Okay folks, It's been awhile since I had to do anything with piston rings. I need to replace the ones on my Chevelle, and I don't remember how to measure them to determine what size I need. The Pistons are Pro-Comp .030, and the piston bore is at least 4.11". Any help is appreciated.



Spoileddaddy

S'daddy, 4.110 bore??? What engine are you dealing with? Anyway, to order rings you will need to know the actual bore diameter of the cylinders, then you will need to measure the width of each groove in the piston. The most common widths are 5/64" top, 5/64" second and 3/16" oil OR 1/16" top, 1/16" second and 3/16" oil.

The engine is a GM small block 400, built between '73-'76. I'm going to re-measure the piston bore when I get a chance, but I'm pretty sure the measurement is somewhere around 4.115" (it's also been awhile since I used a Micrometer)........



Spoileddaddy

sd,
Standard bore size for a 400 is 4.125" The piston manufacturer should be able to tell you what size the actual rings are. I think the Pro-Comps are Wiseco ? If so, the rings are probably 1/16 1/1/6 3/16 but you really need to measure the pistons to be sure.

Thanks guys, I'll have to wait 'till this weekend before I can re-measure those piston bores, and pistons. I wrote the numbers down, but I can't find where I put the paper at.........Although on second thought, that 4.125" sounds very familiar (been working too many hours.......) I'll let ya' know!


spoileddaddy

I re-measured, and the size was 4.125". I replaced the rings, and now i'm told the Valve guides could be the cause of the previous oil burning? Is there any way to check the heads without taking the valves out to see if there is a problem with the guides? I don't have a spring compressor, that's why I ask.........



spoileddaddy