ls1 piston size needed

[sloLs1]

ok im trying to find out what the specs of a stock (98 ls1) piston are.... per say i was going to order a set and they needed all the specs to make them?!?!? ive found a few different specs and im not sure how reliable the source is!!! any help would be greatly app. like always!

[BAD LS1]

3.898" bore 3.622" stroke. You will need pistons to fit a 6.100" stock rods and that have .940" wrist pins. Note stock rods are press fit pins. you will also need rings to fit those pistons/bore 1.5mm 1st,2nd 3mm oil. You will have to obviously get the thing balanced too. The bores should just need a flex ball honing to seat the rings.

[sloLs1]

3.898" bore 3.622" stroke. You will need pistons to fit a 6.100" stock rods and that have .940" wrist pins. Note stock rods are press fit pins. you will also need rings to fit those pistons/bore 1.5mm 1st,2nd 3mm oil. You will have to obviously get the thing balanced too. The bores should just need a flex ball honing to seat the rings.

yea the block looks great... im just going to hone it and throw new bearing in it. Also having the crank polished. Havent decieded what kind of headgasket to run yet.... prolly just get a set from the dealer.


BTW i dont know what id do without BCM!!! id be lost! also BADLS1, your a very big help to me!

[BAD LS1]

SEALED POWER Part # L2621F is the most cost effective forged piston for these motors. it may have a slight designation change to get them as a kit instead of individual, some quick googling should turn up a kit of 8... These are what i ran in my prior motor. If you have the means, get the oil holes chamfered, they are knife edged stock and can almost cut your finger on them.

[Crawlin]

GM MLS gaskets. cheap and effective unless you are gonna really find the time/money to get the right finished to the deck of block/heads.

[BAD LS1]

GM MLS gaskets. cheap and effective unless you are gonna really find the time/money to get the right finished to the deck of block/heads.

Depends on the vintage of his heads... they may be 00' and older and have the "U" notch in the deck and require the graphite gaskets. The MLS's would open up a niagra falls type leak if used in conjunction with old U notch heads.

cast #'s 339, 806, 862 and some early 853 are gonna have the U notch. 241's and late 853's were the first to have the flat decks.

[Crawlin]

i forgot how exactly the differences were. Good info Tom. I remember Big Mike mentioning it, but I've never personally ran into the issues

[Yellow2k1vette]

Depends on the vintage of his heads... they may be 00' and older and have the "U" notch in the deck and require the graphite gaskets.

I have notched 862 5.3 heads, and have been running Cometic MLS gaskets for the past 12k miles with not a drop of coolant missing. The previous owner of these heads claims to have run them with GM MLS with no problems too.

I'm not 100% sure about the GM MLS (at least not from personal experience), but I do believe GM soon corrected the MLS design to accommodate the notch and be backwards-compatible many years ago after people discovered this to be a major problem.

It might still be preached on LS1tech today, but old stories are tough to kill sometimes. I do know for sure the Cometic MLS WILL work with notched heads.

[sloLs1]

thank you for the PN#! i will check into that....


also i have 806 heads.... is it worth getting them ported?? like stated before, im gonna be running a "smaller" cam something at or under .600 lift and 232/234 duration... (im looking at The Texas Speed Torquer 2 232/234 .595/.598)


how much would i benifit from a ls6 intake/throttle body/maf over a stock ls1?!?!


this is turning into a build thread!!!!!

[Beagle]

I can get parts from GM at cost let me know if you need anything.

[BAD LS1]

thank you for the PN#! i will check into that....


also i have 806 heads.... is it worth getting them ported?? like stated before, im gonna be running a "smaller" cam something at or under .600 lift and 226/228 duration...


how much would i benifit from a ls6 intake/throttle body/maf over a stock ls1?!?!


this is turning into a build thread!!!!!

I have a set of 243 ls6 heads id sell for a decent price that has minor bowl porting and intake matching and prc double springs and titanium retainers. only issue is one head needs 1 new intake valve, it deformed on me and was being allowed to hang open. they are nice otherwise and great sleeper improvemebt over those 806's.

[sloLs1]

I can get parts from GM at cost let me know if you need anything.

so can i!!!

[BAD LS1]

I have notched 862 5.3 heads, and have been running Cometic MLS gaskets for the past 12k miles with not a drop of coolant missing. The previous owner of these heads claims to have run them with GM MLS with no problems too.

I'm not 100% sure about the GM MLS (at least not from personal experience), but I do believe GM soon corrected the MLS design to accommodate the notch and be backwards-compatible many years ago after people discovered this to be a major problem.

It might still be preached on LS1tech today, but old stories are tough to kill sometimes. I do know for sure the Cometic MLS WILL work with notched heads.

Cometic's are a different story. I was referrng to GM MLS's with the silicone beads that seal the water jackets. Cometics have asealing material that covers the entire surface.

I know from personal experience GM MLS gaskets plus the notched heads will leak. They drip coolant right above the motor mounts. I made this fatal mistake on my car in 02' with notched patriot heads and the gm mls's. This is why GM still offers the graphite gasket 12558809 and 12558810 for L and R for these older motors. I used these fore mentioned gaskets on my old 346 with 15 lbs of boost and made 700 rwhp with no issue too, so they work well too if budget is a concern.

[sloLs1]

I have a set of 243 ls6 heads id sell for a decent price that has minor bowl porting and intake matching and prc double springs and titanium retainers. only issue is one head needs 1 new intake valve, it deformed on me and was being allowed to hang open. they are nice otherwise and great sleeper improvemebt over those 806's.

hmmm.... well my heads are brand new. i do need to upgrade the springs and reatiners. Yours need a complete freshing up it sounds like?!?!

[BAD LS1]

these heads will raise the CR to 10.5 and make 25-30 more whp too. It just needs one new intake valve and the seat cut for it. i had gone through and did a 3 angle valve job on them 2k miles ago and the guides are perfect they may got 10k miles total on them since new. if you got brand new ones, no biggie. these ones will be for sale soon as im gonna fix them.

retainers are not mandatory if your gonna run a 918 beehive spring, if you go double then yes you will need to change the whole shit.

[sloLs1]

these heads will raise the CR to 10.5 and make 25-30 more whp too. It just needs one new intake valve and the seat cut for it. i had gone through and did a 3 angle valve job on them 2k miles ago and the guides are perfect they may got 10k miles total on them since new. if you got brand new ones, no biggie. these ones will be for sale soon as im gonna fix them.

retainers are not mandatory if your gonna run a 918 beehive spring, if you go double then yes you will need to change the whole shit.

tempting but i may just stick with mine. ill prolly order the kit from TSP, cam, springs, push rods for under $600. then i just gotta order the slugs, bearings and gaskets and this motor will be ready to rock!


looks like the pistons will be a few week wait though

[turbogarrett]

I have a set of cometic .041 gaskets for stock bore if you'd be interested. They are reusable, got an ls2