 

If you want to keep the crank, you don't have to disturb the rings... just change the crank.

 

i thinku missunderstood me i want to keep the crank i put it there cuz its new and the piston rings in there broke so i was gonna go the cheap route and put oversized rings on my already .30 pistons. what size would i need. i was gonna base my purchase on standard size and do the math but if u know what i need then all the better. once again .30 over pistons with oversized rings what do i need?

 

If the rings are .030" over, then so are the pistons and the cylinders. You need the E-356K-030 set.

 

That's the 305 p/n. 350 would be 251K.

 

I finally found the right rings for my pistons.

They are in Metric and they're 2.00mm, 1.50mm, & 4.00mm.

They fit perfectly. So this weekend the crankshaft, bearings,
and pistons (rings included) are going in.

Thanks for your help!

 

i sure don't know much but i've never saw metric size rings in a thirdgen stock replacement or aftermarket preformance. what pistons do you have?

 

I also just realized you gave contrary information in the original post.

"350" and "VIN Code 8" are consistent, but it's not an LB9, it would be an L98.

Are you sure exactly what you have there?

 

Sorry for the confusion. This is my first rebuild.

I currently have a 1986 IROC with a 5.0L LB9(305) and I'm rebuilding a 1991 5.7L L98 (350) engine to put in there.

I was also surprised when JEGS told me that they need the gap sizes in metric (I thought that the Tech was just trying to blow me off) .
So that's when I went to a local parts supply house and sure enough they showed me on the screen that the compression and oil ring gap sizes for a 4.00 stock piston were in metric.

Well anyway, I put in the crankshaft, bearings(with assembly lube), and pistons in over the weekend and everything fit perfectly.

This weekend is the front and rear seal, and the heads and then this Spring when the weather is kinder, I'll swap the engines.

I'm not swapping the cam out yet, because I don't know what's in the 305. If it's better and compatible, It will go into the 350.

 

The '86 cam will be a flat-tappet lifter design, and the '91 roller lifter. You really want to keep the roller design. Although more expensive, a nice computer-compatible grind from Crane or Comp will be a big improvement over either factory grind.

 

2mm, 1.5mm, and 4mm might be the ring end gaps in metric but i doubt that is the ring size. like was already said the 1st and 2nd grooves are the same size and the oil ring is wider.

 

I was going to make a whole new thread but instead I used the almighty search button and what I found well less than good

I have revived this post from the dead because I can shed some light on it and I am also at a loss myself but in a different way.

First of all let me start by saying for many GM V-8's (305 or 350) produced 1990 and later are equiped with metric rings. Not the regular 5/64", 5/64", 3/16" but instead a 2.0mm, 1.5mm, 4.0mm.

The only reason I know this is because I am very familiar with the changeover to metric rings in 5.0 mustangs years ago and also a little nugget of info about it stuck in my head from a car magazine article from years past.

Imagine my surprise when I pulled apart my 91 Z's L98 to find a top ring that was visably larger than the second ring. That little nugget came up and immediately I thought "ok so their probably metric".

So a little checking later and I find out that not only that they are metric, but almost nobody carries them and 99% of the parts stores computers and catalogs list the "wrong" 5/64" rings. Those that do carry them are unfortunately prohibitively expensive.

Litterally I can buy a set of name brand cast flat tops WITH rings new from some of the suppliers that sell on ebay cheaper than I can get the rings.

I have checked with all of the usual suspects, and if you know someone that carries cheap rings the part numbers are:

Hastings 4626

speed-pro/sealedpower E350K

Im looking for STD (standard) bore but if you are looking for some in oversize additional numbers get attached to those two above I guess.

 

Guess what? I decided to look into this further (should've back when I built mine) and found that the LT1 rings are the very same thing. 2.0, 1.5, 4.0 mm. Still quite pricey, looks like stock replacements are aroung $120-130 (guestimate based on what our cost is through the shop).

The Federal Mogul part no is E530K, then add 20, 30, 40, for oversize. Why are they so much more expensive? I wish I knew!!!

 

I think it has to do with the volume of them. I have found some rings in the $70 range, still looking.

 

I have been looking into this as well, and my 91 Corvette L98 with flat top short skirt pistons has the two different thickness metric rings. Basically it is an LT1 short block, or the same as what comes in the current ZZ4. From what I have read Corvettes of the era offered different compression ratios, as an option. The flat tops with the Alum 58cc heads yielded 10:1. As has been documented many times, in the Camaro assembly runs if the flat top short blocks were all that were available on any given day they were what went in the Camaro. That said, from what I can tell the only rings available for LT1 are moly rings, but I have seen them for around $65. I haven't purchased yet ...still gathering info to make the right choice. I have seen .005 over size for a stock bore re-ring though.

One thing to remember is the LT1 pistons are much lighter than old style stock replacements. If you use the replacement ones it will unbalance your motor, and it cannot be re-balanced because the crank lobes are already too light. To change to stock pistons You need to use a matching crank.


One other thing I am hearing is that with moly rings a simple "de-glazing" on the cylinders with a bead hone won't work. A properly honed block is needed.

 

I thought I found a cheaper set but the price was for each piston!!!