[kozmo69]

Hello, im new here

I have a 396 with L2242 pistons, but Im not sure if I can run these heads which are casting # 3931063. i found this:

3931063....68-69...oval..CLOSED..396, 402, 427, 101cc chamber


I don't know the exact specs of the pistons but, from what I hear that these domed trw L2242 pistons should give me a compression ratio of 11:1, and are a closed chamber piston, What heads do you guys suggest running? Will I be ok with the heads I have now?

Thanks

 

[JC396]

I'd run them. Some others here can suggest a camshaft profile that will "bleed" off some compression and make it able to burn pump gas and not spark knock....I have those same pistions with "820" heads 113 cc. I calculate about 9.75 compression on mine....

jim

 

[Jason Snyder]

I'd run them. Some others here can suggest a camshaft profile that will "bleed" off some compression and make it able to burn pump gas and not spark knock....I have those same pistions with "820" heads 113 cc. I calculate about 9.75 compression on mine....

jim

Yah , but if he ever puts his foot in it ! it will detonate , so might as well put a 4 cylinder in it ! If you plan on driving it ,and gettin some every once in a while , get some different heads . Those 063 heads are very valuable to the guys with low compression 454 engines ! Do a swap for some 049-781 heads . those 820 heads are good as well .

 

[kettbo]

Welcome to Team Chevelle.
Got a first name 'kozmo69?'

You'll have much more compression than 11:1.:yes:
They are rated with 106cc head...you have 101cc heads.
Best advice if you must run those pistons is to get 049 or 781 heads on there, knock the compression down to something around 10.5:1

Many of us in the NW have 427s with L-2268 forged 11:1 pistons. We tone down the compression a bit with large chamber 781 and 049 heads

 

[kozmo69]

Welcome to Team Chevelle.
Got a first name 'kozmo69?'

You'll have much more compression than 11:1.:yes:
They are rated with 106cc head...you have 101cc heads.
Best advice if you must run those pistons is to get 049 or 781 heads on there, knock the compression down to something around 10.5:1

Many of us in the NW have 427s with L-2268 forged 11:1 pistons. We tone down the compression a bit with large chamber 781 and 049 heads

thanks, my names josh.

thanks for the info guys, So I guess I have to look for another set of heads,I was really hoping I didn't have too because the ones i have now where rebuilt and also original, but I had know idea the L2242 pistons where rated at 106cc.

 

[SWHEATON]

FYI, " if " those pistons have solid domes maybe you could simply have a local machine shop use a cnc machine to remove the same exact amount of material(to retain proper ballance especially if bottom end was already balanced) from the domes on each piston to mimick the smaller .182 domed L2240 speed pro psitons that yld approx 9.6 comp with the smaller domed pistons & 100cc chambered lrg oval port 063 heads.

Since your 063 heads are newlt rebuilt i would try to get a good deal on having the domes shaved($150-$200) it could save you alot of $ not havng to buy & rebuild another set of 049/781 heads(min of $400-$600+) and or buy new forged pistons ($450-$500+) & maybe new rings too @ $100+.

Scott

 

[kettbo]

thanks, my names josh.

thanks for the info guys, So I guess I have to look for another set of heads,I was really hoping I didn't have too because the ones i have now where rebuilt and also original, but I had know idea the L2242 pistons where rated at 106cc.

I did have the 101 cc closed chamber ovals on my 427 with the similar 427 L-2268 11:1 pistons. IIRC, the calculated CR was 11.8:1 It hauled ass but would not run on pump gas. :noway:
I had big 2.19/1.88" valves installed in a set of 781 open chamber oval port heads.... Much happier now at around 10.5:1.:thumbsup:

Lots of guys will trade for your 063 heads....


BTW, my old 063 heads with just 3000 miles on them are in use again. I threw them on a low compression 454 shortblock last fall.....now have a usable 8.8:1 CR in my 70 Elky's 454.

 

[gotago]

thanks, my names josh.

thanks for the info guys, So I guess I have to look for another set of heads,I was really hoping I didn't have too because the ones i have now where rebuilt and also original, but I had know idea the L2242 pistons where rated at 106cc.

CC your heads to find out what you really have. I have a set of 215s that I measured and they were a little larger than 101ccs. I built a 439 out of a 454 block and 396 crank and used my 215 heads. I had to grind my heads for the piston to clear and ended up with 109ccs give or take a couple. My compression measures out at 11.1:1 and I'm on the ragged edge of running pump gas. I get away with it because my cam has 243 degrees of duration which bleeds off some cylinder pressure as someone mentioned. Finding a cam is one option, Scott mentioned another, and finding a new set of heads is a third. Finding a cam and shaving the pistons require you to know exactly what you have as far as chamber volume and deck clearance so you know exactly what your compression will be.

 

[SWHEATON]

I think if he has the higher domes shaved to specs of the shorter .182 domed speed pro L2240 pistons there is no reason they have to go nuts figuring out deck height/blok & head decking etc.

Because if the machinest shaves each dome done to that exact same dome height that the stock speedpro L2240's have then it would be like installing a new set of those pistons that speed says ylds approx 9.6 comp with avg repl head gasket thickness & 100-101 cc chambered heads . But as always head & block deckin (affecting quench) will increase the comp some too so keep that in mind. Should maybe chk all pstons wieghts prior to shaving domes to lower .182 dome heith specs. Then after that recheck /reballance each piston to match it's prior pre dome shave weight to keep the ballance of the rotating assembly in check.

Scott

 

[gotago]

Because if the machinest shaves each dome done to that exact same dome height that the stock speedpro L2240's have then it would be like installing a new set of those pistons that speed says ylds approx 9.6 comp with avg repl head gasket thickness & 100-101 cc chambered heads.
Scott

I have a set of the L2240s but they're 30 over, don't know if he can use them. May save him some trouble. As far as measuring goes, yes its painful at times but then you know for sure what you have rather than just looking at specs IMHO