KB piston Ring advice

[EP87]

Hi getting ready to order piston rings for my son's new 360 and need as little help with the rings.

Its a 360 .030 over with KB107 pistons KB say's that for a street application the top ring needs a end gap of a little over .026 (4.030 x .0065 = .026195)
and for drag race a little over .032 (4.030 x .0080 =.03224)

since the car will see very limited strip use I'll go with .026

My question is will I need to go with file to fit ring, or can I buy something off the shelf that will work and give me this much gap? I've never filed rings before but with the proper tool it seams pretty easy.

Any advice on brand or type would be great also. (moly, cast, sealed power,etc.)
Richard

 

[C130 Chief]

Go file fit Moly, since you'll be filing rings anyhow (speed pro are as good as any, and the same as most). Also, I'd sure think long and hard about going more like .030. KB pistons place the top ring pretty high so it runs hotter (the running gap will be small due to expansion). Go all the way to .032 if you even think you might use a nitrous shot. If those ring gaps close up tight, you will start breaking parts in a hurry.

 

[EP87]

Go file fit Moly, since you'll be filing rings anyhow (speed pro are as good as any, and the same as most). Also, I'd sure think long and hard about going more like .030. KB pistons place the top ring pretty high so it runs hotter (the running gap will be small due to expansion). Go all the way to .032 if you even think you might use a nitrous shot. If those ring gaps close up tight, you will start breaking parts in a hurry.

Thanks I think your right better safe then sorry, and if we do decide to go with nitrous down the road we'll be set.
Richard

 

[EP87]

One more part to this question I'm looking at the sealed power file to fit rings at summit and all the sizes seam to be .005 larger then the ones I'm looking for example I need 4.030 and I only see 4.035 Is that the correct size?
are they oversized for a tighter tolerance, and if so can I buy regular non-file
to fit rings and file them since I'm looking for a bigger gap?
Richard

 

[dgc333]

When I did my 360 with KB107 pistons I just purchased off the shelf Speed Pro moly rings and filed them to the 0.026" gap. I would think that the only you would get with file fit rings is the need for more filing to get to the desired gap.

As I recall the off the shelf Speed Pros were about 0.018" before I filed them.

 

[EP87]

When I did my 360 with KB107 pistons I just purchased off the shelf Speed Pro moly rings and filed them to the 0.026" gap. I would think that the only you would get with file fit rings is the need for more filing to get to the desired gap.

As I recall the off the shelf Speed Pros were about 0.018" before I filed them.

Thanks- that exactly the info I needed. The good thing is the regular gap speed pros seam a little cheaper then the file to fits. :thumbup:

 

[lead69]

I would also just use the speed pro molys,Ive used several sets in different makes of engines and filed them-less filing to do.Out of the box I needed to open the top gap slightly even on cast/forged pistons to get the ring gap totally correct.