Will the heads off a 1992 360 magnum fit on a 1973 318 ?

Yes, but

valve train is different, from the pushrods up.

Intake bolt pattern is different

You'll have to double check and correct accessory mount alignment.

yes but as said lots of different stuff valve train push rods,and lifters, also the way the heads are oiled is totally different. do your research its not just a bolt on.

Can be done, but usually you're better off to swap in the whole magnum engine. The magnum heads will need different pushrods and lifters. The angle of the intake manifold bolts is different. Guys used to redrill them to accept LA manifolds. These days you can run aftermarket carb/magnum intakes to solve that problem. By the time you do all that you can swap in the whole magnum engine and enjoy the benefits of better compression ratio and moly rings.

From the archives:

http://www.moparts.org/Tech/Archive/smallblock/7.html

Good info. Thanks

Some of that info is dated and some of the MP part numbers are N/A.

or rebuilt the old LA engine with the Magnum pistons and rings too.

That opens up it's own can of worms. Balance is different and the rod needs narrowed to fit the Magnum piston. be easier to run higher compression LA pistons.

The Magnum engine gets you a roller cam as a bonus. You could probably go to a wrecking yard and pick one up that is equipped with fuel injection and find visible crosshatches in the cylinders.

You'd be hard pressed to find a Magnum that was NOT fuel injected since they all were.

You can also get the 318 and 360 LA's with roller cam provisions.

FWIW the 87 318 I have for my 65 Cuda has visible cross hatches (stock bore) and was neither a Magnum nor fuel injected. The cross hatches are more a case of having moly rings and not because of FI.

The 318 from my mother's '86 Fifth Ave. with about 130K miles still had noticeable crosshatch, no ridge, and all the bearings could have been reused.

Yes much of that could be attributed to the factory moly rings.
I believe that another reason is they never developed much cylinder pressure because of the 2-barrel carb, small cam, small heads. Cylinder pressure loads the rings against the cylinder walls. Also these cars were a favorite of the retired set so they weren't driven hard. I know, all you guys are retirees and drive fast, but you weren't likely to go to your Chrysler dealer and order up a Fifth Avenue, preferring something with a little less stodgy appearance.

R.