Using first oversize rings in a std bore

[John OBrien]

Hi there guys - just a newby - I'm helping my son with a '78 that has had low compression on the right cylinder. We tested valve tappet clearances etc, changed plugs. Short of it we took out the engine and pulled it apart - alot of carbon around the valves. Re ground the valves and cleaned the heads. Slight bit of scoring on the cylinder - front cam chain guide disintegrating so guessing it got churned up? - not sure.

Anyway we got new seals etc / rings from Geoff's XS - great guy.
We got a first oversize set of rings with a standard bore.

Question - we filed the rings to give the proper clearance (.2 - .4 mm) and they are fitted. Engine is not running yet. Will they be ok? I am concerned with the slight eccentric nature of the new rings vs the bore or is this so small it doesn't matter?

Thanks! Any suggestions comments welcome

 

[xjwmx]

I am concerned with the slight eccentric nature of the new rings vs the bore or is this so small it doesn't matter?

Thanks! Any suggestions comments welcome

I pondered this once myself. I think...that when it's in place there won't be any eccentricity, since the ring has equal strength all the way around. I found my bore to be within tolerance for std rings though, gaps were good, with 60,000 mi.

 

[Jim]

Question - we filed the rings to give the proper clearance (.2 - .4 mm) and they are fitted. Engine is not running yet. Will they be ok? I am concerned with the slight eccentric nature of the new rings vs the bore or is this so small it doesn't matter?

Using first over rings to file down your own end gap is a very common hotrodder trick. You're a hotrodder now.... you jus' dint' know it
Yes.... will work just fine.

 

[5twins]

I've done this on several motors over the years and never had any issues. The reason is to get nice tight ring end gaps down near the minimum spec. Many times, on a used bore with some wear, new stock rings won't have a very tight gap. Sometimes it will barely be in spec, sometimes it will be above the spec. Now granted, this is the new spec, they may fall below the max wear limit, and usually do. It's just that if I'm going to go through all the trouble of replacing the rings, I'd like to be able to get nice tight end gaps down near or at the minimum spec. I even have a "special tool" for filing them .....

This is a dedicated ring end gap filing tool and as far as I know, that's all it's made for.

 

[racerdave]

I've done this on several motors over the years and never had any issues. The reason is to get nice tight ring end gaps down near the minimum spec. Many times, on a used bore with some wear, new stock rings won't have a very tight gap. Sometimes it will barely be in spec, sometimes it will be above the spec. Now granted, this is the new spec, they may fall below the max wear limit, and usually do. It's just that if I'm going to go through all the trouble of replacing the rings, I'd like to be able to get nice tight end gaps down near or at the minimum spec. I even have a "special tool" for filing them .....

This is a dedicated ring end gap filing tool and as far as I know, that's all it's made for.

Had a similar one years ago. Also works good for making
notchs in things. No idea where that got loaned out to and never returned now.

 

[John OBrien]

This is excellent feedback - thanks to all! We will push ahead with the assembly and hopefuly post pics of a working engine. Cheers and thanks again.

 

[FLEA]

did the same yrs ago , put thousands of kls on the motor and was still going strong when sold

 

[John OBrien]

I've done this on several motors over the years and never had any issues. The reason is to get nice tight ring end gaps down near the minimum spec. Many times, on a used bore with some wear, new stock rings won't have a very tight gap. Sometimes it will barely be in spec, sometimes it will be above the spec. Now granted, this is the new spec, they may fall below the max wear limit, and usually do. It's just that if I'm going to go through all the trouble of replacing the rings, I'd like to be able to get nice tight end gaps down near or at the minimum spec. I even have a "special tool" for filing them .....

This is a dedicated ring end gap filing tool and as far as I know, that's all it's made for.

This is a cool machine - you would need to be doing a few motors to justify it - then again. We just used a small flat file and wet and dry.