383 426 heads casting 2406516-6

[o1heavy]

according to the casting numbers these came off a 383-426 wedge engine

i have a 78 d300 with the stock 440 and stock heads not sure which heads but i'am sure they are low compression emission heads

would the 426 heads be worth swapping onto the engine hoping to gain alittle bump in compression

thanks for the input

 

[moper]

They'll give you compression, but the factory '78 heads are probably a better choice for what you actually have. The early heas have no induction hardening on the exh seats and I'm sure a truck needs them. If you want a little more cylinder pressure I'd add a small cam to it.

 

[o1heavy]

after a little research i agree
just looking to make it run a little better / which it doesnt run to bad
after the intake install it ran a 16.81 on the g-tec

going to check cylinder pressure and then start looking for a small cam

 

[cosgig]

The 78 heads are probably the "452" heads, which are basically the 906 heads with hardened seats. No need to change those to the 516's with a much smaller exhaust valve, closed chamber and no hardened seats. Raising the compression on a 78 motor effectively involves more than just a head change, especially to the 516!! JMO, Geof

 

[o1heavy]

looking for a set of pistions that will net me roughly 9 to 1

its just tough to dissamble a engine that runs great but man is it slow
been in to mopars since i was a teenager but this is my first big block

likly going to remove and repair to my liking this winter