Magnum head and exh manifold ID

toolmanmike said

According to the "How to build big inch Mopar small blocks" book 1992-2003
You also have to use Magnum valve covers because they have 10 bolts instead of 5.
If you're planning to put Magnum heads on a LA you will need Lifters from a v-8 AMC, hollow pushrods (Mopar Perf. #P5007477) Magnum head gaskets (to block off the oil holes)the Magnum head bolts, and an intake manifold for a carbruetor.(all Magnums are fuel injected) There are only three intakes available for this conversion, Mopar# P4007381, Edelbrock "Air Gap" #7577, and Professional Products "Crosswind". I also looked to see if the 5.2 and the 5.9 heads are the same. They are. (60 cc. chambers,1.920" intake valve/ 1.625" exhaust.) The Magnums have a 10cc smaller combustion chamber which will raise compression about a point. They also have larger ports and bigger/lighter valves.

toolmanmike

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Couple of corrections;

1. You can use LA valve covers. The five bolts on an LA cover line up with 5 of the 10 on the magnum head, just use LA intake gaskets to cover up the extra holes. Follow the link in my signature line to my car and see pics of an LA block with magnum heads and LA valve covers.

2. You do not need a magnum head gasket but you do need magnum intake manifold gaskets. Unless, you redrill the heads to accept LA bolting. You could possible elongate the holes in LA intake gaskets but doesn't seem to be worth effort to me.

3. There are (4) intakes available. MP has both a single plane and a dual plane, then the mentioned Air-Gap and Crosswind. I have a Crosswind on my engine.

4. The chambers are 64cc's, I measured mine and most everyone else that has measured them gets around 64cc. On my 360 with zero decked pistons and a 0.039 thick by 4.180 bore head gasket I have 10.6:1 compression.


For those trolling the junk yards the quickest and easiet way to tell a magnum engine from a non magnum is the intake. All magnum engines have this large barrel shapped intake with the previously mentioned vertical bolting holding the intake to the heads. Plus port injectors. The 5.2/5.9's just previous to the magnun engine use a more conventional looking intake with throttle body injection.