360, LA360, or Magnum 360?

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ive always had la's...they've been good to me,but i got a smokin deal on a warmed over 5.9 mag. and had to try it out. lxguy's site has been an excellent tool for me thus far...im not running yet,but hope to have it mounted to its k member and ready to fire by the end of this weekend.

thanks for the magnumswap.com extra helpful!

the only bumps ive encountered were with trying to use a 904 flite. b&m discontinued theyre 904/magnum flexplate and mopar performance has discontinued theyre magnum weight and template kit (mine was worthless anyway with no template...thanks ma). i did find out that 97-up has the correcly balanced flexplate to use with my 318 converter...just have to oblong one hole. $20 at my local junkyard.the only other concern there is the converter bolt holes are a lil loose around the bolts,so there maybe a problem with it being off center (i'll let ya know this weekend).

am i the only one thats been paying ALOT more for mini starters,not knowing that a 97 model o'reiley's starter is IDENTICAL for 60some bucks? i love learnin this stuff!!
 
if you can i'd do an compression test on the 73 if thats the one you choose, powerwise the 5.9L has a higher net power rating than LA 360, but i imagine with same carb, intake and exhaust they would be pretty close
 
273 said:
if you can i'd do an compression test on the 73 if thats the one you choose, powerwise the 5.9L has a higher net power rating than LA 360, but i imagine with same carb, intake and exhaust they would be pretty close
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Thanks, 273. This is what I was hoping to hear.
Is true that the main difference is the improved head design on the Magnum? If so, since most of these are cracked and need to be replaced anyway, sounds like a moot point.

I like the idea of having the right "year" motor in my car (even if it wasn't an available option that year). I can imagine running some aluminum heads and a hot cam down the road.

BTW, how does the early 360 compare to the lower compression/cast crank late '72 -'73 340 motors? Do they share any internals? How many bolts on the main bearings?
 
Only differance on the early 360 is they had a flat top piston, not dished. All 360s were cast crank, and two bolt mains.
 
replicaracer43 said:
Only differance on the early 360 is they had a flat top piston, not dished. All 360s were cast crank, and two bolt mains.
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Cool... good info.

Is it a safe assumption that they might have a higher compression ratio?

The two-bolt mains sound like the weak link with these motors...but this is the same in the Magnums anyway, right?

Thanks again!
Mike
 
They may have been slightly higher compression. And no, the weak link is probally the bolts, not the caps, they are much larger than the typical chevy junk, they need 4 bolts to hold those tiny caps on!
 
if you place mopar 2 bolt main cap and a chevy 2 bolt main cap next to each other, the mopar unit dwarfs the chevy unit..
 
replicaracer43 said:
They may have been slightly higher compression. And no, the weak link is probally the bolts, not the caps, they are much larger than the typical chevy junk, they need 4 bolts to hold those tiny caps on!
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mopardude318 said:
if you place mopar 2 bolt main cap and a chevy 2 bolt main cap next to each other, the mopar unit dwarfs the chevy unit..
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:glasses7:
Niice.
 
I was going to build my early 360 but got a killer deal on a 91 with less than 4k on rebuild. have to say i like the way the roller cam revs. Even with just the rebuild it has plenty of daily driver power I've walked away from a few wanna be racers already lol. Some of the parts are off my old 360 so it don't look as new as it is.
 

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mwls73duster360 said:
I was going to build my early 360 but got a killer deal on a 91 with less than 4k on rebuild. have to say i like the way the roller cam revs. Even with just the rebuild it has plenty of daily driver power I've walked away from a few wanna be racers already lol. Some of the parts are off my old 360 so it don't look as new as it is.
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Good feedback here! Thanks!

Any guesses as to why it might rev better? Does it have a lighter crank or lighter pistons?

How many RPM can you turn on the stock bottom end on Magnums or LAs...is there a big difference here?
 
Well one my old motor was tired lol. But this is my first roller cam. If I'm correct rollers get lower RPMs quicker but you can't take they as high safely as a solid? I use to run myother mopars up to 7000 with solid lol only broke a motor once. Threw a main bearing in my charger se 400 seeing if it would max out the 150 Speedo it passed the mark then killed over lol I'm dumb occasionally but that's how we learn.
 
Idk the down side except they cost more lol I'm new to rollers and the comparison i made above is wrong lol found this short bit on why they say to go roller. Roller*lifters can be re-used over and over again. The ramp speed is lightning fast compared to a flat tappet cam, and the lobe profile is awesome which only equates to making more power. You get a better idle, more manifold vacuum and better throttle response with roller cams.
 
Basically the bottom ends are the same, but the magnums have a lighter piston I think, plus they have thinner rings, reduces drag a little. The stock shortblock would be mostly the same as far as rpm goes, but the valvetrain would be the limiting factor. I think stock magnum would be ok to 5800 or so.. But with good springs, cam, rockers ect, the sky is the limit.
 
^--- the bottom end of my Magnum feels light and frisky. Better and newer metallurgy makes this happen, go Magnum.
 
The main advantage in the magnum short block is factory hydraulic roller lifters but the stock cam itself sucks, head wise depends who's flow numbers you go by it seems the magnum have a slight avantage over LA's but ported LA's seem to win, Factory and aftermarket Magnums heads will work on an LA block with the right hardware. 73 360 should have thicker cylinders and J Heads.
 
Thanks again, guys....

So here's one question that has been lingering for me.

Assuming you find a clean, documented Magnum...but the heads are cracked.
Does this mean the heads are automatically garbage? Assuming they don't leak, can you still run them? It sounds like people get huge mileage out of the Magnum motors so when do cracks become a problem?

BTW, I can't thank all of you guys enough. This forum is amongst the best I have seen. You guys are generous with info....and have spectacular taste in cars too! :D

I'm checking out the '73 LA 360 tomorrow...but if it's a piece, I'm back to looking at Magnums. :)
 
The early 90s are still la but roller cam to me its a good middle ground get the roller but all bolt on la parts
 
mischiefdart said:
Biggest drawback of the magnum is the heads have a tendency to crack. I would look for a late eighties to '91 pickup or van with the roller cam la motor. I am thinking about picking up a wrecked low miles '90 3500 van and installing the 360 with the fuel injection in on of my darts.
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I bought a complete '90 vintage 360 w/64K miles for $200 when United Way junked the van because it was old...nothing wrong with it, had plenty of life left in it. My buddy bought the trans for $85 and sold it for $450. What a waste- but profitable for me & Jason! Using the 360 in my '85 AHB Gran Fury
 
V-100 said:
I bought a complete '90 vintage 360 w/64K miles for $200 when United Way junked the van because it was old...nothing wrong with it, had plenty of life left in it. ...
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Good find! Plus you can do smoke shows for charity! :D
 
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