Cylinder head choice

[cadeedmiston]

I've got a 72 318 with the 318 fast burn heads
Im planning on street use for just something fun
I have the camshaft picked out but I'm looking at 340 j,x or new aluminum heads.
Just looking for advice and anything to keep in mind when rebuilding the engine. If anyone has heads for sale I'd love to look as well.

 

[Kern Dog]

Some people try using the 5.2 and 5.9 Magnum series heads.
They flow better than any LA series head, they have higher compression and are OEM on every Mopar V8 from 1992-2002.
To use them, there are a few differences but it is a worthwhile idea.

 

[cadeedmiston]

Okay, would they bolt up the same? And how much is different I'm not familiar with that era

 

[Kern Dog]

In the early 90s, Ma Mopar let the Jeep and AMC engineers run amok and redesign the old fashioned LA series engine to update it. They changed them from 318 and 360 to the 5.2 and 5.9L "Magnum" series and were used in trucks ands vans only at first, SUVs later.
Changes included the elimination of shaft mounted rocker arms to a pedestal mount similar to the Chevy V8s. They changed from shaft oiling to the heads to pushrod oiling. They used roller camshafts and lifters. The valve covers went from a 5 bolt design to a 10 bolt for better sealing. There are numerous small changes between the LA and Magnum series, more than I am aware of.
Using the Magnum heads on an LA engine does require you to find an intake manifold since the Magnum uses a different manner to attach the intake.

 

[cadeedmiston]

In the early 90s, Ma Mopar let the Jeep and AMC engineers run amok and redesign the old fashioned LA series engine to update it. They changed them from 318 and 360 to the 5.2 and 5.9L "Magnum" series and were used in trucks ands vans only at first, SUVs later.
Changes included the elimination of shaft mounted rocker arms to a pedestal mount similar to the Chevy V8s. They changed from shaft oiling to the heads to pushrod oiling. They used roller camshafts and lifters. The valve covers went from a 5 bolt design to a 10 bolt for better sealing. There are numerous small changes between the LA and Magnum series, more than I am aware of.
Using the Magnum heads on an LA engine does require you to find an intake manifold since the Magnum uses a different manner to attach the intake.

Okay, so If I do the magnum heads I need an intake, rocker set, valve covers and pushrods? But would I have to change from flat tappet camshaft/lifters as well? I'm just trying to get a good idea so I can order everything I need all at once so I don't mess anything up when I go to install it all.

 

[icetech]

I've got a 72 318 with the 318 fast burn heads
Im planning on street use for just something fun
I have the camshaft picked out but I'm looking at 340 j,x or new aluminum heads.
Just looking for advice and anything to keep in mind when rebuilding the engine. If anyone has heads for sale I'd love to look as well.
View attachment 1837627

I use Trickflows on my 318.. they work well but you will end up around $2900 by the time you get rockers and pushrods and such..

 

[cadeedmiston]

I use Trickflows on my 318.. they work well but you will end up around $2900 by the time you get rockers and pushrods and such..

I appreciate it but cast iron is the only thing withing my price/performance range

 

[Jeff Peterson]

One minor caveat to Kern's post, the 5.9 mags first appeared in '93.

 

[icetech]

Okay, so If I do the magnum heads I need an intake, rocker set, valve covers and pushrods? But would I have to change from flat tappet camshaft/lifters as well? I'm just trying to get a good idea so I can order everything I need all at once so I don't mess anything up when I go to install it all.

you can use the flat tappet cam, you use AMC lifters which oil through the pushrods

 

[33 IMP]

I am not a small block guy, but......
If you change flat tappet lifters to use Magnum heads, (reqd amc lifters for pushrod oiling)you'd better plan on a new camshaft too, as well as new pushrods.
Cheap and easy? Keep your fast burn 318 heads.
Better? Run the 318s, and wait for speedmaster's black friday sale, and get a pair of lighter, better-flowing heads for cheap.

 

[Kern Dog]

The #302 casting 318 heads are decent for a mild 318 and they bolt right on with no additional changes. Some refer to the 302s as fast burn.
My suggestion of the 5.2-5.9 Magnum heads would probably be best if you were starting g from scratch and were replacing the cam and lifters anyway.
The #308 heads are better flowing but have larger chambers so what you may gain in increased flow, you lose a bit by lowering your compression ratio.

 

[PROSTOCKTOM]

My advice is to stick with what you have for now and spend some time reading and researching this more. Because swapping heads around from LA to Magnum, or the other way around is more involved than your current understanding of the matter. One oils through the rocker shaft and the other oils through the pushrod. I understand how it all works and it still makes my head spin when I think about swapping them around.

I always try to advocate using the KISS method in engine building.

Good Luck!!!
Tom

 

[johnny ga]

i used a set off 302 heads straight bolt on same rocker setup closed chamber will help compression heart shaped chambers