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Engine builders help! piston ring placement

Posted By: Scouttoo

Engine builders help! piston ring placement - 02/21/18 05:40 PM

Building my 440 and since it's been awhile since I've put an engine together and I've been searching about where to clock piston rings without any luck. I looked in my piston ring instructions and there isn't any info there either. From what I remember you don't want ring gap on the thrust side of the piston but I can't remember for certain. If anyone has a diagram or can lead me in the right direction I would appreciate it! Thanks!
Posted By: feets

Re: Engine builders help! piston ring placement - 02/21/18 05:45 PM

The rings will likely move around on their own while the engine is running.

The biggest thing is to install the first and second rings with the gaps at least 90 degrees apart.
Posted By: Lee446

Re: Engine builders help! piston ring placement - 02/21/18 05:54 PM

Second ring gap centered over left side pin, top ring centered over right side pin. Easy to remember. Or vice-versa, whatever you like.
Posted By: dvw

Re: Engine builders help! piston ring placement - 02/21/18 06:09 PM

The main thing is to make sure the oil ring gaps are away from the expander gap. Install the expander, then the upper oil ring it the gap aprox 120 degrees away. This will hold the expander in place. Make sure the expander ends stay butted and do no over lap. Now spiral the lower oil ring over the assy. Make sure you know which is the top and which is the 2nd ring. Make sure you know which side is up. A little oil in each ring groove and skirts. WD 40 on the walls and put them in. I set the top gaps 180 apart. But they'll move while running anyway.
Doug
Posted By: Scouttoo

Re: Engine builders help! piston ring placement - 02/21/18 06:11 PM

Thanks for the responses!

Yesterday I had to deal with a tight cam bearing.....
Posted By: 451Mopar

Re: Engine builders help! piston ring placement - 02/21/18 08:07 PM

Originally Posted By Scouttoo
Thanks for the responses!

Yesterday I had to deal with a tight cam bearing.....


That's pretty common on a big block.

For the oil ring, I do like the Factory Service Manual shows. See attachment.

The top rings I put the gaps in line with the piston pin, but opposing sides for top and bottom.

Attached picture rings.jpg
Posted By: Cab_Burge

Re: Engine builders help! piston ring placement - 02/21/18 08:14 PM

I've stagger the rings like the instruction say and then had a bunch of motors dyno tested and took some of the motors apart to inspect them, as already said the rings move around a lot shruggy
I had one motor that the gaps had align so they where all in the same exact spot on three pistons, no oil in the combustion chambers though confused work
Back in 1966 when Chevy started making the 396 SS Chevelles some of them had bad oil consumption problems, the word was that the UAW members at the motor factory had intentionally aligned all the ring gaps in a lot of those motors just before the strike that year, who knows if that was another myth or fact shruggy
Welcome to the world of tight Mopar cam bearings whistling grin
I bought a bearing scraper just for that reason wrench runaway shruggy
Posted By: 451Mopar

Re: Engine builders help! piston ring placement - 02/22/18 07:30 AM

The cam bearing thing reminds me. Make sure they fit the cam before installing them. Had a 400 engine where one bearing was really tight, took it out of the engine and it would not fit over the cam even before being pressed into the block? That was a King cam bearing set which I have never used before? Not sure if it was just bad luck or not, but I normally use the DuraBond PDP-17 cam bearings. I never tried the coated bearings, sort of an expensive waste it you have the scrape the bearings to fit?
Posted By: Scouttoo

Re: Engine builders help! piston ring placement - 02/22/18 04:29 PM

I had to scrape the bearings to fit. Number 4 bearing was the one that was giving all the grief. From the research I did this is common and although it felt weird to scrape material from new bearings it seems like accepted practice.

Thanks again for all the help. That's why I love this board!
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