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Magnum Engine Oiling Mods for LA Heads

JedIEG

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I am considering a 360 magnum block as the base for my next engine build simply for the availability in junk yards and roller lifter provisions. I dislike the valve train Chrysler switched to for the magnums and am not interested in running inferior stud rockers. Ideally I would get an early magnum block with the shaft rocker oil drilling but that seems very unlikely to find. Does anyone have experience adding the oil drilling to the block or other mods to make it LA shaft rockers work?

If the stock LA drilling is impractical, I am thinking of adding a short length of the oil drilling to the block, then tapping into the block from the lifter valley at the end of that drill and running a hard line directly to the lifter galley.
 
Inferior rocker studs ?? 1.6 ratio stock. Highest flowing stock heads and most efficient combustion chambers available for the small block Mopar. Do a little more research before you discard the Magnum cylinder head. Many good books available.
 
I agree with everything you said there. Magnum heads have better combustion chambers than previous LA Heads, better flow, better valves and the ratio is a nice bonus. But there is no benefit to durability or performance in a stud mounted rocker. Magnum heads are overlooked as an LA upgrade because of the complexities of the rockers and oiling. I think magnum heads would have been championed as the go-to OE head, had they not switched away from the shaft rocker system.

Ford and GM start OE with studs and then when performance really matters, switch to a shaft mounted system. The magnum family is the only Chrysler engine that uses stud rockers. The Gen I, II & III Hemi, 3.3-3.8 v6, big block, A, LA, Slant 6 all use shafts. I would really love to talk to the chief engineer on the Magnum program and learn why they switched for the magnum. My guess is its cheaper.

That aside, building with a magnum block as a base, I would be looking to put a new set of aluminum heads on the engine. I would rather put the money into the LA version instead of the magnum version because, all else being equal, the shaft rocker system is better.
 
But all else isn't equal. How much power are you trying to accomplish ? Shafts are better but stud rockers have been used by the 10's of millions over the past 60 + years on various brands of heads. They can't be that crappy. Pros, better combustion chambers for more efficient burn, better cam performance with stock 1.6 ratio. Better valve cover sealing due to additional cover bolts. Cons, stud mounted rocker. Possibly come loose ? Pin the stud. = ? Just saying just how bad, unreliable, prone to failure etc... is the stud mounted rocker ? Aftermarket heads are available with shafts. Oiling through hollow pushrods.
 
I am considering a 360 magnum block as the base for my next engine build simply for the availability in junk yards and roller lifter provisions. I dislike the valve train Chrysler switched to for the magnums and am not interested in running inferior stud rockers. Ideally I would get an early magnum block with the shaft rocker oil drilling but that seems very unlikely to find. Does anyone have experience adding the oil drilling to the block or other mods to make it LA shaft rockers work?

If the stock LA drilling is impractical, I am thinking of adding a short length of the oil drilling to the block, then tapping into the block from the lifter valley at the end of that drill and running a hard line directly to the lifter galley.
No need for oiling modifications if you use the correct rocker arms for this swap. Just choose your heads and get PRW or similar rocker arms that allow oil to run through the Magnum roller lifters, up through hollow pushrods, and into the rocker arm for proper oiling. All parts can be sourced separately or you can contact B3 racing for pricing.
This allows you to stay with typical LA style heads and rocker shafts bolted directly to a Magnum block with no extra machining or modifications needed.
 
But all else isn't equal.
You got me thinking about that more. Where I am coming from is looking at Edelbrock RPM and Indy LA-X and MA-X heads. The Indy heads are exactly the same casting with either the magnum or LA machining done. So for that, all things are equal except the choice of valvetrain. I assumed this was the same for the Edelbrocks, because that seems the most cost effective way to develop those products but they are different castings which is a little baffling to me. That does confound the decision on what to use since their magnum castings have a better port and appear to have the magnum combustion chamber.
get PRW or similar rocker arms
That is an interesting option. I really like the big block bushed rockers, but it looks like they are not offering that for the small block. I would be worried about running needle bearings on a street engine and I am use to dealing with bushed rockers.
 
You got me thinking about that more. Where I am coming from is looking at Edelbrock RPM and Indy LA-X and MA-X heads. The Indy heads are exactly the same casting with either the magnum or LA machining done. So for that, all things are equal except the choice of valvetrain. I assumed this was the same for the Edelbrocks, because that seems the most cost effective way to develop those products but they are different castings which is a little baffling to me. That does confound the decision on what to use since their magnum castings have a better port and appear to have the magnum combustion chamber.

That is an interesting option. I really like the big block bushed rockers, but it looks like they are not offering that for the small block. I would be worried about running needle bearings on a street engine and I am use to dealing with bushed rockers.

Are LA-X and MA-X heads currently available? Unless someone still has them in stock, I thought they were not currently being produced.

PRW does have alloy rocker arms for small blocks that are basically copies of the Comp Ultra Pro Magnum rocker arms for LA Mopars. They are both bushed, and both allow pushrod oiling for perfect application on Magnum blocks with LA heads and no extra drilling. Speedmaster and couple other places sell the same type of copies. They are all very similar.

The Edelbrock Magnum head has stud mounts specifically allowing the use of less expensive Chevy small block rocker arms and pushrod oiling.

You did not list your horsepower goals, budget, or intended use, but any of these parts will work fine up to the horsepower limits of the factory cast iron block itself. So if you are more comfortable with the LA rocker arm system, just build it with LA style heads of your choice, which allows for more LA intake choices, and then use one these LA style rocker arms that allow pushrod oiling.

Sorry for the long post. Just trying to be clear as there is a lot of misinformation about Magnum blocks as a base for a build. Many have been done very well.
 
I am currently working to transitioning the car to my daily drive. I want a good street engine but also fun to drive spirited on winding roads and attend a track day or autocross with zero worry of hurting the motor. Transient response, mid range torque, and durability are key to me over peak horsepower or 1/4 et. It is a street car so crappy idle and poor vacuum is not acceptable. Because I want good handling, I would like aluminum heads for the weight as well as performance, but $1500 for a pair is about as much as I want to spend. Engine cost target would be around $3500 and I do all work except the specialIty machining. I would be benchmarking the 392 Hemi crate engine as a performance target. 450-500ft-lb&hp, but the actual torque curve matters way more. I am probably looking at a 4" stroke and hence the reason for wanting the 360 mains, and roller cam provisions would help get the flow at lower durations to meet idle quality. I am biased towards fully pressurized, bushed, shaft mounted rockers for their simplisity, durability and stability under transient conditions.
 
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