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View Full Version : Scored a set of 915's



Piper
01-12-2013, 07:30 PM
For cheap, looks like someone already put a larger exhaust valves in (I believe they are stainless did the ole magnet trick)


I am putting together a very close to stock 440. Its a 1972 bottom end and retains the factory pistons(they sit in the hole .125) So hoping the 915s will bring up the CR slightly from 8.2:1

To make them serviceable (want to keep it low buck) what do you guys think? Clean and surface them bolt them on and call it a day?

ws27
01-12-2013, 10:50 PM
I think there is a really nice running engine located in Mass that is already running, hehehe.


...Maybe that should be hint, hint, hint.

4264door
01-12-2013, 11:13 PM
A guy I know used to use 915's on his 1973 383 street/strip 'Cuda. He actually went through 2 sets of those heads. The problem we found was the water jacket hump on the bottom side of the head where it meets the block surface, just above the header flange in the center of the head started to develop water leaks to the point the head had to be removed and welded. The welding ended up being a bad idea as the metal is so thin there. His second set did the same thing and we surmised it must have to do with the fact big-tube headers were being used causing more harmonic vibration ending up being absorbed into the head surface which would be usually in a stock situation, absorbed by the cast iron exhaust manifolds. We filled the crack on the second head with JB Weld and it held for a few hundred miles but started to leak once again. That was the theory at the time.

I think a better head other than the 906 head is the motorhome 440 engine cyinder head. They have better cooling passages and flow nicely and really respond to larger valves and some mild pocket porting. You did mention you got these 915's for cheap so sure, go ahead and use them by all means. They will bring up your compression and also a need for higher octane gas, maybe, depends on your timing and choice of ignition components. Check the inside of the intake and exhaust runners for cast iron flashing. Grind that flashing down to the surface to improve flow and decrease the chance of detonation and run-on after shutting the engine off, due to the flashing being still red hot from the combustion sequences. Raw fuel in the intake and combustion chambers will ignite when that flashing is still hot.

The supply of 915's out my way is now exhausted and it is rare to find a good useable set. I do know some guys who own high dollar 1967 Dodge musclecars with the 440 magnum engines who like to keep a few sets of 915's around because they were the stock head of the day that brought the 1966 440 up to snuff in the performance department. Part numbers on the head also count for a concourse correct restoration. I wish I had even one good set in my garage but I don't currently.

Piper
01-13-2013, 12:15 PM
thanks for the input, I am trying to figure out what that compression I will end up with (I hear those 915s left the factory anywhere from a 78 to 84cc) maybe I will try that DIY method I posted in another thread


I am thinking of surfacing, cleaning and bolting them on like I said pretty much a stocker just want it to able to scoot me around to shows this year