5.9 Magnum block vs 360 LA block....

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1WildRT

1WildRT

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I'm looking at building a small block for a friend.. Currently he has a 340, it needs everything & we're talking about going to a stroker kit.... The one thought I have is using a 5.9/360 roller block rather than the 340.... Let the resto types buy the 340... So, what I'm finding is the 89-92 360 roller blocks are getting harder to find but 5.9's are everywhere....

We already have LA style heads & rockers.. I'm wanting to put a 360 stroker kit in a 5.9 block... About the only thing I keep reading about that's different is the 5.9 has a shorter deck height... So I searched for the stock deck height spec... 5.9 Magnum spec is 9.58, 360 LA spec is 9.59.... .010 difference.... I've decked plenty of blocks .020-.030 so .010 is of no concern.... So I'm here to ask if there's something else I need to be aware of, what's gonna bite me on the butt?

Edit, yeah, I know about the oil passage, got that covered..

I appreciate everyone's input...
 
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Here’s the worst case on pistons that may stick out of the block, you order an expensive custom thickness gasket from Cometic.
 
Later blocks, mounts and oil hole, I’d stay with the 96 and older block. That deck height number might be a typo.
 
If you use headers, and you more than likely will with a stroker, you will probably have to grind on the mid mount bosses on the side of the block for a header tube or 2 to have clearance. Magnum blocks have motor mount ears like an LA 360, but have the mid mount bosses that were used for the motor mounts in trucks/vans/Durango's. Check to see if the stock style roller lifters are up to snuff if you use a hydraulic roller cam. If you're going solid roller, that's a non problem...lol. Morel roller lifters are good in both hydraulic and solid. Push rod oiling to the rockers will solve the no oil hole problem in the decks, or you can get the holes drilled, which won't be cheap.
 
Comp cams and a few other places Mae LA rockers that will work w/pushrod oiling. They (Comp) only come in a 1.5 ratio. The other places which escape my memory right now offer 1.6. Going expensively would be TR or Jesel where a 1.7 is available. But that’s a lot of bread for rockers and it does t included head modification.
 
Seeing as you know about oiling and oil through pushrods about the only thing I can think about/read is the mid mount on the block causing header interference. I’m about to test fit my new tti’s to my magnum block (mopar crate 402) and check for clearance etc after the paint dries. I can report back if you like. I know I probably should have done it before paint but I‘m pretty sure I also remember reading on Magnum swap dot com
( Magnum Swap -your source for Mopar engine swap information. ) that he had no problem with tti headers and the mid mount/grinding etc…. I hope I read right. Lol

i included the link above for magnum swap as there’s also lots of other good info there. Like modifying the magnum oil pan gasket to use it with an LA timing cover etc…. (essentially you have to buy two gasket sets for the pan, the magnum gasket set is nice as it‘s the raised rib silicone type and is known for not leaking, you just have to chop the front bit out and use the LA timing case to pan gasket for that spot And use some silicone where they meet…
 
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4mulas said:
Seeing as you know about oiling and oil through pushrods about the only thing I can think about/read is the mid mount on the block causing header interference. I’m about to test fit my new tti’s to my magnum block (mopar crate 402) and check for clearance etc after the paint dries. I can report back if you like. I know I probably should have done it before paint but I‘m pretty sure I also remember reading on Magnum swap dot com
( Magnum Swap -your source for Mopar engine swap information. ) that he had no problem with tti headers and the mid mount/grinding etc…. I hope I read right. Lol

i included the link above for magnum swap as there’s also lots of other good info there. Like modifying the magnum oil pan gasket to use it with an LA timing cover etc…. (essentially you have to buy two gasket sets for the pan, the magnum gasket set is nice as it‘s the raised rib silicone type and is know for not leaking, you just have to chop the front bit out and use the LA timing case to pan gasket for that spot And use some silicone where they meet…
Click to expand...
That right there answered one of my questions... I was wondering about the oil pan/timing cover cause I will want the early timing cover & obviously will have the Magnum rear main cap... Which I wasn't sure if it was the same as a regular 360 cap or not.... Thanks for that tidbit... I'll be checking out the Magnum Swap link..

I have a line on a 96 5.9 block which from what I've read should have the oil passages... I also have a Bridgeport so drilling a couple oil holes isn't much of an issue...
 
If you’re not married to LA heads might want to consider all magnum solution. The 402 I have came with magnum r/t heads a 108 cl cam, around .510 lift and 234 ish duration and it runs good and pulls hard, sounds great too. I like oil though pushrods and future upgrades like a set of Harland rockers are half the price of LA versions. I like 10 bolt valve covers - no leaks there too
 
Im not sure but the difference in the pan gasket is only the front but. The La car pan has the two wider notches and I think the magnum truck pan did not. The rear bit should the same
 
Biggest advantage to the Magnum engine is the roller cam ( has deeper lifter bosses) and cylinder heads.
Combustion chamber design and ports flow much better than LA heads.
Remember that the Magnum engine was only installed in trucks, thus is low RPM, torque motor. Needs a different cam to wake up.
 
A 360 car pan and any front cover with fuel pump provision will bolt on, one piece gasket fits all the front covers. Just looked at my 95 magnum and headers don’t touch those bosses. I machined the 340 cap to use the rear sump truck pan and one piece gasket, the other is a 360-380 with 318 front cover and accessories.

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gzig5 said:
I don’t think the magnum cam will work with a mechanical fuel pump?
Click to expand...
Bullet, Comp, Crower & Lunati (And likely others) all offer a roller cam with the long snout... Plus Hughes offers a adapter.... Cause Lord knows we all love adapters....
 
Oil pan slight difference , LA pan on a magnum block, there will be some creative sealing on the front corner of the pan, drivers side
 
1WildRT said:
I'm looking at building a small block for a friend.. Currently he has a 340, it needs everything & we're talking about going to a stroker kit.... The one thought I have is using a 5.9/360 roller block rather than the 340.... Let the resto types buy the 340... So, what I'm finding is the 89-92 360 roller blocks are getting harder to find but 5.9's are everywhere....

We already have LA style heads & rockers.. I'm wanting to put a 360 stroker kit in a 5.9 block... About the only thing I keep reading about that's different is the 5.9 has a shorter deck height... So I searched for the stock deck height spec... 5.9 Magnum spec is 9.58, 360 LA spec is 9.59.... .010 difference.... I've decked plenty of blocks .020-.030 so .010 is of no concern.... So I'm here to ask if there's something else I need to be aware of, what's gonna bite me on the butt?

Edit, yeah, I know about the oil passage, got that covered..

I appreciate everyone's input...
Click to expand...
1WildRT said:
That right there answered one of my questions... I was wondering about the oil pan/timing cover cause I will want the early timing cover & obviously will have the Magnum rear main cap... Which I wasn't sure if it was the same as a regular 360 cap or not.... Thanks for that tidbit... I'll be checking out the Magnum Swap link..

I have a line on a 96 5.9 block which from what I've read should have the oil passages... I also have a Bridgeport so drilling a couple oil holes isn't much of an issue...
Click to expand...
Magnum blocks have their own oil filter adapter plate, different from an LA. Do not interchange them. Just use the parts off the donor Magnum block and it is not an issue.

Old style Chrysler starter will usually interfere with the Magnum engine block. Use a mini starter from the Magnum trucks and it is not an issue.

All Magnums, 5.9 and 5.2, use the same oil pan gasket, and you can install the car 360 LA oil pans with a Magnum gasket by using some silicone in the gaps left by the LA pan at the front. I had to do this on mine because a Milodon oil pan was not shaped correctly and the holes for the little nubs on the front LA seal were way off. The Magnum gasket actually fit better, the LA pan has extra "steps" the Magnum gasket will not seal. Just fill those little voids with silicone.

If using a Magnum block with LA oiling holes or drilling the two missing holes on a later Magnum block make sure the camshaft is drilled for LA oiling. Some Magnum spec performance camshafts do not have the long snout on the front requiring an adapter, but some also do not have the LA oil holes drilled in the journals. Not an issue if using pushrod oiling lifters, pushrods, and rocker arms or when using a proper LA camshaft and the holes are present in the journals and the block.

Some of this was already covered and some was not. If I have not forgot any details, the rest is just treating it like an LA.
 
I sure have updated this months ago.... The guy who owns this decided rather than spending whatever it took to build a LA/Magnum he bought a brand new crate 3rd Gen Hemi... And is gathering parts....
 
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