gcb951

I bought rings from Lindsey Racing and they are supposed to be pre-gapped. Is it nessessary to check the gap on them before installing?

Kool

How does one do that?

Mike Lindsey

We don't have "pre gapped" rings.

You absolutely must check the gap. Place the ring in the bore. Push it down using the top of the piston about a inch. That squares it up. Measure the gap. We do .015-.016" on 100mm. If you got the Goetze, good chance your big on the gap already so just verify. Nothing you can do about it if to big. Porsche rings (4 x the money) will be closer to the desired gap to start with.

The more cylinder wear, or if you honed, the bigger your gap.

Van

Here's how I did it for my 914: http://www.ephotomotion.com/914engine/page14b.html

Different measurements, but same process.

Mike Lindsey

Van - Hastings had a ring pack for your 914?

pk951

Asking about ring gaps talk about neophyte you got *****.

Van

Sure - when you use non-stock pistons and non-stock bore sizes!

gcb951

Okay,

I thought they were pre-gapped. My bad.

So your saying that the aftermarket kind has a wider gap to begin with and that there is nothing I can do about it. Is it okay to have a wider gap so long as its close?

Basically I just want to make sure they don't overlap inside the bore right?

BTW: I did have it honed.

Lemme know.

Mike Lindsey

You want the proper gap but it's not always possible. If your rings are Goetze, they seem to be larger then what you want out of the box. They could be .020-.030". Loose, but you can't do anything about it. If you spend the big bucks for Genuine Porsche rings, they are tighter out of the box and sometimes dead on. You would still check them to make sure they are not tighter then .015" and file if necessary. Having honed or enlarged the bore, the gap increases. In your case, just measure them to make sure they are no less then .015" and move ahead.

gcb951

Alright,

Do I only measure the gap at the top or should I check near the bottom too?

Do I measure the gap of the oil ring too or just the top two?

Thanks for the help.

Van

If the gap changes between the top and the bottom of the bores, you have issues with your machinist. The bores should be straight and true.

Just the gap of the top two.

The piston rings expand when they get hot (by quite a bit) - if the gap is too small, when they expand, the ends will meet, push against each other, bind up and eventually cause the ring, and/or the piston lands, to break.

Mike Lindsey

"Hopefully" your cylinders are straight. The piston isn't but don't worry about that now. Top and 2nd ring should be as stated. Oil go with .025-.030".

Voith

Does anybody have the information on what is the proper ring gap and gap position for Andial Mahle 104.5mm turbo pistons?

grumpyf14d

Just like was mentioned above. Very important to fit rings to each cylinder for best results. Purchasing oversized rings is always the best way to go, then just file them down. Filing rings also has to be done with care because you can do some real damage if done incorrectly. There are a few formulas out there that tells you what the gap should be for upper or lower rings. Below is an excerpt from Wiseco, many of the ring companies also have formulas on their web sites if you'd like to check. Also also mentioned above, hopefully you are confident that the cylinders are not tapered because your ring gap could be affected if not done square. According to this table your ring gap for the top ring would be .020 for a Street-Moderate Turbo [ (100mm / 25.4) (.0050) = .01968].

Voith

I'm specifically interested in 104.5mm Andial/Mahle Turbo pistons. I have this, but this is for newer version of Mahles, I wonder if it is relevant for my rings too..



Cylinder was bored from 104 to 104.5mm and is ready for pistons

https://rennlist.com/forums/944-turb...it-look-4.html