Piston ring gap

[406 Sonoma]

what kind of ring gap do you guys run on your motors. the rings on mine say a min. of .004 I gaped them at .030 this will be a n/a motor. thanks, Eddie.

[1fast10]

thats a loaded ? depends on bore size. n/a or nitrou, turbo or supercharged. depends on style and type of material in ring.

[wikd]

this might sound like a stupid question but... did you measure the gap with the ring inside of the bore??? .030 is an awful big gap for any motor... you will have issues with blow by and increased crank case pressure...

[1fast10]

i have .030 ring gap but thats a nitrous engine. i think .015 is a good starting point

[406 Sonoma]

no its not a nitrous engine and the bore is 4.155. I placed the ring in the bore and measured .030. its weisco plasma moly rings.I will measure the bore later to check the 4.155 is true.

[mytmouz]

Be sure the ring is square with the bore (I use an old piston) and measure the gap with the ring partially down the bore. .030 is a little large for a nuts only combo...

[onehookinsuv]

A n/a motor should be 0.15 to 0.18 make sure you have something to square the rings in the bore. 0.30 and up is about what I use for a nitrous motor. good luck

[406 Sonoma]

the rings came with the pistons, but I measured the bore at 4.145, and the piston at 4.120 everything is supposed to be .30 over so if anyone has come across this before please let me know.

[jameskirk1]

This is a real critical area, so I would call the piston and/or ring manufacturer for the dimensions you are supposed to have and where that dimension is measured. Depending on the metalurgy of the piston the sidewall clearance may or may not be correct, and the same goes for the rings and their reccomended gap setting. If the pistons are cam ground you will have to measure them at a certain place to get the right measurements.

Keep in mind that your parts might have been mis-shipped, mis-labeled, or mis-machined so check ALL of them against each other and ALL of the bores in the block as well.

[jdrags10]

Pistons seem a little loose. Most piston manufactures say between .005 and .007 clearance on forged pistons. And for the ring gap they usually have a formula to get the proper ring gap. Say a na combo total seal says .0045 times the bore. And the formula changes from top to second ring. My motor is gapped real loose with .035 top and .028 second. And it's for more than 400 shot of spray

[mytmouz]

the rings came with the pistons, but I measured the bore at 4.145, and the piston at 4.120 everything is supposed to be .30 over so if anyone has come across this before please let me know.

Pistons are too small for the bore, those measurements are for a .020 over bore on the block, and a 'small' standard bore on the pistons...

[406 Sonoma]

update I got a inside bore mic and the bore is .030 over, and got a bigger set of calipers and checked the part # and the pistons are 4.155 also so now I have to call weisco and ask them whats up with the .030 gap rings they sent.

[blackwidow]

To, if the pistons are hyper the top ring gap is larger than normal.