LA Mopar heads on a Magnum Block. Can it be done?

Magnum Mopar small blocks are way more common than their older LA brothers, but aftermarket support just isn't there. Follow along as we bring together the best of both worlds and use a Magnum short block with an LA top end to make the ultimate modern day Small Block Mopar.
Cley

[@craighansen7594]

I've considered the same combination to replace the 340 in my 1970 Dart Swinger. The 340 runs great and has had a good amount of abuse. I really don't want to hurt it. A magnum 360 would be interesting and if it disassembled itself it could be easily replaced.

[@Mynextproject_74]

I agree. That is why I hope this will be good with a stock bottom end. Then if it fails, I won't be down for too long!

[@rong4189]

Good job, good video. I guess the early Magnum blocks were drilled for top end oiling but those must be tough to find!

[@Mynextproject_74]

Yeah, the last couple years of LA 360s were roller cammed with the better blocks and the first couple years of Magnum 360 blocks will do the rocker shaft oiling. And that's not set in stone either. I'm glad I could make this work.

[@jmflournoy386]

tough to drill with a hand drill I used to have a jig or did them in the vertical mill

[@gregtough9055]

That should be a great combo!

[@Mynextproject_74]

I sure hope so!

[@tonytavolieri1663]

Good job on the engine!! Can't wait to see it run!

[@Mynextproject_74]

Ah, me too! It's been a long time coming!

[@aaronbarnes8938]

A few things I have noticed I would have left the holes in the rocker shafts for extra oil to be on hand for dry starts. Also Those heads come with the wrong spring size for the rocker arms and a beehive is the correct fix. if you mark the adjuster and the main body of the rockers oiling holes and line them up when you adjust them really helps with the oiling of them. Great job on your setup.

[@junkyard_D]

Cool build. I am interested to hear it fire up and see how it performs. 👍

[@Mynextproject_74]

I'll share all that as it happens. It will go on a run stand first. My only concern is the 9 to 1 Compression. It may want more, but we will see!

[@robertwest3093]

I just subscribed! Nothing I like better than going fast on the cheap.

[@Mynextproject_74]

Thanks! I'll keep working on it!

[@shadvan9494]

you will have fun with that cam. I ran that cam in a 396 big block chevy and it was awesome. make about 435 HP and 495 FTLB with factory oval port heads, headers, and an Edelbrock Torker II-O intake. it would have been better with a performer RPM intake, but it would not fit under my hood.

[@fastbackcuda]

Can’t wait to see how this turns out. I am putting together the same set up with a 360 Magnum stroked to 408. Edlebrock LA heads with same oiling system you are running. Only difference is I am running a B3 geometry correction kit for the rocker shafts. Lower end is complete and I’m assembling top end now. When do you plan on posting your motor on the run stand? 👍

[@Mynextproject_74]

It's on the stand right now. Either this Sunday or next Sunday if all goes well.

[@318willrun]

Should be a stout engine!

[@Mynextproject_74]

I'm counting on it! Been a long time collecting parts!

[@lynnrunningdeer7364]

Your Nopar sounds great😂.

[@alikazam2000]

So did you just add hollow pushrods? What rockers were those to make sure they oiled properly through the pushrod? Thanks! :) I ran a Crane Retro-fit Roller cam on a 360LA a long time ago. It was nice in that Crane used to put a Cast oil pump drive gear onto the billet shaft so you could use regular drive gear on the pump shaft. Very easy to deal with. The Edelbrock Aluminum heads I had required me to machine/slot the pushrod holes so during full travel of the cam and lifters/rockers, it wouldn't rub in the head. Glad to see this works without so much effort. The cam was a 230/238 @ 0.050, 0.528/0.548 lift, 112lsa. Maybe just more lift? Anywho. That 360 made 340whp/350wtq, NA and I had a 150hp shot if nitrous on top. :) Good luck with your rig! :)

[@Mynextproject_74]

I bought custom length hollow push rods from Comp. The stock magnum hollow push rods were about 1/2" too long. The stock Magnum lifters already push rod oil. I believe the rockers are old Comp ones but I am not sure as i bought them used. Basically any adjustable rocker should work. You are oiling it backwards from the way it was originally intended. If you notice in the video, I did plug off the original oil feed holes to the rocker shafts. This way each push rod supplies oil only to it's rocker and spring. It worked very well when spinning the pump with a drill and rolling the crank over with a ratchet.

[@alikazam2000]

@@Mynextproject_74 yeah just wanted to make sure it wasn't some one off rocker arm or something lol looks good. Curious how long this will last.

[@Mynextproject_74]

@alikazam2000 I'll update when I know. From the amount of oil getting up to the valve train, I feel it will last really well. Magnums are oiled this way, Chevies are oiled this way. I think AMCs too. I thought about upsizing the oil passages in the rockers but it doesn't seem necessary.

[@icetech6]

nice motor... i just put together a '85 LA roller (318) myself with trickflows.. will hopefully fire it up when it warms up out. BTW... walmart has some stuff called "Purple Power" in the oil isle.. it's like $13 for 2.5 gallons and works amazingly well cleaning greasy shit... i just keep a big tub of it and throw parts in to sit for a day or 2 :)

[@Mynextproject_74]

I have used Purple Power in a spray bottle. Will have to try it as a soak! Thanks for the tip!

[@kevinscott9499]

My brother has an old 360 with AAR 340 heads that the old man built in the 80’s.. it eats big blocks for lunch

[@Mynextproject_74]

They are a great engine!

[@stevea6722]

Windage tray may not make more hp but it certainly won't hurt either. Big blocks came from the factory with windage trays. Interesting build, will be watching to see how it performs. Good luck!

[@Mynextproject_74]

Thanks!

[@blakegaddis946]

I don't see why this wouldn't work. The speedmaster heads must have larger push rod holes. Normal la heads I don't think have enough room for the push rods with the magnum roller cam. I could be wrong here. I like what you're doing!

[@Mynextproject_74]

You are right about the push rod holes.Speedmaster and Edelbrock heads have a bit bigger push rod hole.

[@blakegaddis946]

@Mynextproject_74 Thanks, that's good to know!

[@tims72demon]

You’ll like that cam. Never seen anyone else use that one. I’ve got that exact cam in my 360 in my Demon. It’s right under 10:1 compression. Tops out around 5200 rpm. On the dyno mine is right about 350hp / 391 ft lbs torque. I wanted a fun street car. Maybe hit the track occasionally. Your motor is looking good. You’ll prbably do better than mine, you’ve got better heads. 👍👍👍

[@Mynextproject_74]

Thanks! I may need more compression down the road though.

[@tims72demon]

@@Mynextproject_74 mine are the stock iron heads. The old guy did a port job on them. We put a dual plane edelbrock performer on it. With a 650 edelbrock avs2 carb. Got a set of Dougs headers on it. Put an A833 tranny in. And he had a 69 b-body 8 3/4 rearend we completely gutted an put everything new in. With 3:55 sure grip. Had my interior redone. So I do want to paint it. Just not sure how far I want to go with the suspension. Been collecting tons of new parts for it. Hope I can get back to it as soon as it gets warmer. No garage, it’s very small. So the cars outside. Colorado is cold and snowy. I got old and have had health issues these past few years, so my project is dragging. But I did just get in my truck last fall and drive back to the NNN It was great to walk around and meet and talk to all the guys. And see their cars upclose. Really good bunch of people fun time. I’ll go again even if I can’t take the Demon. You going?

[@Mynextproject_74]

@tims72demon I sure hope to go. My job is such that it will always be a last minute decision for me. But I do want to drive my car from home to the event and back! Would be great to meet you and all the others.

[@drussell_]

I think you're going to suffer rapid wear and galling on the rockers and shafts without oil flowing through that interface. You could probably just plumb an external line from a tee on the oil pressure sending unit port or (oil galley plug somewhere or something) out through a tube to each head to feed the shaft oiling passageway instead of doing the long, tricky drilling job required to add the *proper* passageway down through the deck.

[@Mynextproject_74]

I'm pretty sure it will get all the oil it needs from the push rods. I can see it flowing out past the bushings and on to the head. I guess we will see. I am going to attempt to install some open top valve covers for when I put it on the run stand. Then we will see exactly what I have. I'll definitely share that too. Thanks for the comment!

[@joecurmaci5880]

In the late 60s early 70s a 340 would beat a 383

[@Mynextproject_74]

I really like my small blocks. Mostly because I like my A body Mopars and they just fit better!

[@jmflournoy386]

Are those bolts with stud tops or total studs if studs better dial indicate your mains what's your deck clearance what happened to the stock lifters, they work fine ROLL THE MOTOR OVER TILL THE CAM IS AT HALF LIFT ANDPOST A PIC FROM THE END OF THE HEAD Just eyeball it Btw adjusters need to be adjusted highest as possible you can try lash caps but rocker shafts may have to be moved up and back to get the geometry right and roller tips not running off the top of the valves (at the same time) There are kits for this and it is important do NOT run with theadjusters long, they break your pushrods may end up being too short get that line through the roller and the shaft 90 degrees to the valve stem at half lift and go from there are those trunnions rollers or bushings?

[@Mynextproject_74]

They are bolts with studs. Pistons are .050 down. I wrecked a couple lifters removing them. They are bushings where it rides on the shaft.

[@lynnrunningdeer7364]

Have you checked out David Vizard Mission Impossible?

[@Mynextproject_74]

Yes, I am following the whole thing. Those guys are at a whole other level than me!

[@joecurmaci5880]

340 is an in 360 or awesome foundations

[@jmflournoy386]

early magnum had material to drill the oil passage or run external lines, easy hope your al heads have better than LA chambers HR cam? Magnum have good metal for cylinder walls do you have hea flows radius seat on the exhaust and tulip valves (usually) back the intakes not the exhausts do you have head flows tight quench?

[@Mynextproject_74]

They are nice closed chamber heads. It is a HR cam. I don't have head flows. Quench will not be where I would like it because pistons are .050 down and it's a .039 head gasket. May swap pistons next winter and bring it up in compression and get better quench.

[@jmflournoy386]

Thanks I posted before I saw a picture of the chambers but if the pistons are .050 down it does not make much difference. Yu have to run less compression, less timing (or both) or better fuel

[@jmflournoy386]

@@Mynextproject_74 good plan it will run better I gave up on MOPARS with bad quench or no quench. The further down the hole the more throttle you have to give to get the same power which equals more heat Do spend the time to get the geometry right/ I also saw the bushings do they oil? I'd run the external lines tHE EDELBROCK BBM heads have stock chambers so I was pleased to see yours I have all the parts to do a 360 but I think I will change to more modern heads after seeing yours thanks

[@DrGo-bw2jy]

@@Mynextproject_74I might try what I saw on a David Vizard video with Andy of #unitymotorsportsgarage where they said the stock rod length of an LA 318 was 6.123 inches and they were considering using a 6.2 inch H-beam rod to bring the piston back up the bore… I know they are using open chamber heads and not sure of gasket thickness, but that discussion was considering re-using the stock piston. We all would have to do our own math with our own combinations, but I want to consider this to bring up my compression. Almost a very mini stoker. The mission 318 is supposed to go through many phases before final and may end up with new pistons too, so I am still watching for that. I wish you continued success with this build… though it is probably done and in the car by now. I am a new subscriber and have not caught up yet on your videos.

[@Mynextproject_74]

@DrGo-bw2jy I lost track of that build too. I don't think they are done with it. I found a forged 360 piston that should bring me close to zero deck height. I think that will be my next t step.

[@chapmanracing1206]

What rocker arms are those?

[@Mynextproject_74]

I think they are old Comp roller rockers, but not sure. I got them used. Almost any adjustable rocker should work.

[@sarahelgin8082]

LA rods are better. Wider pin boss.