Thank you for this, there has been arguments over the magnum vs the j heads for years it's neat what you are doing , I very much injoy it.

I’m really glad someone is actually documenting these mopar heads. How much does it usually cost to get a set of mopar sb heads fully ported?

Very interesting perspectives. 👍💪

Very interesting. I can't wait for the porting, if you have time for that.

Thanks for showing this, good info especial y for guys trying to get a little more power on a budget. Find a set not cracked and clean them up, could be ahead in power

Nice video, thanks !

Thank you for your honesty ; in other words is not cost effective to pay a professional porter to work old cast iron heads.

The Magnum head is basically the AMC v8 design put onto the Mopar LA. AMC was preparing a refresh of their v8 in the late 1980s, and had completed or nearly completed this work when acquired by Chrysler. Chrysler needed to update the small blocks, and simply used what AMC had completed. This is why the Magnum head uses the AMC valvetrain.

It would be great if you did a light port job maintaining stock valves on the Magnum head and LA J head and then compared their CFM and swirl rates.

Nicely done video. Would love to see what you could get out of the magnums with porting. Apparently the aftermarket replacement castings aren't so crack prone.

Nice! Hughes engines has flow numbers for the 360 and magnum heads too, if you want to compare. Looks like you found one of the major drawbacks to the factory magnum head - they are cracked

Thanks so much for this video! There is very little good info on porting these heads. 90% of the videos they grind out the pinch point and not much else. One of the things I have wondered is why the roof of the port at the pinch point is narrower than the floor. Does it maybe have to do with the intake having tight bend at the exit causing the velocity to be higher on the floor at the entrance of the port?

Hi Charlie. Wow I have not seen a pinch area that small. I should say narrow because it is tallish. At first glance it looks like it would not work but it does. It might not be a great performance head but probably good for what it was designed for. It is also interesting that they made the exhaust so much better but the intakes have similar flow. It makes you wonder, the engineers could design a head any way they want so why do they do what they do? Andrew P.S. It is supposed to snow about 4 or 5 inches here on Sunday. ( sad face )

Really good info 👍....How would the intake on the old 2.02 340 head stack up to the magnum?

Moving up to magnum heads from a la are the exhaust ports different for headers?Thanks for your time I learned a lot.

flow maxed at .4, maybe somewhere between .35 and .4 the air detached from SSR as swirl had big increase at .4 and above. Wide SSR to help keep it attached? slowed airspeed elsewhere.....I think a lot of thought went into the design of this head to perform this well stock at the given cam lift. Too bad it is crack prone.

Somehting that me as a complete amateur have noticed. The magnum intake bowl is very deep, and the long side shape isn't very smooth, more like angular where it makes the turn to the bowl. And in addition to the very small pushrod pinch, also the rocker arm stud boss is huge. The exhaust is really nice, but it still has the waterhump in the roof.

Quite the teacher

Now I am super curious if you could cut one cylinder off the v-10 heads and use those. I think the ports and manifolds are about a million times better than any of this stuff. I don't know if the head bolt holes will line up or not. Research some day.

Porter Magnum heads would be really interesting on the 318. Quality and quantity flow