ok theres a guy selling a set of JE pistons part # 181916. now on JE's website they say there for a 3.50 stroke with a 6" rod making 11.2cc on a 58 cc head. He's telling me that they will definantly fit a 3.875 stroke with a 5.850" rod but not a 6". Does this sound possible? It's a pretty good deal on the pistons but i dont want to buy the wrong thing. It's a -5cc flat top forged piston and I WILL be running them in a 396 setup with a 5.850 rod on nitrous. Any info would be really appreciated. thanks guys
Rob

 

9.025-(3.50/2)-6= 1.275 compression height (assuming zero deck)

9.025-(3.875/2)-5.85= 1.2375 compression height

1.275-1.2375=.0375

In case you don't know..... compression height is the distance from the wrist pin center to the top of the piston.

Which means that that piston (#181916) would be sticking out of the block .0375, almost a millimeter. I want to see what JE's comp height is (where they place the piston down the bore) so I'll be back.

-Mindgame

 

Uh , i will definantly be waiting on your reply cause so far it doesnt sound to good for these pistons. and thanks for the fast reply
Rob

 

Ok, JE puts the piston .025 down the bore (9.025 deck height) so you actually be .0125 ((.0375-.025) out of the top of the block. Not a problem.... some guys actually like to run the piston slightly above the deck. With a .049-ish gasket (compressed) that'll get you a .0365 quench height and that is about right.

Some of this may be unclear.... so let me know if I lost you along the way.

-Mindgame

 

so basically if i run these with a regular .039 gasket on a 5.850 h-beam with a 3.875 stroke it should be fine? im thinking somewhere around 11.5:1 comp. in my 396. does this sound like a good setup? hes asking 350+shipping for these pistons and says there brand new with light weight wrist pins and spiral locks. if i knew how to add a link to this thread i would. sorry

 

A .039 thick gasket will put you too tight on the quench height @.0265.
.035-.045 is usually considered "ideal" for steel rods but you start going tighter than this and you could run into some contacting problems due to piston rock, stretch, etc.
No biggie.... just buy a .049-.059 thick gasket. I use FelPro and Corteco and I'm sure one of them has a gasket in that thickness range. That'll get you where you need to be.

How many miles were on these pistons? I wouldn't use them without a zyglo check so figure that into the cost along with your shipping.
To post the url link, just go to the thread, "copy" the url in your browser and paste it here.



-Mindgame

 

he's SAYS there brand new in the box never run, but i still planed on getting them checked.Im taking my block,crank,rods,pistons,and heads all to the machine shop at the same time and tell him to work his magic.(he's awesome with machine work) anyways heres the link if you just wanna check it out. again thanks for all the help cause i was seriously confused but i think i get it now. aint it scary that im going to be the one building this motor ROB http://web.camaross.com/forums/showt...6&goto=newpost

 

Its ok Rob, I built my first engine once too.
Its either that or let someone build it for you. Just buy some books on engine assembly/blueprinting and go slow... check everything thrice.

Good luck!

-Mindgame

 

hey mindgame if your still keeping up with this thread...would it be to my advantage to go with a 5.7 h-beam? i havent bought the rods yet so its still up for debate. im kinda skidish about cutting it so close with the 5.850 espicially if im not gonna really see an improvement. i mean if the 5.850 is the way to go then thats what i'll do but which one would actually be the best? thanks AGAIN
Rob

 

You can't run those pistons on a 5.7 rod, they'll be .1375 down the bore at tdc. Run the numbers..... 9.025-(5.7+1.25+(3.875/2))= .1375. Even if you cut the deck to 9.0", you're still .1125 down the bore..... no good.

This brings up another point.... your machinist is gonna want to cut the decks on the block, that's gonna put the piston even higher above the deck (talking 3.875/5.85rod setup here). Have you bought these pistons yet??
I should have made mention of this last night but I wasn't thinking too clearly in my response. Your best bet here.... run the right pistons for the setup because there isn't a rod length option thats gonna set everything where you want it. What you want is to have the piston 0-.010 down the bore at tdc... and thats taking a deck cut into account (9.0-9.01 deck height).

-Mindgame

 

man you are so right. i just read me e-mails today and i had a reply from nu-tek and hes pretty much telling me the same thing.(that those pistons wont really work) after the block being decked.before its all over with i may just end up buying a 396 kit from them already balanced and ready to go. well either them or combo motors not sure which one yet. oh to answer you , no i havent bought them yet,and i guess i might not. man once again thanks so much. from the looks of things you might have just saved me about 400 bucks and who knows how much more after it was all said and done with
Rob