WTF !!! what's the deal with ring gap ?!!

blacksmoke83

blacksmoke83

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Oct 26, 2008
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In accordance with the information I found on CompDiesel and what is written on Mitchel OnDemand5, for the top ring, the gap should be more loose then the second one, right ?!! So now, I got brand new 0.020 Mahle pistons and rings and I got 2 sets of brand new 0.020 Cummins ring sets, both brand got the gap of the second ring more loose then the first one by about 0.020''-0.025'' that's a lot !

Is there anybody who can tell me what the deal is with these ?

Any help would be reallu appreciated ! :Cheer:
 
Second ring gap, should be larger than top ring.

Cummins spec,

top min .011 max .023

Intermediate min .035 max .054

Oil min .011 max .030


Lean to the max side if your going to be beating on it.
 
Last edited:
Thank you very much man ! that's what I thought ! So, what kind of ring gap for a 700-800HP daily driver engine ?
 
As a recomendation I know you will get away with .023 top and .035 second and not worry about the ring ends coming together, BUT you might have a little more blow by than your used to.


The ring packs that came from cummins for my steel monotherm pistons out of the box were .030 top and .054 second, and I thought it would be a blow by monster, but its hardly more.


Whats your piston to wall clearance?
 
blacksmoke83 said:
.028 for top ring, .049 for the second and about .030 for the oil ring
Click to expand...

I took new measurement today, and finally it's about:

top: 0.29
2nd: 0.53
oil: 0.026

What do you mean by (a blow by monster, but its hardly more),is it
streetable, or Ill have smoke coming out the breather pipe all the time ?


Should I just go with an other set of ring ?

Thank's !

Steve :Cheer:
 
blacksmoke83 said:
I took new measurement today, and finally it's about:

top: 0.29
2nd: 0.53
oil: 0.026

What do you mean by (a blow by monster, but its hardly more),is it
streetable, or Ill have smoke coming out the breather pipe all the time ?


Should I just go with an other set of ring ?

Thank's !

Steve :Cheer:
Click to expand...


Well ideally, I'd like to see it more tight, but I can tell you thats pretty much the same gap I ended up with, and blow by is good, only slightly more than when it was stock. (I keep records with a manometer) Unless you measure it you would never know the difference.

You'll be fine.

There is the total seal option for the second ring, but I wouldn't do that in a DD.
 
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