340 build advice

[CUDACOX]

Hi all, I picked up some new 30 over pistons in Carlise.They are from what I have looked up...8.5 CR L2385F Fed/Mog.I have the 1971 340 all stock that I bought at the end of the winter.I want to build a nice street engine for pump gas that will make about 375 H.P. I will be using the stock J heads Comp Cam 286/491.
I have a LD340 intake to use.Any advice would be great! Please keep in mind I'm on a fairly low budget.Thanks in advance!! Craig.

 

[Snake]

Dont think you will get there with 8.5 pistons.

 

[C130 Chief]

More compression. The stock 340 made 100 less HP with a lot more compression and not much less cam. I'm willing to bet Comp recommends at least 9.5 for that cam.

 

[djwhog]

Yep you need to get into the 10+ range and esp with more cam buddy

You can gain some with head milling, but i would look to Ross etc for a nice set of forged higher compression pistons as a start and maybe open up the j heads with larger exh valves if you want to get into the hp per cu inch range.

 

[RustyRatRod]

That would make for a great nitrous motor Craig. You'd get there and then some then.

 

[dano]

Just add a Procharger and you'll easily get 375hp.

 

[CUDACOX]

Thanks all, I couldn't tell when I bought them.Still was a good deal.Might have a trade in the works!

 

[mjs69gts]

nitrous or turbo it

 

[4spdragtop]

You gonna do any head work Craig??

 

[CUDACOX]

Not alot Steve,just a nice clean up.

 

[4spdragtop]

If they are j's, maybe get the bigger valves in them

 

[Moparhead64]

Try the aftermarket magnum heads,closed chambered heart shaped combustion chambers, 1 6 rocker ratio, best flowing smallblock head( better than any L A),pedastal or shaft mounted rockers, LA or magnum intake, Indy designed possible complete kit heads ,intake, bolts or studs ,gaskets .

 

[CUDACOX]

If they are j's, maybe get the bigger valves in them

J's have the larger valves,same as X.

 

[Snake]

J's have the larger valves,same as X.

Not all JSSSS have the big valve.

 

[CUDACOX]

Not all JSSSS have the big valve.

Mine is a 1970 motor came out of a 1971 Demon.It has the large valves.Same as X But you are right,not all J's have them!!

 

[CUDACOX]

O.K. Does any great member have a new or nice set of used 30 over 9.5/10.1 340 pistons for sale?? Please let me know. Thanks, Craig.