what rings for 86 5.0 ?

i had a problem with summit where they sent me the 5/64ths rings and they were too big. i had to get the 1.5mm and 4mm rings. dont know if this helps or not

it's a 4 inch bore correct? and your using 4 inch rings, not .020 over or anything right?
I know I had the same problem, sort of, took one of the pistons into the parts dept. with me to make sure they ordered the right ones before paying. make sure you have the ring compressor tight enough. Don't know if your using an engine stand, but it makes it alot easier when the block cylinders are facing straight up and down, those rings compressors---esp the cheap free loan a tool ones are known for popping off if the pistons not tapped down into the cylinder perfectly straight. If your using molly rings you made sure to clean the cylinders REALLY well right. There can be NO black on the white SMOOTH cloth your cleaning with. They will have a hard time seating otherwise. You also made sure to turn the top two rings 180 degrees opposite each other? Just a few things I thought I'd mention since you where there. Seeing as how you're rebuilding the thing your self you probably already knew that.

z2o_what said:

they were suposed to be 4" it said STd on every box i got

i took one of the pistons with me to make sure i got the right ones....but the rings that i got went on way too easy to be standard.

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Usually the taper is further down on the piston, However if 4 boxes says std, I'd be pretty confident they where packaged correctly. I would def check the pistons to make sure they haven't worn down over time. I wouldn't think that would cause an install problem though. What I do and it may work for you is after the rings have been installed on the piston and piston compressor secured to the piston, take a ball peen hammer and tap the center of the piston into the cylinder with the wood end of the hammer. If it starts to tilt straighten the piston before going any further, ensuring that all 360 degrees of the rings drap into the cylinder at once. As long as the compressor is up tight to the cylinder walls it should pop down after 2 or 3 trys.

I didn't even think to ask do you have a lip in the cylinders where the piston reached TDC? If the cylinder hasn't been ball honed or anything it may make it a little more difficult to install the rings.---Not for sure though never installed new rings without at least ball honing first. Also your connecting rod isn't banging against the crankshaft preventing the piston from dropping down, thus causing the piston to go down just far enough for the rings to pop out of the compressor? If all of these things are checked and turn out ok, I'm lost?????????