You should always check the ring gap even if the rings were supplied with the pistons. The gap should be checked with the rings in the cylinder that they are going in. If you plan to use heavy doses or nitrous or heavy boost, the top ring gap needs to be larger because they will expand more due to the extra heat.

 

z28 pete, did that, rings cked. outed . what is the best guess on the finile gap. all cyls. run + or - .02 .
would .35 ring gap do it
ROG

 

I disagree with the theory of the top gap being bigger!!! I set my rings at .028 top an .030 bottom. You are right about the top getting heat an expanding more but the second ring needs to be larger so that any cylinder pressure tht gets past the top won't get trapped between them, it will lift the top ring land an ruin the piston an possibly hit the head, been there an done that.Evan if ya just jet it too rich, unburned fuel can get past the top ring an build pressure between them, ya don't want that, let it go past the 2nd an into the crankcase. Ya gotta run a good "crankcase evacuation system " or a vacume pump. I run a simple Moroso Evac kit from my headers to my valve covers an they work great on my small block an my BBC, 50.00 bucks is all they cost an they pull lots of vacume. Now for the kicker, My motors are for heavy nitrous use, you can get by with a slightlytighter ring gap on a street motor that will not see much nitrous, under 180hp.Just make sure the second ring is 1-2 thousands bigger than the top.

 

da z28 thanks all the info. I get is good. i'm sorting all this out. hoping to to find the right combo.
I idea is for a go fast road machine. back in the day 60's70's we were building iron just for the strip or light to light. now it's more about Big Horse Power road killers. And I kind of like that .

 

I know what ya mean, I started inthe early 70s street racing too. Things have changed alot but if your willing to learn you'll still pull some wins against these youngins. I forgot to mention that hyperutectic pistons are stronger than cast but much more prone to shattering or breaking apart under detonation.Retard timing about 1.5-2 degrees for every 50hp of nitrous ya spray.Watch your timing an tune up-read plugs for detonation, lots of guys spray em hard an they seem to last but a forged is better for nitrous.

 

da Z28--I looked into the hyper. pistons only after I started thinking about all the exter work involved in fordged pistons as i see read it the these hyper. piston do expand nearly as much as fordged. so that was one reason for my picking the hyper.s as for ring gapping back in the day We all had sore fingers fileing rings -on ring gapping machines for sale back then?. the more info . I got on the hypers , I like what I saw .since I'l not building an all out streetracer Iway of thinking is thehypers. were the best bet??? it's only now after looking into nitrous that any questins started to pop up in my brain pan??? keep the info. coming been a long time since I was a hard core night rided

 

I think your absolutly right, detonation should be watched for real close with hyperutectics, it should with any piston. As long as your careful with timing an a safe octane fuel they should work fine. A friend of mine sprayed 250 to his lots of times, an I had a 350 targetmaster(260hp) with stock cast pistons an hit it with a375hp shot.all summer long. I still have the shortblock on a engine stand, it is in fine shape an only needs re-ringed an bearings from a summer of racing, never hurt it. If ya just spray it now an then it'll last a long time.