Magnum head and exh manifold ID

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racingsnake440

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I've found a 318 magnum powered van in a junkyard and wanted to check a couple of things:

do the 318 and 360 magnums use the same valve sizes and ports?

how much better are the mopar performance magnum r/t heads than the stock production ones?

i've read that some magnum exhaust manifolds are more desirable than others - how can i tell if this van has the good ones?

do all magnum powered vehicles use basically the same exhaust manifolds or are some a better fit in a bodies than others?

how can i tell what year the van is?

thanks
 
2 types of magnum heads 1 for 318's the 302 casting no. and a different head 308 casting no. for the 360 head. I beleive the 318 head is 188 in. and 165 ex, valve size the 360 head is 192 in. and 165 ex valves. The 360 head has 360 size ports and the 318 has has smaller ports and a slightly smaller combustion chamber. Overall the 360 magnum head is excellent, but you will also need new lifters and push rods with a new intake manifold.
Exhaust maniflods were the same 318/360 although I beleive the 98 up manifold's were slightly better.
Van year - Usually the sticker on the drivers door says prodution date.
 
Actually my understanding of them is that the 318 and 360 magnums use the same heads and manifolds. Check it out for your self here --->http://www.mopar.com/muscle/index.html You'll have to look in their catalog but you will see they offer the heads as
P5007140 *Cast Iron R/T Head — 1.92" Intake, 1 5/8" Exhaust (5.2L/5.9L Truck Magnum/Jeep® Engines) $443.00 Click here
P5007141 *Cast Iron R/T Head — 2.02" Intake, 1 5/8" Exhaust (5.2L/5.9L Truck Magnum/Jeep® Engines) $508.00 Click here
P5007145 *Magnum R/T Cast Iron Head Assembly -- 1.92" Int./1.625" Ex. (5.2L/5.9L Magnum/Jeep® Engines) $783.00 Click here
notice they are for either 5.2 or 5.9. Same same.
 
Yes that is true for the RT head, I was listing info for the stock 318/302 or 360/308 head. The heads are different for the 2 engines, while the exhaust manifolds are the same for any given year. Well I better put as far as I know. I have been known to have the odd brain fart!
 
The 318/302 and the 360/308s are not magnum heads they are premagnum heads. The magnum heads didn't come out until 92 and later, and they take different intake manifolds and rocker gear. The eariler heads are hard to adapt to the magnum engines due to oiling considerations and rocker gear.





BJR Racing
 
It's the 92/93 magnum exhaust manifolds that flow better than the latter ones. Plus all have the outlets in the same place and I don not how easy it is to make them work in an A-body.
 
According to the "How to build big inch Mopar small blocks" book 1992-2003
magnum heads can replace the 1967-1992 LA heads. The increase in airflow
can gain 20 to 50 HP depending on the combination. There are 2 major differences between these two: the magnum rockers oil through the pushrods
whereas the LA oils through the block,around two headbolts, and up to the rocker shaft. The second difference is that the Magnum intake manifold bolts to the head vertically and not at a 90 degree angle like the LA heads. 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.
I have been studying this combination as a temporary replacement for my tired old HP273 in my 66 Dart. I found a good set of heads for $20 and a mid 80's junked out Chrysler 5th Avenue with a good running 318 LA for the cost of towing and labor to pull the motor out. I thought I'd give it a try. By the way, If you want to install the Magnum in an earlier a body v8 car the motor mount tabs are on the block for both new and old applications and the transmission/bellhousing bolt circle is the same. Boy I better get to work b/4 I'm late. Later and good luck!
toolmanmike
 
A friend of mine dropped by the other day and I showed him a pair of magnum heads I got off of a 5.9 (360). I asked the same question to him about the 318/360 magnums. He is a Chrysler tech at a local dealership. He said they are the same head. 302 and 308 are numbers on all the swirl port heads from approx. 86 to mid 92. I have looked at a lot of trucks and vans at the JY and I have seen the magnums in 92 vans and swirl ports on 92 trucks. According to the new Mopar Performance Manuel, the 5.2 magnums (318 ) have a NH on the head casting under the valve cover and the 5.9 magnums (360) have a CF. Now, I have seen some of the early 5.2/5.9 magnum heads have the numbers 302 on the intake runners, none with a 308. I am not saying they don't exist, I just haven't seen any on a magnum engine. I have seen heads with the letters NH on 5.2 and 5.9 engines, but never a CF. Most of the heads have numbers and very few have the letters. None of the numbers I have seen match any of the numbers in the MP Manuel. So far every magnum I have pulled an intake and head on, looks just alike no matter what the numbers or letters. My conclusion is that the 5.2 and the 5.9 magnum heads really are the same casting....valves, ports, manifolds, and chambers. Someone show us some pics of the 5.2 and 5.9 with the intakes, valves, and chambers compaired to each other.
 
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
Click to expand...

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.
 
And a correction to you DGC333, you can use LA "Aluminum" valve covers on a magnum head. You cannot use a stock steel valve cover from an LA because they won't clear the rockers. Other than that all your other statements are dead on. All I need for my conversion from my stock 360 heads to the magnum heads on the floor in my garage, is an intake. :evil:
 
Are you sure about that?

I have a set of stock LA covers and a set of stock magnum covers. The magnums have a full length baffle inside that reduces the inside volume of the valve cover by quite a bit. I do know for sure most roller rockers will interfer with the baffle on a stock magnum cover. I would think the LA cover would be roomier and have lees issues with interference with the rocker gear.

The only valve covers I have tried are the cast aluminum MP covers you see in pics of my engine and a set of Moroso chrome steel covers which also fit just fine.
 
I just went out and tried a set from a stock 318 and a set from a stock 360 and they wont fit, they might if you put a spacer under them, 1/4" would do I think, but not with out. I suppose u could strip the baffle out and stuff but then you would get oil finding it's way out I am sure. But plain an simple the LA aluminum covers do clear and clear it well. I do have a set of them also and have checked that fit and it was perfect.
 
dgc333 - what octane gas do you use? have you run your car down the strip at all - if so what does it run?
 
For the "KISS" principle, why bother adapting magnum heads to an earlier block? For what most folks will do, just get the whole motor and gain a nice roller cam in the bargain. Time, money and frustration saved in the majority of situations
 
racingsnake440 said:
dgc333 - what octane gas do you use? have you run your car down the strip at all - if so what does it run?
Click to expand...

The car runs fine on 89 octane but since a fill with 93 is only an addtional $2 I usually run 93.

I have not run it down the strip but I have one of those accelerometer devices that gives you 1/4 miles times and speeds. I have an issue right now with the car launching (a lot of wheel hop resulting) and under hard acceleration the the clutch hangs up (hope the sub frame connectors I plan to install this week end will help). Also since trying to make hard shifts I have discovered the shifter I am using gets balky so I have had to shift slowly.

Anyway, with those issues the car runs low 14's at over 100 mph. Based on the trap speed if I can get the wheel hop, clutch issues and shifter sorted out the car should easily run low 13's.
 
6t8 Dart said:
For the "KISS" principle, why bother adapting magnum heads to an earlier block? For what most folks will do, just get the whole motor and gain a nice roller cam in the bargain. Time, money and frustration saved in the majority of situations
Click to expand...

It's a simple and easy way to to get a significant increase in power form a LA motor.

Using a complete magnum motor requires swaping a lot of parts before you can drop it in a older chassis. Certainly not hard but I would contend that on the "KISS" scale it would be equivalent to installing magnum heads on a LA motor. Plus the cost of entry will be much more to procure a magnum motor than a LA motor.
 
Keeping it simple is using the 360 engine I have IN the car, and swapping a set of 360 mag heads I got free, will have to aquire an intake but cost wise the cost of an intake and some gaskets to get a boost of compression and newer port and head design to make more power, sounds a hell of alot cheaper than trying to track down a running and built 360 magnum and then trying to get it in to the car.
 
The few 360 magnums I have seen in the JY seem to have a problem with the rubber in the balancer discentigrating. What's up with that? When the rubber goes away, the vibration ruins the bearings and with the amount of slop in moving the crank back and foreth in the block, I worry that the crank and/or the block are junk.
 
Any engine you get from the junk yard that you can't here run has to be considered a core for rebuilding. The balancer slipping will certainly cause vibration and will ruin the bearings. Can't imagine how anyone could drive a vehicle that was bad enough to damage the block and the crank can always be turned down for a standard undersize bearing.
 
Apparently some people here have never swapped a Magnum engine into an older car before.
They use the same motor mount bossing and bellhousing bolt pattern as any LA engine..
The front accessories, timing cover, PS pump, water pump and alternator brackets from the older blocks will bolt on.
IMO, the serpentine set-up and the high output alternator would be a BLESSING to an older MoPar.
Adapting the power steering pump high pressure line to the older box is a cinch and who wouldn't like the more efficient A/C compressor installed onto an older conversion?
The only real difference is with the 360 Magnum's balance and that's a minor issue, in reality.

I'm currently working with another 360 Magnum conversion to an older vehicle, which will again employ all the nicities that a Magnum has to offer, along with the stock fuel and emmisions management of a computer-controlled engine.

All in all, a late model conversion into an early body is only as hard as you make it. Just diving in never did more than ruin a few parts and cause a few extra $$ to be spent.
Both are replaceable.

Mark.
 
Mark Nixon said:
IMO, the serpentine set-up and the high output alternator would be a BLESSING to an older MoPar.
Mark.
Click to expand...
That reminds me, is it possible to swap a magnum serpentine system onto an LA block? If not, why not? I would like to make mine serpentine but can't spend the $300= for the march kit. Thanks

-Alex
 
magnum motors have a reverse rotation water pump on them also.
 
Orionsax7 said:
That reminds me, is it possible to swap a magnum serpentine system onto an LA block?....
Click to expand...

Not without the Magnum heads.
There are extra bolt holes in the ends of the heads to allow the power steering pump and alternator to bolt up.
As long as you use the heads, timing cover, water pump, fan, pullies, A/C pump (if desired) and alternator it'll all bolt up.
You can use a flat tappet cam, but you need to use an AMC lifter and custom length pushrods so that the rockers get oil.

It really is easier (read: CHEAPER) to get a Magnum engine and start from there.

If you like the older appearance, the valve covers from an LA engine will bolt to a Magnum head, but, I believe, a spacer needs to be made to keep the stock covers from being hit by the rocker gear.
I'm told aftermarket aluminum covers will clear.

There's a fellow on the Yuppie-Snob Site, Moparts, who also loans a tool to convert Magnum heads over to use an LA intake.
Or maybe it's the other way around? I forget.

By the time you're done, it could LOOK like an LA with the serpentine stuff on it, but is it worth the hassles?

Mark.
 
Mark Nixon said:
There's a fellow on the Yuppie-Snob Site, Moparts, who also loans a tool to convert Magnum heads over to use an LA intake.
Or maybe it's the other way around? I forget.

Mark.
Click to expand...


Mark, it's not good for you to hold things in like that... ;)
 
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