Extra clearance?

[sc racing]

Im starting to build the new engine its not going to a "nitrous" engine but I am going to put a plate kit on it 250hp max. I will stay with the smaller jets until its all tuned .Ive seen in some of our motors scored pin bores and ring lands that are separated these werent " nitrous" motors and I know they didnt have extra clearance.How much clearance should I run on the wrist pins and if I dont have a nitrous piston will the upper ring lands lift?
Engine: basic 406" Scat or Eagle type bottom end H beam rods 13 or 14:1 compression not sure what heads or cam yet single carb with Super Victor intake etc etc etc .Thanks Steve

[sc racing]

Nobody has nitrous????

[John_Heard]

We didn't use any extra clearance on the wrist pins in my old 505, but they were ceramic coated tops and the moly skirt coating on them. We used if I remember right .0065 cyl wall clearance and that seemed to work pretty good. I don't know that you would have to worry too much about lifting the ring lands and all that for a 250 shot unless they are super light pistons and weak in some areas. In mine we just used plain jane SRP pistons, not the nitrous versions. Moly rings would be fine too at that shot level or below..

[sunsation540]

keep the pins at .0008-0.0013 when you add to much clerance it won't hold oil allows it to be pushed over to one side bottom or top the reason most and i say most have problems with wrist pins/ flat tapet cams and many other ills is rod side clarance and type of oil. the oil thing is talked about in other areas of this site as i have seen it so look that up.. the side clerance on the rod throws oil on the cylinders that the rings pick up and the oil ring pushes in to the bottom of the wrist pin bore make sure the side clerance is sufficent for the rpm the mtr will see. the only oil the pin sees is slung off the rod! loose is wrong. and at some power levels the piston dome tin cans causing binding on the pins we find the pin struts to the botom of the piston cracked in the high hp mtrs after 150-200 runs not to much on the sbc look at the bottom of a nascar piston then look at the bottom of a drag piston big diff. the nitrous pistons offer thicker crowns 0.025 wont save a mtr from a bad tune-up dimond/ lunati even the lighter je will survive 250. if done right..find a comptent machine shop let them set side clerance and pin clerance anything else is a band aid ... john

[sc racing]

Thanks guys
Steve