Question for engine rebuilders

C

chambies

Senior Member
Got my block back from getting bored for .060 new rings and pistons. I borrowed a piston ring grinder to set my own gaps. From what I read I am shooting for .016-.018 for this size bore. On my initial check my gap is .035???
Seems really large without taking any material off. These are quality rings. I am making sure to seat them square in the bore. What am I doing wrong or is my build going to suffer from this being too large???
1935 “A” diamond block
Counterbalanced crank with lightened flywheel
Thomas head 6:1, dual 97’s
Thanks for help!
 
You are not doing anything incorrectly. In a general application for a low-performance engine, that is what you are going to find. If you purchase a quality forged piston brand using low-drag, gapless rings, the story is different. At the compression ratio and RPM that you are using in this application, there performance advantage is minimal at best.
 
chambies said:
Got my block back from getting bored for .060 new rings and pistons. I borrowed a piston ring grinder to set my own gaps. From what I read I am shooting for .016-.018 for this size bore. On my initial check my gap is .035???
Seems really large without taking any material off. These are quality rings. I am making sure to seat them square in the bore. What am I doing wrong or is my build going to suffer from this being too large???
1935 “A” diamond block
Counterbalanced crank with lightened flywheel
Thomas head 6:1, dual 97’s
Thanks for help!
Click to expand...


sounds like you might have the wrong rings
how much clearance do you have on your pistons

Terry
 
One of the rebuilders uses custom pistons sized right on the target bore diameter. The .003" clearance is then machined into the block making ring gap too wide. I bought some rings by spec, fitted them to my bores, and returned his rings.
 
I will take a little time today to take measurements of all bores and pistons just to check and see. Rings are good quality from Hastings.
 
My thoughts are Modified.

I sometimes write a letter to the editor of our local newspaper. By the response of readers my point of view is well received and agreed with. I am always careful to avoid personal attacks, abuse, bad manners and rudeness. Despite this the newspaper frequently modify and omit data and won't print anything controversial. So I wrote the letter that follows.

Letter to the Editor 25/09/18.
It is pleasing one has the forum to voice one's opinion, thoughts and other things. The forum of course being the "letters to the editor" in your newspaper.
However it seems every letter I write is modified or has sentences removed. These are no longer my letters but now editorials and I would be pleased if when you modify your would head them editorials.
Thankyou in anticipation for publishing my letter.
gary mexted.

the response was fast and precise. "no, we won't publish your letter".
Isn't it disappointing to have one's opinion modified.
Would you be pleased if yours was?


The date above. Unlike Americans we write the date in the following format. day, month, year.
 
I don't think that .035" ring gap will have any effect whatsoever. Consider: At ambient temperature (cold engine), piston diameter at the ring lands is about .030" smaller than skirt diameter, so we have .015" clearance above that .035" gap. That gives us a .000525 sq. in. opening for compression to escape. Assuming a cranking speed of 120 RPM, that gives about 1/2 second for the compression and power strokes. Just how much compression can be lost through that tiny opening in that brief time? Very, very little! With the engine running, the compression and power strokes occur in milliseconds.
With the engine at operating temperature, the top of the piston has expanded, as have the rings so our little opening is even smaller.
Which leads to a common but baseless myth that falsely claims an engine will not start or run if all the ring gaps are lined up! There is a relatively large volume of 'empty space' between each ring as well as between the piston and cylinder wall. So any compression/combustion pressure escaping through the top ring gap will simply flow around the piston to wherever the second ring gap is, and immediately escape through that gap. In addition, rings rotate in their grooves, so they are probably are all lined up at some point in your engine's life!
 
woofa.express said:
My thoughts are Modified.

I sometimes write a letter to the editor of our local newspaper. By the response of readers my point of view is well received and agreed with. I am always careful to avoid personal attacks, abuse, bad manners and rudeness. Despite this the newspaper frequently modify and omit data and won't print anything controversial. So I wrote the letter that follows.

Letter to the Editor 25/09/18.
It is pleasing one has the forum to voice one's opinion, thoughts and other things. The forum of course being the "letters to the editor" in your newspaper.
However it seems every letter I write is modified or has sentences removed. These are no longer my letters but now editorials and I would be pleased if when you modify your would head them editorials.
Thankyou in anticipation for publishing my letter.
gary mexted.

the response was fast and precise. "no, we won't publish your letter".
Isn't it disappointing to have one's opinion modified.
Would you be pleased if yours was?


The date above. Unlike Americans we write the date in the following format. day, month, year.
Click to expand...


Gary, since you in effect are writing editorials or op/ed pieces, demand that they pay you!
 
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