A little advice on ring gaps and assembly lube

[65dragster]

New to the forum, but have really enjoyed all of the experience, expertise, and collaboration from everyone. I have assembled maybe six engines, but now realize how little I actually know. I am doing a Chevy 350 (70’s vintage) for a street-strip deal in an early Nova. Ross forged flat top pistons using 1/16 top and second rings. What is a the right ring gap for moly faced rings. I don’t plan to use nitrous and the compression ratio will be 10:1 using a zero deck block. Also, what is a good oil or lube for pistons and cylinder watts? The motors may sit for 3-6 months before it is actually broken in and driven. I will appreciate all advice since I haven’t done an engine in 15 years. Thanks in advance!

[houser45]

Motor oil on the piston rings, cylinders, and piston skirts. 5/30, 10/40,15/40 whatever. Assembly lube on wrist pins, bearings. Emp #3 on rod bolts, pushrod ends, valve stems, camshaft break in lube on lifter faces and csm lobes, (whatever your cam grinder recommends)

[65dragster]

Thank you. Any recommendations for ring end gaps?

[Sparksalot]

Follow the ring manufacturers recommendation for your application. Fitting rings is one of the most tedious operations in building high performance engines. Your engine likely will do very well with rings purchased for your bore size without fitting and unless you're racing at the edge it will be wasted effort.

[mag2555]

you should be fine with rings that are pre- gapped if your block was bored and honed proper, but you should still take whatever time is needed to detail the rings at the gaps, all of the ring gaps especially the oil rail rings as many times they are the worst offenders!
Sharp gap edges( front , back , top and bottom ) need to rounded over with a soap stone or 320 grit wet or dry sandpaper glued to a nail file board.
With Moly face rings rounding over the edge that rides on the cylinder wall needs to be done by motions pushing in towards the pistion , as if you deburr with motions pulling out you stand a chance of chipping the Moly face off.

All of this work pays off with no scratches on your cylinder walls which in turn means far less friction and since all the rings rotate in use it means your ring land gaps will not ware open either, and also your not dumping fine grit into the motor .

The other very important thing is installing the compression rings themselves on the Pistons , if you have little experience in doing this then spend the bucks for a ring installing tool because if you put a twist into a ring that does not come out ( even a very very small one!) you can kiss good sealing in the cylinder goodbye!

[65dragster]

Excellent, very helpful, and detailed replies. I truly appreciate the guidance. This forum is an amazing tool with some highly skilled contributors!

[hondo383]

I've never heard of a pre gapped ring?
.005 gap per inch of bore top ring
.0055 gap per inch of bore 2nd ring
For basic NA hot rod..
Maybe a little less if below 400 hp
Agree on deburing well and check ALL the oil rails sometimes they mix in some wrong ones lol

[rebelrouser]

Just don't use synthetic oil for an assembly lube on the rings, it works too good. Use a mineral based oil. I have found ring sets for stock engines too tight and too loose several times. I always check gaps. I use the standard .004 per inch of bore for stock engines, and the ring and piston manufacture specs for performance engines. If I don't have a spec for max gap I double the number arrived at by the .004 and use it as a max limit. If using used piston the ring side gap in the lands is critical as well. worn lands will make them use a lot of oil.

[tresi]

The vast majority of rings are pre gapped but still check them.

[engineguyBill]

All of the information presented in previous posts is viable. In summary:

Piston ring gap is typically recommended at .0045" per inch of bore for the top ring (.018" for 4.000" bore) and .0055" per inch of bore for the second rings. This formula holds true for all NA applications, regardless of ring material. Be sure to use a ring squaring tool (or top of a flat-top piston) to place the ring into the cylinder for gap check.

Use good quality mineral-based motor oil to lubricate the cylinders, rings/ring grooves, piston skirts. Apply oil to the rings and grooves with a squirt can, do not dunk the pistons/rings into a bucket of oil. Engine assembly lube throughout the engine and moly lube on cam lobes, lifter faces (flat-face lifters), valve tips, rocker arm contact areas. Do not prime the engine oil system until the engine has been installed in the vehicle and is ready to start and begin the break-in process.

[65dragster]

Thanks again for all the great information. I started in on the short block today. It is nice to approach it with confidence knowing the feedback on this forum will always provide quality answers.

[rebelrouser]

The best squaring tool is a roll of cheap making tape, just peel off the tape until it just fits the cylinder. Push the rings in until roll of tape is flush with the deck. I keep several rolls from dollar general in the shop.

[65dragster]

Thankfully I have a ring squaring tool, but I love the idea of a tape roll! I am checking the top and second rings on various u cylinders to try to get the gaps the same without a bunch of grinding. I will definitely pay attention to the rings ends. I am glad for those who mentioned deburring and verifying oil ring consistency. Thanks again for helpful ideas!

[tenxal]

Lots of good advice for you, here. EngineguyBill's method is virtually identical to what I do.

I'll add a couple things: Use a good break in oil like the Driven BR30 5w30, Brad Penn, or Lucas. Preoil the engine on the engine stand with the intake off. Rotate the crank 90 degrees every once in a while to make sure all the rockers have oil to them.

Sounds like a nice build.

[steve316]

.018 top ring; .025 second ring. Use a good assembly lube on bearings and wd 40 on rings. Any questions on ring lube go to total seal web sight.