Motor Home versus Passenger Car heads (same year) - any difference???

[69SportSatellite]

Curious about something, and if this has already been discussed, please feel free to direct me to the thread:

My "How to Rebuild the Big Block Mopar" book lists unique cylinder head casting numbers for 1974 and 1975 400/440 heads, e.g., 3769902 and 3769975 as being "Motor Home" heads...even though the valve sizes are the same as for passenger cars: 2.08 and 1.74.

My understanding from what I've read here on FBBO is that the M/H engines were lower compression, but were the heads any different in those years in terms of flow, combustion chamber, or? I suspect they are the same as the passenger car heads, but wonder why they'd have a different PN if that is the case.

Thanks - always trying to learn!

Chris
Sacramento, CA

 

[daredevil]

I may be wrong but I think that they have More water passages . The cooling passages are different.Heres what I found searching the net.Quote'As explained to me by an old Chrysler mechanic. One of the differences you will find between the 440-3 and the 440 used in street cars, is a longer coolant path between the heads and the block. This is accomplished by including an extra pass from the block up thru the head and back down thru the block again. Since the heads from the 440 do not have this path in the head, using them on the 440-3 is the same as plugging them off..The resultant overheating situation will destroy the engine in short order. Although they are rare, I have also been told that heads from the 413 engine may be used as a direct replacement for those of the 440-3.