Sm Blk heads

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ir3333

ir3333

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Any real world tests comparing LA heads to Magnum heads.
Despite what a lot say I have custom cam grinders tell me the LA heads are superior.
...your thoughts / experience?
 
shaft rocker system is more stable on LA head but can be limiting. LA heads I believe are open chambers. As for flow mine are pretty serious x heads and flow 278-284ish. With the pushrod pinch still there. Don’t know what magnums are capable of.
 
Being a head porter the first thing I do when I am near a set of heads of heads with the valves out is run my finger from the intake valve and feel the short side ramp. My Friend has a set of magnum heads sitting there that he ported for his son and man they are way nicer than an X or J head. After market I plan to stick to the LA style head.
 
furrystump said:
shaft rocker system is more stable on LA head but can be limiting. LA heads I believe are open chambers. As for flow mine are pretty serious x heads and flow 278-284ish. With the pushrod pinch still there. Don’t know what magnums are capable of.
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Does a camgrinder really care about shaft or stud rockers systems especially on an OE head? J.Rob
 
O.K. in stock form which do you consider superior in both flow and function?
 
ir3333 said:
O.K. in stock form which do you consider superior in both flow and function?
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Easily Magnum for potential. Better chamber, Deeper bowls, less carving on the guide boss (intake), exhaust runner/bowl is vastly superior to LA. J.Rob
 
I've always heard that OEM Magnums flow a bit better that OEM LA heads while racing IHRA Stock in the crate motor classes. The 360/300hp Magnum was "refactored" 5hp more than the 360/300hp Commando LA combo. Here is a "rough" chart, but the quality of porting and valve jobs, as well as different flow benches, are a factor. They don't mention valve sizes in most cases, but the "stock" 894 and 915J are likely 2.02". Personally, I preferred the LA combo due to familiarity and parts availability.

I was also told that there were also 2 different OEM Magnum castings, with one being better than the other. But I don't know more than that.

Mopar LA Cylinder Head Comparison
 
TX guys,all good info but this is for stock heads as they are cast...no porting
 
ir3333 said:
Any real world tests comparing LA heads to Magnum heads.
Despite what a lot say I have custom cam grinders tell me the LA heads are superior.
...your thoughts / experience?
Click to expand...
Closed Chamber Heads for the WIN! My Gawd Magnum.............lol
 
Which LA heads? X/J types? Smaller 675 heads for 318's? Swirl ports? Wha t is of importance?
  • The rocker system differences have been pointed out.
  • Are you interested in compression ratio? Magnums are easier to us to get CR up.
  • Interested in getting quench effect easily? Magnums are closed chamber types, so better to start with.
  • Is flow the parameter of interest? This mentions some flow numbers for the Magnums:
 
ir3333 said:
Any real world tests comparing LA heads to Magnum heads.
Despite what a lot say I have custom cam grinders tell me the LA heads are superior.
...your thoughts / experience?
Click to expand...

My thoughts
I can see how a camgrinder wants to see as much of his lobes motion getting to the valve instad of getting lost in the shape of flexing valvetrain and thats where a shaftmount system realy shines. anyone that has been paying attention while installing rocker stud girdles on a smallblockchevy with any kind of springpreasure knows what im talking about(yeah i know they are available for magnums aswell but not nearly as comon)
The magnum chambers are supperior,ports are probably better aswell.
From a hotroding perspective there is not nearly as many intakemanifolds to chose from for a magnum and that is a limitation depending on what you are doing.
 
LA rocker shafts for me. Never did like magnum heads! If need more power I would just get aftermarket LA style only.
 
When the magnum first came out it was deemed as the "be all to end all" but opinion is divided now.
All good info guys.
Would be nice to see a sm blk dyno with each head for a stock performance comparison
 
I never heard that the magnum head was it and I will be off. I think the head has certain benefits over in LA. In the end, it really doesn’t matter what you have on top. It matters how you use it.
I never heard that the magnum head was it and will be all. I think the head has certain benefits over in LA. In the end, it really doesn’t matter what you have on top. It matters how you use it.

The cam grinder probably wants to know due to how the ports flow. As well as the rocker ratio being used for a specific lift. The more he knows about the engine, the better the cam can be.
 
I'd take a factory 2.02 valve x or j over a factory 1.94 valve magnum head.Small int valve J head to larger magnum int valve head... that's a no brainer=magnum
 
My flow bench showed only about a 10cfm edge over the LA heads, stock to stock.
LA's are king in the realm of stability, the Magnums have a nicer short side radius and a nicer bowl.
The RHS versions are even nicer in this area.
Conversely, the LA Short Side Radius' are plagued with that dumb angle next to the long wall side of the port that is very close to water. The opposite is true on the Mag, in fact, that funky cavity on the Turn Wall is better for flow but, unnecessarily big in that area, IMO.
Magnum Exh ports are much better than the LA's with the exception of the later LA #596 exh.
The push rod pinch on both designs have their own problems.
Magnum chambers are much more efficient than the LA's. The fact that a Mag head motor don't need as much Ign lead bares this out.
I did a mild set of RHS's that sent a fairly mild 400+" SB that ran 10.33 @ 131 with only 30* of timing in it, on it's first outing. It later went 10.14 @ 133. That's the chamber at work.
The main problem I have with the Mag chambers is, they have much more Int valve shrouding than the LA's, which is a problem with large valves. There is just no way getting around it.
Both head are heavy.
I do not intend to toss the LA heads under the bus.. They have made car's haul for years, including mine.

The LA's hold their edge in valve train stability. Very important in high rpm/high spring pressure situations. Shaft stands are too high for optimum geometry. (.050)
LA chambers do not limit valve size but, while the Short Side Radius being so close to water, you still have some limitations.
The Mag head sports a very good chamber but, is limited in valve size. Funky port, but has good valve coefficient numbers. Terrible valvetrain arrangement, not stable. Too much deflection.
Not racing? none of this matters..
 
Screenshot_20171212-101519.png

Here a 300 hp magnum dyno vs a top end swap. In stock form the magnum head definitely has the advantage. Headers on a 4bbl LA ain't gonna make 320 hp.

Screenshot_20171212-084647.png


Here the 380hp magnum create engine and a cam really wakes up these heads.

As for quench you can build an LA with it, with the right pistons just a little more involved.

Always heard LA heads have the advantage ported but never seen a shoot out between the two.

But really if starting from scratch start with at least EQ heads.
 
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