je piston question

[dallasb84]

so i got done building my bottom end tonight.

its a obd2 ls block with a gsr crank, gsr eagle h beam rods, and je standard size pistons. . .

heres my question. the je pistons feel a bit sloppy in the cylinders. when comparing the pistons to the ls ones, the skirts are wayyyy smaller so the surface area on the cylinder walls is less. well im guessing now 1/32" or so wobble with the pistons..... i just cant believe this is kosher.

when i ordered from je i ordered pistons for a 91mm block standard bore. i lightly bored the block and didnt remove much material. just enought so that the ring have something to seat with..

well im hoping someones gonna tell me this is normal and je pistons are usually sloppy.

i know im not giving you numbers with this question... but i think there might be some people that can chime in.

[punkr6]

the block is 81mm not 91, also you should have only honed the cylinder if your going with standerd bore pistons, not bored it as stated. You need to check the piston to cylinder wall clearance on each cylinder. This is VERY important. don't run it till you do...

[Formally...]

First skirts on the piston being smaller don't matter that much. If the motor is build right with the correct ring tension then the skirt will not hit the cylinder walls. Next you need to check the piston to wall clearence but DO NOT GO BY THE HELMS MANUAL. If you are running forged pistons the ptw clearence will be different then when running stock cast pistons. Also, is this motor going to be turbo, nitrous, or na. This will change the ptw clearence some also.

[dallasb84]

sorry yall the pistons are 81mm and i only lightly honed each cylinder.

[Catnip]

Glad to hear it's coming together man. How'd everything look?

[dallasb84]

i will later be running boost on this motor. i just looked it over and tried wiggling the pistons in the cylinder. id say maybe a 1/64th" or so play. i also put my hand over cylinder and turned the crank with a socket and kinda jarred it to try to get the piston to slap but it wont.

as for ring tension... im pretty sure i got that right it takes about 10# torque to turn the motor on up and down strokes....

all my ring gaps are perfect and my plastguage on the bearings are all perfect. end play is good too.


the little bit of slop in the pistons is all im worried about. i read online that with forged pistons they do tend to slap a bit on cold starts and once the engine warms up it goes away.......

[dallasb84]

catnip : the bottom end was spot less. not one scratch on the cylinder walls. all the bearings showed no discoloration.

only problem is cylinder #2 intake valves were so caked with carbon im suprised it passed a compression test. the valve stem seals are bad. hopefully i can clean the valves up when i take em out.

at first glance i thought the valves were melted..... did u spray this motor???

[Catnip]

catnip : the bottom end was spot less. not one scratch on the cylinder walls. all the bearings showed no discoloration.

only problem is cylinder #2 intake valves were so caked with carbon im suprised it passed a compression test. the valve stem seals are bad. hopefully i can clean the valves up when i take em out.

at first glance i thought the valves were melted..... did u spray this motor???

Never sprayed or boosted as far as I know, definitely never in my care. Maybe a weak injector(s)? It did get outrageous gas mileage (30mpg city easy).

[dallasb84]

no biggie im getting a new head for it..... for free