I have a set of JE pistons pn 131631 (detailed info: http://www.summitracing.com/parts/JEP-131631-8/) that are for a a 3.75" stroke and 5.7" rod. Called JE and they said the would work with a 6" rod and 3.5" stroke crank. That leaves .050" worth of length somewhere or am I missing something here? I know the correct way to do this is to have all the parts on hand and put it together and measure but I just have the pistons at the moment.

This is on a standard deck 95' LT1 block btw.

If anyone know if these pistons will work with a 6" rod and a 3.5 or 3.48" or should i go 6" rod with a 3.75" stroke crank please let me know.

Thanks.

 

Those are for a 3.75" stroke and 5.7" rod. You'll be above the deck with a 6" rod and 3.48" stroke. You might be able to squeeze it together with a 5.85" rod and 3.48" stroke.

 

Can i fix that with a thick gasket? and what about the 3.5 stroke?

Thanks

 

the problem is i already have some good crower 6in rods which i would hate to part with

 

No, you'd need .180" of gasket to put it together. To get that thickness you'd be stacking multiple gaskets up. A 3.5" stroke (why would you do that?) would be .010" worse.

 

no yeah i dont even know what i asked that ha

JE said to use a 3.5 stroke i have no idea how that makes sense

 

when you do your math set the quench as close as you can to .042

 

Thats the problem i didnt do any math i dont know much about all that, i just got a good deal on rods and these pistons and well now i have to figure out how to make them work ha

 

LT1s love the 3.75" stroke. Spend $230 and buy a crank.
And there's nothing magical about 0.042". 0.038" is at least as good.
Really, the best thing is to get the block bored and honed to match the pistons. Set the main bearings in, then some lube, then the crank. Repeat with the rods and pistons at each end of each bank.
Then it's easy to determine how mich iron has to be removed from where to get true Zero deck.
Then take it back apart and have the decking done.
Finish assembly with FelPro LTx head gaskets.
Simple.

 

Take crank stroke and divide by 2. Add that to rod length, and then add that to piston compression height which should be the height from piston top to center of rod pin bore.

That gives total length of assembly. Block deck is 9.025" undecked. 9.00" is zero deck.

3.48/2 = 1.74 + 6" rod + those pistons 1.425" height = 9.165" Thats .14" over the block deck...not going to work. 3.5" stroke or more is gonna make it worse.

If you have 6" rods and want a 3.75" crank, you need different pistons. If you want to use the 6" rods with a 3.5 or 3.48" crank, need different pistons.

If you want those pistons you will have to use 5.85" rods with either 3.48" or 3.5" crank. The 3.5 is 9.025" height, which means block cant be decked. 3.48 means zero deck will now be at 9.015"

Only way that 6" rod and those pistons will work is with a 3.20" crank or smaller.

 

okay lets say i keep the rods what pistons do you recommend for me, i need a low compression and well about $500-$600

you said a crank is $230.. a cast crank can hold the boost??

 

That depends on what you want to do with this motor. How much power and what rpms? How much boost? Cast cranks can be very strong as long as the casting is quality. I have seen a few cast cranks break but not from over powering them. It was a bad casting. What stroke do you want? JE should have pistons with big dish for 6 inch rods and 3.75 stroke. I have them for my motor except in the 4.125 inch bore size.

 

im running an eagle cast steal crank and it has seen the better side of 7000 rpms on many many occasions...without a problem. I would suggest the use of arp studs though for the main caps

 

are you n/a ? i found a used compstar crank for 350

 

I'm using compstar rods and crank in my twin turbo 401 with no problems so far. 850-ish hp and 6200 rpm so far.

CNCblocksnortheast.com. Carl can get you compstar stuff for the same price as Eagle forged cranks and rods. They are forged overseas but final quality inspection and machining is done here in the USA

I've used eagle forged crank and h beams in my 6800 rpm 383 which has hit 7000 a few times. Plus nitrous. 650 ish hp estimated. They are good too

 

yeha i was a little scared of the eagle china stuff... i have a set of new crower forged i- beams but i think im going to trade them for compstar h-beams, what you think?

 

Depends on the power goals man. Both I would think are capable of some decent hp numbers. I'm not too familar with the crowers but I know eagle H beams have been used to over 1000hp with L19 rod bolts. Compstars would be in the same boat.

 

well it not really the numbers because i just want to build it stronge, its a daily driver, and well i got offered an exchange my new 6in crower rods for h beam compstars that are lightly used... the word used doesnt make me feel great about it but i do need the 5.7 rods for the JE pistons

 

IF you dont pull alot of rpms and go with a 3.75 crank, use the 6" rod with JE piston 170817
http://www.jepistons.com/Products/170817.aspx

You could do a 5.7 rod as well, they have that piston.

If you go 350 go with the 5.7 rod and JE piston 131636
http://www.jepistons.com/Products/131636.aspx

Doesnt really matter. The rod bolts and tune will have more impact on reliability and power holding potential.

But the 383 will make more power on less boost and crapload more torque.