Hey guys,
I have a chevy 350 (believe its made in 93, dont know what it came out of) and im having a problem with the piston rings. The compression rings have correct end gap, but the oil rings are not allowing the piston to go down the bore. Once the oil rings enter the bore past the ring compressor it becomes very tight. I am reusing the stock pistons with some cheapo hastings rings. Its a daily driver motor im building for my caprice...........now back to my story, i have been told that there are 2 types of factory pistons for these motors. one has a deep groove oil ring lands and the other shallow. Deep groove are .200" deep and shallow are .165" deep. What the hell is going on?:mad:

Rock,
The newer pistons use a very shallow oil ring. That is the main problem. Also, depending on the exact piston, they have gone to metric rings which are very close to the old ones, but not the same. If you give me the piston number off the inside of the piston, I can probably figure out which rings you need, but might not be able to do it till Monday. Your old Hastings 139 set will definitely not work. The best thing to do is measure the ring grooves to see how wide they are. They changed several times over the course of a few years, so you have to be sure to get the right rings. And ... be ready for sticker shock compared to the $20 Hastings set :(

heres the number on the inside of the skirt #10128249, under that number is these numbers 6106.........another question, can i use the stock '91 305 flywheel for my '93 350?
thanks for the help bill:beers:

rock,
The flywheel should work fine. I might have a piston crossover catalog out in the garage, will look in the AM. If not, definitely can find out Monday AM.

I have some more info, i went to hastings master catalog and found two sets that may be compatible with my motor, one being the aforementioned metric ring lands, the other with standard ring lands but shallow grooves. If I follow there page correctly, the standard ring set has both top and bottom compression rings the same size (5/64"), and the metric set is 2.0mm top, and 1.5mm bottom. I threw away my old rings (i know, it was stupid, i usually hang onto everything until the job is done)........except i did keep one ring for cleaning the lands. I measured that ring and it came out to .0781, which is 5/64". This leads me to believe I need standard rings with shallow groove oil rings.
heres the catalog
http://www.hastingsmfg.com/Catalog/catintr.asp

80, ( Name ?? )

I was just looking at the same thing. Try one of your new rings in the top groove, if it fits, then you are probably right, you need the 5615, or 2M5615 (Moly) ring set. All of the metric rings are narrower than the 139 or 2M139's which is what you probably have now.

The rings i have fit. The end gap is good with the compression rings I have. The oil rings are whats holding up my project which i wanted to be done tommorow, but that will have to wait.
My name is Don but I think "Rock" sounds more badass, so just call me that:D
Did I mention this site kicks ass?

^^^WHOOOPS!


The same thing has just happened to me. I purchased the .200 deep groove oil rings. Did the .165 Shallow ones fix your problem??

Did you notice the date on this thread?

Yes I did. But this was the only existing thread i could find on the exact same issue I had, Word for word. So I figured I would give it a shot if someone still had some good info.