Piston to wall clearance

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OK guys, I have a very old but brand new set of cast J&E pistons for my 331 rebuild. These pistons have been sitting on a speed shop's shelf for 30+ years and are of the full skirt, zero taper variety. They use stock rings and have a compression ratio of approximately 8.0:1.

Here's the question: J&E no longer has any technical info on these pistons but they recommend (rule of thumb for cast pistions) a cylinder wall clearance of .002. This seems a little tight to me, even for cast pistons. Has anyone had any experience with full skirt zero taper pistons? My machinist seems to remember they used to use about .005. Any help would be appreciated.

Thanks

[moe74]

Moe here. .002 to .001 is just fine for cast pistons in a non-race engine. Just dip the entire top of the piston in oil, before you put the ring compresser on. Oil the wall with the E.O.S. that you got from the Dodge or G.M. dealer. But dont pay more than 8 or 9 buks, just find an other dealer. The E.O.S. is the ONLY way to get the zinc addative back in your oil. The EPA made all the auto oil makes take it out in1999. You MUST use it on new lifters and cams. It works good for bearings, pistons, rockers, ect.. And add one 16 oz can at each oil change. If you are useing dino oil. You dont need it if you use syn. oil. Oh by the way. You DID scrub ,the newly honed walls, Lava hand soap & water & a scrub bush. To get ALL the honing grit out, DIDnt you? Then spray it down with wd40 so doesnt rust. Then use a new cloth baby diaper to see if its clean. If you can run the diaper through the cyl. and all it gets is clean oil then its clean enough for the pistons. The entire engine should be that clean. Ok Ok thats enough rambing
Moes gone

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Moe here. .002 to .001 is just fine for cast pistons in a non-race engine.

Thanks for your input but for full skirt zero taper pistons, those clearances are too tight. A fill skirted piston will expand more than modern pistons so they require a bit more clearance. I wound up using .005.

[moe74]

Sorry about the bad info. Iam not famular with that type of piston. I guess a cam ground piston is totaly different. Sorry. Moe