Magnum Heads....

[Sublime69]

I have a 69 dart w/ a 318. I have a procharger going on it with a set of magnum heads that came off of an 01 Durango.

Heres my question: I sent them to the machine shop to have cleaned up and but bigger valve springs put in them. Well after they cut the spring pockets they realized that they couldnt find any locks to fit the valves... so i ended up putting a set of stainless 2.02/1.60 valves in them.

Some one just told me yesterday that those heads get their strength from the valve seats? and if you open them up for larger valves, they will crack.. This same guy said he did the the same thing to a pair of heads and ended up crackin 5 chambers from the intake valve to the spark plug hole.

Dose anyone know anything about this??

Thanks

 

[AIRBORNE]

I've heard of this before, but never saw it first hand for my own eyes. Find out what kind of seats the machine shop put in after they opened them up. If they were "hardened" seats then I don't see how they would be any different from the stock magnum seats but I'm no expert either. I ask some of the local guys I know and see if they know anything that may help you more. Take it easy man!

 

[Sublime69]

I've heard of this before, but never saw it first hand for my own eyes. Find out what kind of seats the machine shop put in after they opened them up. If they were "hardened" seats then I don't see how they would be any different from the stock magnum seats but I'm no expert either. I ask some of the local guys I know and see if they know anything that may help you more. Take it easy man!

Thanks! let me know what ya find out..

 

[AIRBORNE]

From everyone I've talked to it seems to be the head castings that are the problem. The area in the combustion chamber is thin and the crack when thay get a little too warm. The engine doesn't have to overheat for this to happen either. As long as they were pressure tested after the new seats were installed and you keep an eye on the water levels, I'd suggest running a 160 deg. thermostat also, they should be good to go. I'm no expert by any means but all my research seems to point in this direction, hope it helps.