Ring gap?

almareck

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A little back ground. Back in 2004 re-build my 76' 500. bored 0.030 over new pistons, new rings, the works. The motor sat for 10 years. I drove it for a summer and I was looking for a little more power so long story short, this winter I took the motor back apart. I never checked the ring gap when I first assembled the motor so I decide to check it now. With the feeler gauge it measured ~0.027" - 0.028" I have seen in several places that the recommended gap is 0.018" - 0.020" So it seems I am about 0.010" over the recommended gap. I check the bore and I am right on 4.330" So here are my questions.

Is 0.028 too much ring gap? I assume the answer is yes.

Does anyone make file-to-fit rings? If not, is it a good idea a buy a 0.060" set of rings and file to fit?

If no one make file-to-fit, where can I get quality piston rings that will give me the correct gap? Do you recommend a certain brand?

Alex
 

El Diablo

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What vehicle(s) do you drive?
1959 Cadillac Sedan deVille
Ring gap is going to vary depending on a few factors.
Can you give us some details on your engine combination?
 

almareck

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El Diablo that for the reply. Below is some more detail.

76' 500 block bored 0.030" over
500 crank turn 0.020 under on the mains and the connecting rod journals
stock connecting rods
0.030" pistons with 8 cc dish
CHP #10-EZ cam (now that I have the heads off might have the valve guide shortened so I can run the normal CHP #10 with the larger lift)
Stock replacement hydraulic lifters

Stock push rods
120cc heads (I ported)
Stock valves
Stock Rocker arms
CHP valve springs
Edlebrock Intake
FITech go EFI throttle body injection system (the motor is apart so I haven't bought it yet. I plan to break in the cam with the q-jet I have)
Stock exhaust manifolds

The motor is going into a 87' Suburban 4x4 for mostly street but some off-road use.

I am not planning to run any boost or nitrous.

I am wonder what kind of ring gap other people are running. I was running a PCV and there is a lot of oily soot inside the motor so I am thinking I was getting a lot of blow by.

Alex
 

El Diablo

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1959 Cadillac Sedan deVille
For a street & daily driver type engine on pump gasoline, I use the formula of 0.004" / 4" of bore. So with your 4.330" cylinder bore and assuming that everything is mechanically sound, you would be around 0.018" ring gap roughly. Of course if you are going to put more heat into the chamber, then you will want to open up the gap a bit more. Also note that on dished KB pistons, you may want to run a bit more gap as well. Some guys have had the rings butt up and pop the tops of the pistons off .
 

pila78

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I used the gap recommended by KB on their pistons..flat tops. Don't have the spec handy, but it was sure more than .018"... I'll have to look in the file...
 

DeVille68

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68 Cadillac DeVille Convertible
I got my piston rings from Hastings. Since I want to file my own rings to achieve optimum ring cap I ordered slightly larger rings for a Chrysler 400 engine
Part Number: 2M676 for a bore of 4.342’’
I have gaped the rings: first ring: 0.016’’ and second: 0.014’’

Factory cadillac shop manual mentions: 0.013'' to 0.025''
Hasting over the phone told me: 0.014'' to 0.026''
Egge (piston) over the phone told me: 0.018''
Hot rod article: 0.014'' to 0.018''
My Engine rebuilder: 0.016''

Hope my data helps you!
No problem in filing the rings, however take your time. I took me all Saturday.

Best regards,
Nicolas
 

almareck

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Thanks Nicolas. It is nice to know I can file the rings to fit. I plan to target .018" or .020" of gap.

Did Hastings stop selling rings? They only place I found them was ebay. Which I don't trust. RockAuto has Mahle/Clevite or Seal Power.

Alex
 

DeVille68

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Hi Alex,

well, yeah, that information was wrong. I got my rings from a parts supplier in the Netherlands. I would go to the hastings website and call their support number ask them where a nearby dealer is. Hastings just recently bought another ring manufacturer. I think they are doing quite well.
The ring design on the "wrong" Chrysler ones were identical to those used for the Caddy engine. I got the moly coated rings. Get yourself a good ring filer. I borrowed a filer from my engine rebuilder. There is a limit on how far you can file the rings. Ask hasting too if you have them on the phone.

Best regards,
Nicolas
 
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