[SEL] Cylinder/piston questions

[Jim and Diane]

Hi Mike,

How about measuring the gap between the side of the ring and the groove. 
This ought to be pretty tight, .001 or maybe a tad more.  Rings that are 
loose in the groove will not hold compression at all well.  A good fit here 
is lot more important than the out of round that you have.

Jim

Jim and Diane Kirkes
Hemet, CA
jd.kirkes at verizon.net
----- Original Message ----- 
From: "Michael Tucker" <mtucker at uky.edu>
To: "The SEL email discussion list" <sel at lists.stationary-engine.com>
Sent: Sunday, May 22, 2005 5:49 PM
Subject: [SEL] Cylinder/piston questions


> Howdy all,
>
> I was able to start evaluating the mechanical status of my new toy today. 
> It's a 1907 (serial number R1434E) 4 hp, screen cooled, hit-n-miss IHC 
> Famous.  Although the rings were essentially dry, when pulling it through 
> compression it seemed to be loosing a lot of compression past the piston 
> at top dead center.  So, with the help of my machinist neighbors tools I 
> took some measurements of the piston and cylinder.  The cylinder is in 
> great condition with no hint of a ring ridge.  Up at the head end of the 
> cylinder the horizontal diameter is 4.8025" and the vertical diameter is 
> 4.8060".  At the flywheel end of the cylinder the horizontal diameter is 
> 4.8010" and the vertical diameter is 4.8035".  So, there is a tiny taper 
> and the cylinder at top dead center is only 3.5 thousandths out of round. 
> I think that I should be VERY happy with those measurements.  The piston 
> is what I'm a little worried about.  Although it is absolutely round up by 
> the rings and at the end of the skirt, between the first and second ring 
> the diameter is 4.780" and at the end of the skirt, it's 4.794".  So at 
> the top of the piston, that gives me a vertical difference in the diameter 
> of the piston and cylinder of 26 thousandths and a horizontal difference 
> of 22.5 thousandths.  In a perfect world, what should the difference in 
> piston diameter and cylinder diameter be?  Although the rings look to be 
> in pretty good shape, do you think that they could be the reason for the 
> blowby?
>
> Thanks for the help,
> Mike
> -- 
> ____________________
> Michael Tucker
> Midway, Kentucky, USA
> mtucker at uky.edu
> ____________________
> _______________________________________________
> SEL mailing list
> SEL at lists.stationary-engine.com
> http://www.stationary-engine.com/mailman/listinfo/sel
>