1970 340 "J" Heads- Oversize Valves?

[motorparts92]

I am beginning my build on a 70 model 340. I have the original, decent set of J heads which i am going to try to beef up a bit. The only oversize valves i can find for these heads are 2.08/ 1.65. My question is...will these function properly? I realize the 202/160 valves are very close together as it is, and that the 208/165s are just a few thousanths bigger. Will i have any problem with these valves?? Thanks!

-Young Grasshopper-

 

[PettyBlue72]

There is no need to put larger valves in a set of big valve J-heads. These heads are the best flowing heads next to the w-2 heads mopar produced in the 70's. Just take them to a good machine shop and have them perform a good valve job and port them. Add a set of stainless 2.02/1.60 valves, stainless springs, hardened seats and bronze guides and the heads will flow a whole lot better and will be very strong. You will have to have the intake and exhaust manifolds gasket matched to the newly ported heads.

Joe

 

[Meep-Meep]

There is no need to put larger valves in a set of big valve J-heads. These heads are the best flowing heads next to the w-2 heads mopar produced in the 70's. Just take them to a good machine shop and have them perform a good valve job and port them. Add a set of stainless 2.02/1.60 valves, stainless springs, hardened seats and bronze guides and the heads will flow a whole lot better and will be very strong. You will have to have the intake and exhaust manifolds gasket matched to the newly ported heads.

Joe

X2.