Gauge

iTrader: (3)

Howdy all,

I'm rebuilding my LS1 (stock cubes) with -9cc Mahle pistons, Compstar rods, and my stock crank in hopes of running NA for a few months and then getting a Procharger. This is my first rebuild, and I'm looking for some advice. I checked the gaps on one set of rings, and here is what I found:

1st ring: .007" gap
2nd ring: .011" gap
Top oil scraper ring: .032" gap
Expander ring: I hope this doesn't need to be measured, cuz I dunno how I'd do it.
Bottom oil scraper ring: .032" gap


Now, here are some questions...

1) What gaps should I be looking for?
2) Can I expect the same gaps out of all the other rings, or will they vary widely?
3) If I have to file the rings, what tool should I use to do so? Price is a big factor.
4) Where can I get the tool from question #3?


Thanks in advance everyone. I'm getting really excited about this rebuild!



P.S. - Moderators, I put this thread in the Forced Induction forum and then thought it might belong here. If one needs to be deleted, go for it.

Irocss85

iTrader: (1)

well, things might be diff. in LS1 land, with the alum. block and all, but for an iron block eng. typical top ring gaps are in the .019 range for N/A. but if your building for FI, thisis a very important step since the heat from the boosted charge will require larger end gaps. be prepared to file ALOT to get gaps around .023". but as Ive said, Im not an LS1 guy, so just consider this a general idea, and you still need to find out what is best on an LS1 engine for handleing boost. the second ring will be a bit tighter, to help hold in all the pressure and not bleed off the boost either. the second ring will not see the same temps as the top ring, thats the reason why it needs to be smaller.
Im sure you can leave the oil scraper rings/spring alone. as for the spring part of it, just make sure it doesnt overlap itself when its on the piston. its prolly got plastic filled ends to make sure this doesnt happen, but just something to be aware of.
if you can find one, use an electric ring grinder. trust me, I used a manual crank grinder to set the gaps on my file fit rings (set at .023 for nitrous use on my LT1) and I would crank that F'n wheel 100 times, retest gap, crank it another 150 times, test fit gap, and so on till it was there. man it took an eternity with the manual crank wheel. summit sells ring filers if you cant find anyone local to borrow one from or rent one from.
maybe try machine shops in your area to see if they'll rent there's out? and, dont forget to dress the ends of the rings that you have filed down. basically get all the new edges chamfered BEFORE inserting the ring in the block or on the pistons cause it will scratch up your cyl. walls and possibly chew up the ring lands in the pistons.

and you prolly already know this, but you gotta set the ring end gaps for each cyl, the bore will be diff. for each one by a thou or two so you should set each one seperatly and keep the rings in order as to which cyl they go to.

Irocss85

iTrader: (1)

oh yeah, and the reason they have the gaps soo small now is so that you have to file fit each ring to fit its cyl. bore.

just curious, how are you putting the ring in the bore to measure it? it should be about 1" down the bore, I slid them in, and use a piston to "square" the rings in the bore. it absolutly needs to be sitting in the bore right for the gap to be measure accuratly. if you take one of your old pistons (same bore size right?you didnt mention larger pistons) and leave the second ring in but take the others out, it will be expanded out of the piston larger then the bore, when you slide the piston in upside down to push the ring squarely into the bore, the old ring will stop the old piston from goin past the second ring land as the old ring acts like a shoulder to keep the piston from goin crooked. I hope I explained that good enough for you to follow.

Gauge

iTrader: (3)

Wow, that's awesome info, Irocss85. Thanks so much. Seriously, that was a great read and answered a lot of my questions.

I'm hoping I can rent a ring grinder from Auto Zone. Anyone ever looked into this before?

V6 Bird

iTrader: (15)

Are these file to fit rings? How did you measure end gap on them if so?

I ran .022 top ring gap and .026 on the second ring. and didnt modify the oiling rings.

I used a small cat tail file to fit my rings. be sure and deburr the ends as well before installing.

willyfastz

You don't have to rent a ring grinder, just buy a new small flat file and clamp it in a vise.

Irocss85

iTrader: (1)

never actually tried to remove material with a file, wonder how fast that works compared to the manual crank file I had borowed? it would have to be of the fine tooth style. what ever way you choose to file the rings, pay close attention to geting the ring "ends" square also. a ring filer has guide's built into it to help with this.

also, I forgot to add that the ring filer i was using might have been dull. causeing LOTS of revolutions to remove a little material. ohwell, you'll enjoy the experience when your done, and will love the fact that you did it yourself.
good luck man.
chris

JDM74

You should really contact the ring manufacturer as to what the ring end gap should be set at regarding your setup. I know the Mahle rings I have reccomend that a torque plate be installed during fitting of the rings.

Irocss85

iTrader: (1)

i could see tha I guess with an alum. bock due to the cyl. being pulled out of straight (maybe). couldnt hurt to call them and see, but it sounds to me like thats really splitting hairs to make it exact. worth the call for sure though.

Id be curious to see who else has/hasnt done this while fitting rings for there LS engines.

GuitsBoy

iTrader: (4)

Id be real surprised to see any appreciable deformation of teh block without a torque plate.

I bet you could mount a dremel in a vise and grind the rings with the reinforced cutoff wheels.

Studytime

iTrader: (15)

Well, with the torque plate installed it would barely have any affect on the ring size. The affect that it did have would be small and would be rounded to the nearest thousandth, but guess what? Filing piston rings is not rocket science and it's not like making a rolex. The rings are going to be off somewhat. If you're targeting 18 thousandths for your top ring, chances are your rings will fall anywhere from .0175 to .022"- all of which would be fine.

Ben T.

Jason99T/A

iTrader: (21)

The LS1 aluminum blocks are real bad about distorting at the top of the bore without the torque plates installed. With the plates installed, the bores "grow" as much as .0015" , which will effect ring end gap considerably (~.004").

Do you need them installed to file rings? No. It just all goes back to the quality of work your are trying to build.

The iron blocks aren't quite as bad, but still enough where I won't take this into account.

Jason