Magnum heads on a 340

[Darryl]

I’ve got a 340/373 stroker and I’ve got two sets of heads. I’ve got ported 318 heads with a 1.88 intake 1.6 exhaust and a set of stock magnum heads. I know the magnums will make more power but how would I retrofit them into the LA 340?

 

[MoparLeo]

There are many articles and videos on this. Basically you will need to use AMC lifters that have oil holes in them that allow oil to pump up through the pushrods which need to be hollow.
The intake manifold needs to be for a Magnum as well. The intake mounting holes are vertical on the Magnum. Use can use the same valve covers as the Magnum have more mounting holes to help with gasket leaks but the standard cover will still fit, just does not use all the mounting holes.
Read this link on Magnum swaps. It will tell you what is and is not interchangeable. Enjoy.
http://www.magnumswap.com/using-la-parts-on-a-magnum/

 

[BeatersRus]

you are going in the right direction,magnum heads have nice flow numbers But,
also fair warning,99% of magnum heads are cracked,between the seats.
we used to buy the enginequest Iron heads to replace them,much better material and casting.
you can run the stock heads cracked,it doesnt seem to hurt at all,as theres literally thousands running out there right now still.
just wanted you to be aware.

also be aware that if you plan to Retain ac,the cheaper magnum 4bbl intakes dont have bosses for the bracket braces off the ac unit itself.

 

[Darryl]

you are going in the right direction,magnum heads have nice flow numbers But,
also fair warning,99% of magnum heads are cracked,between the seats.
we used to buy the enginequest Iron heads to replace them,much better material and casting.
you can run the stock heads cracked,it doesnt seem to hurt at all,as theres literally thousands running out there right now still.
just wanted you to be aware.

also be aware that if you plan to Retain ac,the cheaper magnum 4bbl intakes dont have bosses for the bracket braces off the ac unit itself.

Speaking of the A/C brackets, the ones off the original RV-2 don’t actually work with my RPM air gap intake I have which I will run on either set of heads, do I actually need the brackets behind the RV-2 or are they necessary. I am going to re-drill slanted intake holes in the magnum heads so I can run the Air gap.

 

[rumblefish360]

AMC lifters. They can oil the new hollow, oil through pushrods you’ll need to get at a new length.

Choose the head that flows the most air through out the lift range. If you need to flow test both heads, do so, it’s worth the cost.

The front of your engine can be a trick though. I suggest using the OE serpentine system for ease.

 

[Darryl]

AMC lifters. They can oil the new hollow, oil through pushrods you’ll need to get at a new length.

Choose the head that flows the most air through out the lift range. If you need to flow test both heads, do so, it’s worth the cost.

The front of your engine can be a trick though. I suggest using the OE serpentine system for ease.

AMC lifters for a what though an AMC 360?

 

[MoparLeo]

Dump the old rv-2 compressor and get a smaller, more efficient Sanden type. They also sell adapter mounting brackets since they didn't come OE on any of the old cars but many people use them.
https://www.originalair.com/mopar-compressor-upgrades

 

[rumblefish360]

AMC lifters for a what though an AMC 360?

LMAO-OMGosh… yea man, any Hyd cam AMV V-8. There dimensionally the same as a MoParz

 

[Slap Stick]

The valvetrain on the Magnum engines was designed by former AMC engineers. As I understand the team responsible was half Chrysler, half former AMC.

 

[dvw]

I've used the stock timing cover and pulleys. You will need 45 degree adapter for the bypass hose. You can bend the throttle bracket tabs to fit the Magnum intake bolt angle.
Doug

 

[Bighead440]

Did this to a '70 Challenger 340 convertible that had previously been rebuilt with TRW '72-3 low compression forged replacement pistons. The original 2.02 LA heads were still on the original block, but the customer wanted more power. I used stock Magnum castings with .525" MoPar springs/retainers, and a China air-gap intake, kept his small tube headers and ran a Lunati VooDoo 262 cam (came with oiling lifters) and MoPar Perf pushrods for the flat tappet swap. My customer swears it has 100hp (LOL) more than the original setup (had a LD340 intake and a 280H Comp cam in it), with much better driveability. Also did this to a fresh .030" over dished piston 360 with a 256 VooDoo for a '74 Dart Sport with adjustable rockers (1.6/1.5 Scorpion SBC) and custom length pushrods (Trick Flow).

 

[rumblefish360]

That’s a much better cam and head combo to move that ride. Makes me wonder where the intake valve opening points are on the cam vs cam.