Magnum heads on an old 360?

[Big Block Ram]

Will 360 Magnum heads bolt on to a 360 non-magnum block?

Also will a non magnum cam fit in a magnum block?

[6 packin]

Not sure about the cam but the heads will work. Changes must be done also. A switch to a AMC style lifter which then uses hollow push rods for oiling will be in order. Do a search on here for some contact on some guys that do this alot.

[goose]

If you use the Magnum heads I'm pretty sure you have to use a different intake manifold because the intake bolt pattern on the heads is different. You can also modify a non-Magnum intake to fit by drilling some new holes I believe.

I think you can use the Magnum cam if you have the lifter galley modified to use roller lifters.

[George G. Leverette]

Is this really a vbiable option considering the expense of the conversion? The Mopar performance catalogs contain the heads with swirl port technology that will out flow the Magnums and they are designed to fit the 360. This conversion has been done in the past with several articles written in the magazines and the Mopar engine book recommends it not be done then proceeds with instructions on how to do the conversion.

[darren509]

For the $ you will spend on converting to a magnum head, its less of a headache to just have the old style head reworked, or look for a J casting 340 head.

[rumblefish360]

Total expense is the heads, of course, head, intake and valve cover gaskets, tappets, hollow pushrods of proper length.
(I say this because many times people will mill the heads or block and/or change cams and head gasket thickness without thought or reguard to the little things that are not so little.)
The intake from beer barral to M-1 is no different the changing out the stock 2bbl. to a M-1.
This is a easy swap and HP gain over the old stock heads.
I don't like the expense of the intakes. But what can ya do.
Modify the LA intake? Ya, thats doable for some, not so easy for others.

[Crank]

the magnum heads are swirl port technology and yes they will out flow the the older 302 and 308 heads and they have larger valves stock with closed chambers and will increese compresion. i switch from ported 308 on my 360 to magnums that i allso ported and polished and it runs much better more torch and top end.the push rods are 60 bucks and the lifters 2.50 each and the manifold was 200.but i didn't have to mill the heads or get larger valves this is a exellent swop and i would recommend it to anyone ,personally i don't now why more people would rather have the 302 or 308's when the magnums will walk all over them stock or ported .

[Reggie]

Frank Adkins' book on HP Chrysler engines has a photo showing that the LA cam is a bit longer than the magnum cam. He said the LA cam will fit in the Magnum but an LA style timing cover may be needed to avoid clearance issues.

The magnum heads have no exhaust heat passages to warm the intake, so cold weather operation might be crappy. - RR

[George G. Leverette]

Crank this is a little confusing, I thought the 92 and newer Magnums used a different valve train configuration, oiled through the push rods and required other modifications. Will the heads bolt directly to the short block without machine work?

[Crank]

yes their is no machine work involved bolt on the heads use the AMC 360,304.401 OR 390 lifters mopar sells the push rods around 60 bucks use the stainless valves if you get bare heads the rockers are sold in sets 1.6 or 1.7 the 1.6 are stock sizes so you save money once again for around 6.50 a set you get 2-rockers 2 bolts alighnment plate and 2 rocker inserts enough for 1-cylinder .the heads do not require a lot of wotk for a ton of flow. open the bowls really helps allot gasket match the intake and exhaust ( magnum gaskets fel-pro) blend in all the ports polish the exhaust ports and combustion chambers like crome ,clean up around the seat on the combustion chamber so theirs no ridges and smooth out the spark plug hump on the chamber.deshroud around the valves ,then slap them on your 408 and go.

[451Mopar]

Quick recap,
The magnum roller lifters will not work in the older block, so you will probbably need a new cam designed for the older block.
The magnum valve train oils through hollow pushrods, so AMC style lifters are needed to provide the oil for the new valve train.
The magnum heads need the stud mounted rockers and the angle of the intake manifold bolt holes is up/down, not in-line with the heads so you need the intake manifold to fit, or modify a non-magnum intake using angled spacers between the bolts and manifold. I think the valve covers have a different bolt pattern also.

[Crank]

you got it but the old valve covers will work on the magnum heads use the older style gaskets.a Hughes cam fast ramp with 1.7 rockers = big block chevy KILLER !!!

[340duster1]

To clear up more of the issues

- the magnum camshaft is shorter, but only due to having no provisions for the fuel pump eccentric, the other dimensions are the same.

- magnum valve covers have ten bolts, LA valve covers have five. But the valve covers still bolt on! If you are using the stock stamped steel LA ones, you have to bend one of the corner lips up or grid it off. Just use the good mopar LA valve cover gaskets (metal lined/silcon coated). This is a good thing if you want to hide your magnum heads.

- For using an LA intake manifold, best/simplest solution is to redrill heads for 5/16" NC bolts. I have a jig for this and have done two sets so far, works good. Send me your heads and $50 plus shipping I'll do it for you. Or if you can weld build your own jig.

- as far as the magnum lifters not working in the old block, this might not be quite right. I haven't tried it yet but the lifter dia is the same, the only issue is there might be a little machining work to the top of the lifter bores for the lifter anti rotation retainer (for lack of a better description), and provisions for the "spider which holds the rotation retainers in place.

And to me this is a very viable swap, and very low buck. find a 92 and up truck with a 318 or 360 at the local pick a part, valve job, new springs and retainers from mopar, porting kit from mopar if you desire, pushrods from mopar (correct length for magnum heads on LA engine), oil through lifters, redrill the heads and you are off to the races. Even the accesory holes in the heads are the same spot as the LA engines.

[Crank]

DO the ports line up with the older style edlebrock manifolds?

[runinapentastar]

the 89-91 light truck block used a roller style cam the bosses in the lifter valey has been lenghten for the increased height of the liftersyou can goto a magmum cam on one of those

[340duster1]

Yeah I should have mentioned the intake ports. Port matching would be required as the magnum ports are tall and skinny. I put an edelbrock LD340 on mine.

[340king]

There has been quite a bit of good info presented here on this subject. There are a few other considerations that need to be made.

Head flow. The magnum heads that I had flow checked did not outflow the 452 (360 HS) castings that I had checked. They were actually down around 14 cfm at .500" lift. We worked hard at raising the flow within the rules and made some progress, but we never exceeded the stock flow of the 360 hs heads. Both heads used Ferrea pro-flow nail head valves with undercut stems. We trimmed the guide extensions, three angled the bowls and removed anything we could within the stock head rules.

To me the main advantage of the Magnum head is the closed or quench chamber. We ran a flat top zero deck piston to take maximum advantage of the quench area. If used correctly, I think they can make more power.

In the setup I built, we used the MP race shortblock, AMC solid lifters, an LA solid cam, cut down Chevy push rods and shaft rockers. Yes, shaft rockers. It takes a little machine work and ingenuity, but it does work. This brings me to the main downfall of the Magnum head design. Stud or bolt mounted rockers. Add to this the puny wimpy stud bosses and you can't even begin to really apply a set of race springs to these things and expect them to live. Even if they lived, the valve motion would be a joke as the spindly little studs bent all over the place. Hence the shaft rockers.

The engine is back in my shop after two years of campaigning on the circle track. It pulls hard! Now a 340 Magnum engine is in the works to supplement the 360 Magnum engine.

[340duster1]

340king

You used cut down chev pushrods. Can you explain what you did to do this. I currently use a magnum engine in my circle track car and once at about 6000 rpm the stock pushrods tend to jump out of the rockers. I believe that the stock pushrods are flexing. So right now I set my rev limiter to 5800 and have had no valve train issues.

[340king]

We took a set of long Chevy pushrods and removed the pressed in ends. (You could also take a cut to fit kit and do the same thing.) Then cut the pushrods to length. They are a 5/16" chrome moly pushrod and seem to be quite happy with real race springs and up to 7,000 rpm.

I would be concerned that your valve springs aren't up to the rpm abuse if you are losing the rocker contact with the pushrod, rather than pushrod flexing. There must be about 1/8" of cup to cap interference fit. So you would have to flex the pushrod enough to be 1/8"+ shorter. This would have to occur when the valve is at the seat since at any lift, the spring has to force the rocker onto the pushrod. Theoreticaly, there is virtually no flex in the pushrod when the valve is on the seat. So I don't think that is what is happening. I am 99% sure you are having a spring problem.

[340duster1]

The push rods are usually bent when they are removed, so I assumed it was the push rods. But it is the old chicken and the egg thing, which happened first. The springs I am using are the mopar perf. ones I don't have the part number handy but it is the less expensive of the two types mopar sells for the magnum heads. Anymore ideas? Are these springs good?

[myduster360]

i agree with most of whats been said. magnum swap isn't that hard. especially with mp pushrods. it took me quite a while 4 years ago when i swapped to figure out the right length.

my main reason for the swap was for a cheap mpi 4bl manifold. MP's p5249816 uses stock tb AND fuel rail, making my Duster's mpi conversion SUPER simple useing readily availibly FACTORY truck parts. no EXPENSIVE manifold/fuel rail conversion and fabrication or MEGA BUCK throttle body needed.

if id do it again i fing a WHOLE magnum engine. no swapin parts all the ROLLER cam stuff is there(88 and older blocks lifter bores are TOO SHORT for factory roller lifters, besides having NO lifter retainer bosses) for one thing. AND THE BIGGEST PLUS OF A MAGNUM's SHORT BLOCK!!!!!! 1.5mm/1.5mm/3mm piston rings!! Racers pay BIG bucks for pistons that use 1/16 rings for a big power boost from lower friction. the magnum's rings ARE JUST AS THIN!! Worried about oil consumption for the long term? Im not. ive seen PLENTY of 100K++ trucks barely use ANY oil!
right now im hunting for a 360 magnum COMPLETE. thats what i suggest anyone else do if they want magnum heads.
1: Junkyard 360 magnum
2: Magnum M1,singal or dual plane, HINT: if you get the mpi manifold, you can plug the holes with old injectors like i did for a while and use a carb, till you can bank roll the rest(ECU,pump, lines,ect,,)
3: Crate motor ROLLER cam or any other roller Mp has or get one form Hughes