Heads

[Dusty1]

Sorry to ask this, I know its an old, worn out topic for you guys. My X heads are in the shop now for a pin hole repair in an exhaust port, so I'm going to go ahead and let them do the valve job and install hardened seats ($8/hole). They need to know what cam I'm going with, which I know little about. You guys have all the knowledge, but I have few answers for the questions . 340 ci, 355 gears, ported & 2.02 valves, street & some strip. Any brand & size suggestions would be appreciated and anything else I need to do to the heads? shaved? Thanks

[71chally416]

Well hopefully they don't sink the Intake valves. You'll know they did when it seems slower than before. Were you having trouble with your exhaust valves or seats? Why bother with the hardened seats? I drove my 318 around daily for 4 years with '70 X heads and never had an issue with that running the crappiest unleaded regular I could possibly find. I also had regular STEEL valves, not stainless. I'm convinced it's an old wives tale that you need them on a street car, and for a part time once in a while hobby car they are definately not required.

[Dusty1]

No, no trouble. I just thought I had seen it mentioned on here a lot about the seats sinking with unleaded gas. I'd rather not if its not necessary!

[boydsdodge]

I sunk two valves on my 360 after about 10,000 miles.
73 castings.

[Chryco Psycho]

typically I would be looking at a K 56 Engle as the best choice for a street strip hyd

[71chally416]

I even had narrowed seats in mine. Didn't have much cam or valvespring though, and the motor had 8 to 1 comp at best so it never detonated and never ran hot. THAT'S what will kill exhaust valves and seats.  

[Dusty1]

Get the Engle with the valve springs. Right?

[Chryco Psycho]

or a spring with similar pressure from any decent supplier

[moper]

Repair a pin hole in the exh port? I'm assuming that's by welding. The whole head will need to be machined after anyway. I install 2.05 intakes in order to keep the seats out in the chamber like 71 mentions.

[71chally416]

I install 2.05 intakes in order to keep the seats out in the chamber like 71 mentions.

That's the only cure assuming the machinist is competent and doesn't sink them too. Hate to sound like Debbie Downer but I've seen so many bad valve jobs on Mopar heads it's an epidemic.I sometimes think the Chevy shops do it on purpose. Other shops just don't know any better. The worse set I ever saw were 906 BB heads ported by a reputable (with GM guys)speed shop in Jersey.

[Dusty1]

Yes, welding. Dover Cylinder Heads in Chattanooga, Tn. in business for over 50 years, specializing in crack repairs. The Mopar man there owns a 340 himself. I have no personal experience with them, but they were recommended to me by another machine shop.

[moper]

71, I here you. Worst case I've seen was out of a mass rebuilder...

Dusty - in order to weld iron, the whole head gets heated so the weld doesnt create local stress risers from the welded area. In that process, the deck surface warps and all the seats warp. So it will be getting all the machining done after the repair too.

[71chally416]

71, I here you. Worst case I've seen was out of a mass rebuilder...

Some of those mass rebuilders don't even use mandrels in the guides to pilot the cutters. 

The car the bad heads I saw used to run the same class at Atco back when I ran Pro. I was doing 10.70's>80's with my mostly steel 383 RR with a hydraulic cam and he was doing low 11's with his speed shop built roller cam'd 440 with the same type 906 heads that they ported in his '65 Belvedere I body. It had glass everything and aluminum interior and probably weighed 2,700lbs max. He blamed his poor performance and broken parts (valve springs, rocker gear and tail shafts on his tranny because he used a solid rear mount) on the brand car he was using instead of the shop that put his motor together and switched to Chevy.