• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Ring Groove Clearance

My military manual says Top .003-.007", Second .002-.003" Oil ring .002-.004"
I don't have my GM manuals here so I can't say about them.
 
Hink and I were speaking before the post. My Hummer manual has same spec as that from NVW.
Now, it makes sense because newer AM General aka Hummer is using what they had on record. But if the ine source to military is off, all of it would be off.

Hink has a GM 1993 manual that had different spec.
@Hink please post the picture of that here.

Can anyone please post any literature they have on it?

As pointed out by WarWagon, there have been other misprints.

Anyone have all data maybe?

I have always grabbed whatever book was at hand. I don’t remember tolerances- never try to on purpose- I always read the spec like 5 times while building.
Finding which is right is good not just for a few of us rebuilding right now, but everyone the builds afterwards.

Anyone that is running a recent build might want to open and correct before catastrophic failure occurs...
And on that note- always write and keep your actual specs as you do it for future. Maybe you catch something that was a misprint or you find the magic bullet and want to repeat it.
 
The top ring is tricky to measure as it is a tapered "keystone" ring. That is the outside is thicker than the inside of the ring. The taper is on both sides of the ring. Your feeler gauge isn't parallel to the piston top. I believe you make the edge of the ring even with the piston to measure it.

Military manual is in the reference section on here.

I wondered if there was different specs for the three or four 6.X diesels offered in 92-93? You know 6.2 NA, 6.5 NA and the HO 6.5TD that is alone for a coated piston top. And then is military a different spec for higher ECT in Hummers?

What about Navistar cast and GEP Optimizer redesign?

I already ran into valve size differences...
 
Will L. said:
Hink and I were speaking before the post. My Hummer manual has same spec as that from NVW.
Now, it makes sense because newer AM General aka Hummer is using what they had on record. But if the ine source to military is off, all of it would be off.

Hink has a GM 1993 manual that had different spec.
@Hink please post the picture of that here.

Can anyone please post any literature they have on it?

As pointed out by WarWagon, there have been other misprints.

Anyone have all data maybe?

I have always grabbed whatever book was at hand. I don’t remember tolerances- never try to on purpose- I always read the spec like 5 times while building.
Finding which is right is good not just for a few of us rebuilding right now, but everyone the builds afterwards.

Anyone that is running a recent build might want to open and correct before catastrophic failure occurs...
And on that note- always write and keep your actual specs as you do it for future. Maybe you catch something that was a misprint or you find the magic bullet and want to repeat it.
Click to expand...

Sure,
One is from a 1993 GMC service manual...

20190117_221341.jpg

Notice it has a spec for groove clearance even though it's a keystone ring that you don't measure for (do Hummers have a flat top ring?) and the 2nd ring groove clearance looks like it has a 0 missing. Probly should be .075-.100mm.

The other is from a 1993 Chevy unit repair manual (what's the difference, I don't know)...

20190123_183604.jpg
 
Went and looked at factory optimizer rings real fast, top ring is keystone. Wife called and had to run out the door before i got to second ring. She is driving so i can type... should have brought piston wnd feeler gauges. She wouldn’t mind an oily piston on the fj cruiser dash, right?

Also, wonder if
A. gm had different land clearances than gep.
B. Could specifications have changed when gep took over even if lands are same size?

Does anyone have specs for optimizers?
 
Will L. said:
Went and looked at factory optimizer rings real fast, top ring is keystone. Wife called and had to run out the door before i got to second ring. She is driving so i can type... should have brought piston wnd feeler gauges. She wouldn’t mind an oily piston on the fj cruiser dash, right?

Also, wonder if
A. gm had different land clearances than gep.
B. Could specifications have changed when gep took over even if lands are same size?

Does anyone have specs for optimizers?
Click to expand...

Shouldn't the military rebuild manual be for Optimizer?

And even more important to me than if there are differences is why?
 
6.2 Hummer engine, 1990, I have apart has the same Keystone top ring. If I bottom the top ring on the groove there is no clearance. First one I grabbed and the pistons fought me hard on the way out...

Military manuals have a date of publication so you would need one dated after Optimizer production.
 
I should have said- no clue what the original 95 engine had for rings. That engine is somebody’s new front bumper by now.

I have 2 manuals the one that is same as NVW’s is 1995 hummer with gm block. Let me double check my military manual, it is January 1996.
 
Yup. No other ring specs in the book. No missing pages, I literally looked at every page number.

Went to look at what came on the optimizers pistons second ring. They are torsional style, and I could NOT fit a 0.0015”/0.038mm feeler gauge in there- all 8 pistons. I have to Dig to see if I have one thinner, but clearly tighter than the 95 book specs. But there is carbon on the rings from running, so i would need to soak them to clean it for proper measurements 5 tenthhousandths is mighty small and could be the carbon blocking it.
 
Will L. said:
Yup. No other ring specs in the book. No missing pages, I literally looked at every page number.

Went to look at what came on the optimizers pistons second ring. They are torsional style, and I could NOT fit a 0.0015”/0.038mm feeler gauge in there- all 8 pistons. I have to Dig to see if I have one thinner, but clearly tighter than the 95 book specs. But there is carbon on the rings from running, so i would need to soak them to clean it for proper measurements 5 tenthhousandths is mighty small and could be the carbon blocking it.
Click to expand...

Wow, yeah, pretty tight.
Maybe just rub them on a smooth surface with sandpaper on it would be quicker/easier?
 
You must log in or register to reply here.
Back
Top