Chrysler Magnum head flowed stock vs. 360 LA J head flowed stock.

For Mopar fans: We discuss the changes in technology and flow numbers, air speed discussion and swirl. The difference in port sizes and shapes.

[@elliottmagnum4998]

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.

[@servediocylinderheads]

Thanks

[@obbyjep7597]

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

[@servediocylinderheads]

I agree. Thanks

[@darrylsmith7908]

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?

[@servediocylinderheads]

I have not done any Mopar heads for customers in many years. For what I would charge move up to a much better aluminum head. Thanks

[@paintnamer6403]

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

[@servediocylinderheads]

Not this time. Sorry

[@TheProchargedmopar]

Very interesting perspectives. 👍💪

[@servediocylinderheads]

Thanks

[@MP-pz9oe]

Thank you for your honesty ; in other words is not cost effective to pay a professional porter to work old cast iron heads. Like you said is better to invest in aluminum heads, you get what you paid for.

[@servediocylinderheads]

It is only cost effective if you need max performance and you are mandated or restricted to a cast head. Sleeper stuff for sneaky guys too. I love sleeper projects which is what the Mission Impossible project is in a way. Thanks

[@v8packard]

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.

[@servediocylinderheads]

AMC actually used airflow testing in their designs.

[@dh2360]

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.

[@servediocylinderheads]

Sorry, not this time. Thanks

[@grahamm3559]

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.

[@servediocylinderheads]

I could be hired for that. I am expensive, and slow!

[@raysimon1368]

I have got 265 cfm on a super flow bench with stock valves with a factory magnum head at 550 lift beat a new eldelbrock rpm head from 100 to 550 lift you can do just a bowl port and good valve job and get 250 cfm real easy best small block factory head I ever ported hi velocity runners too with a good chamber with light weight valves that are 5/16s not 8mm but splitting hairs but that's what they measure take the same engine run the ported magnums at the track against the ported X or J heads and you will see a time difference

[@stuartwall8212]

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.

[@servediocylinderheads]

Yes, I agree. Too bad they crack!

[@brianlevan339]

Nice video, thanks !

[@servediocylinderheads]

Thank you too!

[@vipottaja]

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.

[@servediocylinderheads]

All good observations. Thanks

[@brokentoolgarage]

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

[@servediocylinderheads]

Good info. Thanks

[@user-nv2co2pe3y]

Oem heads what I understand we're weak from the factory the Magnum oem head had a alot of problems cracking. There are alot of people doing repairs on them. There still an oem. I went with Indy cast iron. They are supposed to be a better head.

[@Patrick-xd8jv]

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

[@servediocylinderheads]

I hate to port crack prone heads. Just too much time for something that has a good chance of failing. I won't port Chevy Vortec for the same reason. Thanks

[@v8packard]

​@@servediocylinderheads The EQ heads and others like are not crack prone. The current Chinese version cleans up and is about equivalent to the OEM heads. The older New Zealand made castings were much better.

[@servediocylinderheads]

@@v8packard I liked the New Zeland Chevy vortec. Nice cylinder head

[@v8packard]

@@servediocylinderheads So did I! It was the only OEM style Chevy head I was willing to put money into for a number of years.

[@servediocylinderheads]

@@v8packard I can see that. I did a quicky cleanup on one cut for 2.02/1.6 combo at D.V.'s shop. 275/200 cfm no development work. Tough to beat.

[@andrewburlock2653]

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 )

[@servediocylinderheads]

Similar flow with a smaller port improves velocity and cylinder filling. This equals improved torque. Thanks

[@rayowens4355]

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?

[@servediocylinderheads]

Study the airspeed for that head. It is very interesting. Thanks

[@bcbloc02]

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.

[@servediocylinderheads]

I thought they were 360 design just extra cylinders.

[@bcbloc02]

@@servediocylinderheads nope they have symmetrical individual ports and look kind of gen 1 ls style

[@servediocylinderheads]

@@bcbloc02 Are they 360 style ports just arranged differently?

[@Robs-Garage-experiments]

Charlie, IIRC, the Magnum Head is 58cc’s. The J heads are 72cc, + or - 2cc.

[@servediocylinderheads]

Excellent Rob, do you have the port cc's for us? I am very lazy. Thanks

[@Robs-Garage-experiments]

Off hand, I don’t remember. I had read it somewhere and IIRC, it’s 10cc down from the J head. If I had to apply a number, I could be wrong in saying 160cc for the intake runner. I just can not clearly remember to say with confidence.

[@servediocylinderheads]

@@Robs-Garage-experiments I think I need to do all the numbers to do a D.V. iop program sim on these two heads. I know the outcome already but will be good to see.

[@dang5553]

The CC hell no not stock there more like 64-65cc heads for iron magnums LA 68-72 Cc

[@Robs-Garage-experiments]

Hey Dang5553, those are book listed numbers and used for racing purposes. As for myself, I have had 4 J heads sets that have all cc’d @ 72 cc. I have measured one at 76 cc. I have seen smaller cc chambers on these heads but they have always been milled.

[@Manofconstantsorrowsu]

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

[@servediocylinderheads]

I have no idea.

[@JT-ko3rv]

Nope all the same exhaust pattern, different intake, rockers and rocker oiling

[@HoosierRooster]

It's a shame that they're 18 degree heads and they are that week

[@WrecklessEnterainment]

How would a magnum compare to a 2.02 J head?

[@servediocylinderheads]

If you look around I may have done that exact test video.

[@randallrussell3842]

The magnum heads were the same between 318 and 360 cu. Variants so that may explain the compromise on the intake side.?

[@servediocylinderheads]

I don't know.

[@user-nv2co2pe3y]

How does this compare with the Indy and EQ heads they are supposed to e high flow heads have you ever flow tested either one of those heads. They were supposed to have been redesigned. Tha k you for your time and making the video. Good job!

[@servediocylinderheads]

Never worked with the Indy design.

[@servediocylinderheads]

Thanks

[@user-nv2co2pe3y]

Engine Quest out of Nevada use to make a decent after market head in later years I heard that they cheapen up the heads it use to be they're heads came from a foundry they had in New Zealand I think. I don't know about aluminum heads I try to stay away from them. Anyway that's what I know. Hughes engine did my machine work on my heads. He said new heads or not they all need to be machined even if they are brand new out of the box.

[@user-nv2co2pe3y]

@@servediocylinderheads if you find a good source for a good quality after market head let me know indy doesn't make that cast iron head any more.

[@servediocylinderheads]

@@user-nv2co2pe3y Find some New Zeland eq's they are nice. Thanks

[@ThePaulv12]

Nice crack at 4:20

[@servediocylinderheads]

Cracked right from the factory!

[@JT-ko3rv]

Both heads perform about the same on the track negligible difference on equal engines. Magnums generally bit better torque street guys like them. The pinch has nothing to do with design or flow and everything to do with necessity. Roller cams on later engines requires more clearance due to the taller lifters and more severe pushrod angle. The bulge got huge because of roller cams started with the 302 casting 318 and 308 casting 360 LA heads. The blocks are mostly unchanged from the poly (canted) valve engine days 48 degrees is the proper lifter angle as can be had on the race blocks not really a requirement unless your turning over 7500rpm sustained. Won't make much more than 600hp without an offset rocker head that eliminates the pinch. Oe unported 450HP is about the limit. Chrysler new it and every performance head from chrysler had offset rockers for a reason. 3 years after production the TA heads 915 casting too finish machine work (pushrod holes) were machined for offset rockers so the race teams could port the pinch out.

[@servediocylinderheads]

Good info, thanks

[@michaelcasper2233]

Quite the teacher

[@servediocylinderheads]

Hmmm, is this Big Mike from L.I.?

[@robertwest3093]

Is it true that the factory left the sharp edge on the intake valve instead of a back cut so as to break up fuel? Or were they just doing as little as necessary to get by? At least Mopar put some thought into their design. Keeping the guide boss small and using smaller stem valves are two reasons why the 1.88 valve flows respectably.

[@servediocylinderheads]

1.92" on the Magnum. A little thought.

[@dang5553]

Yes the truth is out bout magnum heads. A lot of people thought they flowed around 200 on the intake. They got confused with the RHS heads please come back RHS SM mopar heads. Big thing that was found a single pattern camshafts can be used with magnum heads. To the LA heads those damn heads look a lot like 596 iron head from 77-80 I think. I did see the casting numbers but wow. My big question for your j heads. I know your guides are messed up but could you fit a 15/16 socket in where the exhaust valve goes. I’ve see on multiple 574 308 heads after bowel clean up it’s possible

[@servediocylinderheads]

Sorry, I don't measure by socket. Socket manufacturers have different wall thickness.

[@servediocylinderheads]

915 casting

[@servediocylinderheads]

Thanks

[@michaelstrafello7346]

I thought the magnum heads were supposed to flow better than the 915 heads. isn't one or both ports raised?

[@servediocylinderheads]

Looks like the exhaust port floor was raised. Much better design on Magnum.

[@daviddematos7470]

What Cam U suggestions for street n race for magnum only

[@servediocylinderheads]

One that will do the rpm you want to run. Match the compression, head flow, car weight, torque converter and gears.

[@Link-we8so]

What would be your first moves to improve them?

[@servediocylinderheads]

Good valve job.

[@oops1952]

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

[@servediocylinderheads]

I bet alot better. Bigger valve makes a huge difference if done right.

[@oops1952]

@@servediocylinderheads Thanks for the response....Back in the day, I was told the stock dodge 2.02 was better than the chevy but the chev did better with their exhaust. The claim was headers helped the chev more because of the good exhaust flow....thanks again

[@arturozarate1752]

All good Charles. Makes me curious now. Was there that much improvement in the Ford line? Specifically the GT40 vs. GT40p......eh, eh, yeah?

[@servediocylinderheads]

There is quite a change from E7 to Gt40 to gt40p.

[@arturozarate1752]

@@servediocylinderheads I'm looking at your older videos now.

[@arturozarate1752]

@@servediocylinderheads I had first hand experience with GT40's off my 93 Cobra back in 2000. In 2002, almost one year out of school, I was bestowed the honor of porting on the GT40P and fitting them on an SN95 Saleen running a, now extinct, TTI single 60-1 turbo kit. Not familiar with the GT40P, I squared up the intake and exhaust inlets and outlets with a 3/8" radius and removing the smallest amount of metal. Gasket fitment was nice on both sides so I moved to the chamber and valve job. I manually cut 5 angles on the valve seats with a neway manual carbide cutter set. Then I just blended everthing 1st to a 40 grit cartridge roll, then 60 grit where I left the intake runner. I polished out the exhaust and chambers all the way to a red cross buff and using a lot of WD-40 as a lubricant. The only material, other than from the cartridge rolls,removed from the heads was at the valve guide. They looked amazing. I started thinking about comparing the 2 heads, but 21 years later I'm still trying to see the comparison. It looks like I'm going to see the major differences here. Thanks Charles.

[@servediocylinderheads]

@@arturozarate1752 Fun to look back at old projects. I bet it ran real well. Thanks

[@arturozarate1752]

@@servediocylinderheads it did and still does. I never got back into them although I wanted to. I spent 3 months touching EVERYTHING on my GT40s for my Cobra, and after doing some math I remember that the "P's" were better on paper. So I bought some AFR 205's and built the "Lil Meheeco" 311 long rod 12:1 Mexican block and it sounded killer with a solid roller at 6,800rpm.

[@dwaynehagle7445]

An the tail on the LA guide is Going the wrong Direction.

[@servediocylinderheads]

Maybe, but my swirl is good.

[@oikkuoek]

Holy crap, those are bad. Although, when they are designed to run between 1500 and 4500, it probably doesn't matter. Some kind of hole somewhere and let the CI's do the rest. Throw harder leaf springs at the back, so it does burnouts, and no one will notice.. But man, so bad. That Ford head had a lot better thing going.

[@servediocylinderheads]

That argument could be made. Thanks

[@wakeUPdummies]

There isn't an early magnum head that isn't cracked, and still on the street.

[@servediocylinderheads]

I believe it