[baddbob71]

Just got the roatating assembly and block for my son's 331 back from the machine shop. The only things left before final assembly are to gap the rings and wash everything. I found the Speed Pro rings I bought have a gap of .021, I was hoping for .016 on the top. The last engine I built I used regular Hastings moly and had to file to get .016. Should we run it with the wide gaps or just buy file to fit rings? Should I close it down to .014 or less? A Smokey Unick book I have recomends .003 per inch of bore and an old Chevrolet service manual I have says .013 for a 327. Or does anyone know if the Hastings regular ring sets are still being made on the tight side requiring file fit?

Also numerous manuals including one I have recomend different ring end gap placement on the piston. Whats the proper end gap placement in relation to the piston? In the past I've always put compression ring end gaps parallel with the wristpin 180 degrees from each other. I've also been told it doesn't matter since the rings rotate continuously Mechanics have told me they've torn down oil burners to find all the ring gaps lined up So what's the scoop here? Do the rings rotate? Are they supposed to rotate? I could throw this thing together and I'm sure it'll run OK but if it's going to be down on power and popping breathers from to much blowby I'd rather do it right. Anybody?

 

[sugarwolfpimp69]

Take the rings back at get the speed pro file fit rings, makes life much better. I run my file fits rins at .015 at .021 you will probbly get some blow by also check the cylinder size to make sure the machine shop did the job right. And i have always placed the rings 180 of each other and make sure you do not line the gaps up..The rings are not suspost to move around on the pistons.

 

[Pat Kelley]

My understanding is the rings do rotate around the piston.

 

[Wolfplace]

Originally posted by XXX:
Take the rings back at get the speed pro file fit rings, makes life much better. I run my file fits rins at .015 at .021 you will probbly get some blow by also check the cylinder size to make sure the machine shop did the job right. And i have always placed the rings 180 of each other and make sure you do not line the gaps up..The rings are not suspost to move around on the pistons.

The rings do rotate in the grooves. You will almost never find them where you put them when you freshen an engine.
Also just for info we have found the "Total Seal" second ring pack with the rail & ring lined up in at least one cylinder in damn near every engine we have freshened that had them.

Trust me,,,they move in the grooves

 

[Unclepennybags]

Originally posted by baddbob71:
Should we run it with the wide gaps or just buy file to fit rings? Should I close it down to .014 or less? A Smokey Unick book I have recomends .003 per inch of bore and an old Chevrolet service manual I have says .013 for a 327.

badbod71,

Personally, I really believe that the benefit from doing it yourself is that you can file fit the rings. Go with .016" for the top ring. Seems to me that with an out of the box ring, you are leaving power on the table that you could be using. A reasonable guess would be ~10 h.p. difference between the generic out of the box fit, and a file fit.

I was taught to arrange the rings like the diagram in the shop manual. It's never failed me.

Mike

 

[baddbob71]

I guess I'll see if I can return these and get some file fit. This engine is balanced, decked, ported, etc. with a lot of good parts so I guess there's no sense in shortcutting it in the end. I think I'm going to set them up tight with .014 or .013 gap, I don't forsee this thing running hot with a 4 core radiator and the air temps we see up here. If I remember correctly one of the mags did a ring gap test including total seal and the engine made more power with tightening the gaps untill they butted. the last engine I built I opened up the second ring gap .002 more than the top and wish I hadn't-oil contamination seems to be more than average. And the speed pro tests I've seen only show power increases above 7000rpms with the wider second gap.

 

[headerfire]

Yep,,piston rings will rotate when the engine is running.
Nothing like a flat tappet lifter,but they do move around.

 

[Pat Kelley]

Don't tighten them up. The .004 X the bore is the minimum. Don't go by old books, materials may have changed. Use the mfg's recommendation. They spend mucho bucks on research and know what they are talking about. Yes, they may be a bit conservative but they want your engine to survive.