LA 360 or Magnum 5.9

[Texas charger 73]

I've got a 1973 dodge charger with a tired number matching 318. Running a built 904. LA motors are getting harder and harder to find, but magnums are readily available. I want something around 320-350 hp. I hear it's alot easier to get with magnum motors. I know factory heads on mags are bad and the cam will need to be changed to a long snout or use a kit to create a centric on cam to run mechanical fuel Pump. Who has done this build or swap. Is it pretty simple and everything bolt up or should I just keep. Looking for a LA 360 to build.

 

[BeepBeepRR]

You can go to DakotaRT.com and poke around there. Those guys are magnum guys and know what makes power on them.

 

[Greg Ducato]

There are good , new, cast heads available for the Magnum in either Magnum or LA intake bolt patterns. Hughes will have a good variety of cams for this set up. The Magnum engine makes very good power per dollar and is super cheap and easy to get into a good builder core.

 

[aeon280]

Go with a Magnum simply for the modernization purposes. Less leaking, roller cam, timing chain tensioner. If you can source a low mileage one you probably wont even need a rebuild. check out these locations here in North Texas.

http://www.autorecyclinglewisville.com/ - independently owned, usually has really good prices. bought a low milage hyundai 4 cylinder form him for 300 a few yrs back.

https://www.stonesautomotive.com/- I was there about a 3 months ago and they had several dakota's and a couple of late 90,s early 00 rams on the lot so they may have some magnums on hand.

If you get a magnum or LA and want heads I have a set of built Aluminum Magnums I need to get rid of. I had them built for my 340 project I never used because the new project I bought already had aluminum eddys and a 340. They have 2.02 int 1.625 ex. ferrea valves, LS6 beehive springs, 1.6 roller comp magnum roller rockers minor port and polish 58cc chambers. I have about 2500 in the heads with machine work and parts. Looking to move them out for $2000 and will include a new Crosswind polished intake, black aluminum mopar valve covers(with reusable gaskets), and set of MR gasket MLS .040 GASKETs. I also have a set of manley oil through hardened pushrods but they might not work on the Magnum roller motor because of the length. 7.625 I believe.

 

[74Sebring]

I rebuilt the LA 360 in my Satellite and I'm pretty sure I'm in your horsepower neighborhood. That being said, I think you're probably better off with a magnum engine. That puts you much closer to your power goals right from the start than using an LA. You could probably find one that was already rated around 300 HP in stock trim. The LA is only rated around 265 HP. I don't know for sure what, if any, problems the transmission mating to the magnum block may bring up. I would try and find out what hurdles are involved with transmission to block and the motor mounts and trans mount. Then dig into firewall and hood clearance as well as K member and oil pan issues. Hopefully, there are none. You'll have you hands full with the computer system mating up with the old wiring harness. I know a bit about that as i rewired my entire car. I thought that would never end. Either way, not trying to sound like an old sage. I'm not. My two cents says, Magnum = more power faster, LA = maybe less hassle overall. If you can't find an LA in Texas, take a ride north. We've got plenty in Kansas. Good luck!

 

[Texas charger 73]

I will be going carbureted magnum not fuel. Injection. I been reading. Up. And seeing what is different in the motors

 

[wyrmrider]

360 Magnum and EFI
you will never go back to carb

 

[rumblefish360]

You can go to DakotaRT.com and poke around there. Those guys are magnum guys and know what makes power on them.

Same thing that makes power on LA’s unless your keeping the factory fuel injection and computer.
;)
Follow the 3 C’s of engine building in a balanced fashion. Cam, carburetor, compression. (AKA, good engine combo.) Followed by the last 2 C’s. Converter and cogs. (Part of the combo!)

Stock OE Magnum engines are lift limited. Your not getting a .575 lift cam in there. MP’s create engine, the 380/360 used a lift under .520. I’m not sure how far you can go.

 

[wyrmrider]

The stock or Direct Connection stock type Magnum Heads (which I have on my 92 flow better than mildly ported LA heads-
As the poster above said if you want lift you have to change the rockers and rocker studs etc
But then if you want lots of lift with a shaft rocker you have to relocate the shaft if you want it to live. longer valves, taller springs etc
best going to aftermarket heads if legal for U-- or NEW HEMI (copy of Porsche heads- wish they had made them for the LA block, the lifter angle was designed for Hemi Heads)

 

[Texas charger 73]

Same thing that makes power on LA’s unless your keeping the factory fuel injection and computer.
;)
Follow the 3 C’s of engine building in a balanced fashion. Cam, carburetor, compression. (AKA, good engine combo.) Followed by the last 2 C’s. Converter and cogs. (Part of the combo!)

Stock OE Magnum engines are lift limited. Your not getting a .575 lift cam in there. MP’s create engine, the 380/360 used a lift under .520. I’m not sure how far you can go.

I'm. Sure. Like a .484 cam would be suffice.

 

[rumblefish360]

Just remember the rocker ratio changed.

.484 / 1.5 = .3226
.3226 x 1.6 = .516 new lift in theory. Doesn’t include loss to do a few factors, of course.

IMO, that ought to be good to go.

 

[74Sebring]

For my LA I used the following,
Comp Cams 20-223-3 lift .477/.480 duration 268/280
Speed Pro flat top w/ 5 cc valve relief
Stock crank and rods deck height pretty much 0
Headman Headers
Weiand Action+ intake
Stock heads unchanged J code
Carter Thermoquad 850 cfm

Sucks the gas but it runs pretty strong

 

[Texas charger 73]

I wish I could find an LA motor. I know a magnum would be more updated and logical but a hole lot more expensive. For now my plan is a magnum unless I stumble on a LA 360 by chance.

 

[wyrmrider]

Magnum more expensive? how is that?

 

[74Sebring]

I could check a couple of places up here, if you would be able to pick up if anything is available? I don't know if you're stuck checking locally only.

 

[Texas charger 73]

Magnum more expensive? how is that?

LA cams, heads and intake don't cost near as much. Just a good magnum can is $250-300. Good Eddy intake is $300. EQ heads over a $1000.

 

[wyrmrider]

regrind the magnum roller
Edelbrock heads are about the same for either
rebuilt heads cost the same
Idk about manifolds

 

[rumblefish360]

regrind the magnum roller
Edelbrock heads are about the same for either
rebuilt heads cost the same
Idk about manifolds

At what? $100 for shipping round trip? And packaging material as well?
Might as well get a nice new, brand new cam.
Magnum heads cost more.
True on rebuilt heads! The way I see it, why bother with a stock head unless it is stock performance? Or very close.
Magnum intakes are more money.

Same headers

But i’d is still do a Magnum!

 

[Bobzilla]

With the low horsepower goals, you can get a running Magnum 360, don't even remove the heads, just upgrade the cam and valve springs staying within the lift limits, keep stock lifters, put your LA fuel pump eccentric, front cover, and pulleys from your LA 318, the chinese air gap manifold because it has the correct LA thermostat size and position, and you end at your goals very cheap. There is still small stuff like motor mounts and flex plate, but those are easy answers. The easy alternative, if you are stuck on wanting an LA, is to just do a low buck rebuild on your 318 since you already know it's a good core. Nothing wrong with a 318 in that power range. I would do the Magnum though, if you don't care about the original block staying in the car.

 

[EccentricMagpies]

I went with magnum heads (among cam/intake) on my LA build. 411 HP