Magnum heads on LA block H.p increase
- Thread starter Slantsix64
- Start date
-
MOPAROFFICIAL
Oogliboogli
I wish they were 175cc.
Cracks grow up into the bowl where there is water, beyond the seat there is plenty of water in a mopar head. Trust me.lol
The 2.02 versions go over 210 cfm and some as a high as 228cfm
The tulip 2.02 actually eats up more bowl volume than the 1.88 and is about the same bowl size aside for the minor throat plunge front the factory.
Back to the topic..
The mag'em heads will outperform the 302 318 heads no problem and wont lower the compression or gain any either 'as cast'.
It's a worthwhile upgrade if you can $wing all the gear to make it work. In this case just some push rods, the heads & rockers... if or just buy sheistmasters chi'luminum for a few bones if I were trying to save money and don't mind modifying the alt brackets some. Same everything n bolts right up.
A good set of mag based performance heads 'ready to rock' will set you back into the 950-1200 range depending on how you dress them.
Hmm okay so larger valve stock X and J heads flow about the same as stock magnum heads. Only with larger valves. I have a set of J heads that look like your magnum heads exhaust seats gone and intakes on the way out.
How many miles do your magnum heads have? I think indy still repairs the magnum heads 2-300 per head.
Volumetric efficiency has alot to do with getting as much air through a small port as possible. So 200cfm through a small port will make more usable hp than a head that does 200cfm through a large port.
Guess maybe it depends on what kind of hp you want to make over 400 and different or ported heads. Point of diminishing returns on valve size on a 3.91 bore is around 1.97" 4.02 bore is around 2.05 if I remember correctly. After those sizes the valve starts getting shrouded.
How many miles do your magnum heads have? I think indy still repairs the magnum heads 2-300 per head.
Volumetric efficiency has alot to do with getting as much air through a small port as possible. So 200cfm through a small port will make more usable hp than a head that does 200cfm through a large port.
Guess maybe it depends on what kind of hp you want to make over 400 and different or ported heads. Point of diminishing returns on valve size on a 3.91 bore is around 1.97" 4.02 bore is around 2.05 if I remember correctly. After those sizes the valve starts getting shrouded.
Hey! speaking of cracks and leaking... can you empty your inbox? .. it's really full
MOPAROFFICIAL
Oogliboogli
You try hard.
Rpm range and cid help determine port volume requirements.
I get it, you like magnum heads. Mo power to ya.
I like whatever happens to fit the bill or can be made to. . But Stock Mag'ems have a limited window for my builds.
To mag'em or not to mag'em...that's the op's question. I say he should go for it if he gets a deal on some...cause they'll make more power than his 302 heads as is.
K.O. SWINGER
Meeting in the alley since 1976
So Magnum heads are good little heads and the small Chambers are a definite plus for a 318 but only really makes sense if you get a good pair of cheap. 400 horses maybe if you really have the rest of your motor dialed in I don't see it with the 600 CFM carburetor. It would take a pretty serious supporting cast even to gain 35 horses over 302s. But it would be an upgrade.
Sorry I'm not trying to offend anyone. I like all mopars.
I'm just trying to figure out where people are getting thier numbers for calculating volumetric efficiency? And longevity? I'm not saying magnum heads are all that but out of the box stock with smaller valve they flow with the X and J heads with larger valves out of the box stock. So yeah depends on complete build like pistons compression, deck height ect... correct?
I'm just trying to figure out where people are getting thier numbers for calculating volumetric efficiency? And longevity? I'm not saying magnum heads are all that but out of the box stock with smaller valve they flow with the X and J heads with larger valves out of the box stock. So yeah depends on complete build like pistons compression, deck height ect... correct?
MOPAROFFICIAL
Oogliboogli
They flow close, close enough its splitting hairs. They have a bigger valve than the heads they flow more than=1.88 They are not an underdog head pulling ahead of the pack.
They were a smog head. I have a flow bench and flowed all these heads to say what i say.
Last edited:
MOPAROFFICIAL
Oogliboogli
This thread is **** now.
Slantsix64
Well-Known Member
What i like about this swap is my lift on my roller camshaft will increase from .410/.423 to around .430/453 with the 1.6 rockers Via camcard. The heads on there now are 64cc (302) The magnum heads i just CC'd came out to 62cc, Plus those bigger valves. Gotta love it!! Cant wait to take it back to the track when im done
Slantsix64
Well-Known Member
Also iam a little confused reading on the swap from La heads to magnum everyone is saying to use AMC style lifters because the magnum heads oil up through the push rods, since i have a LA Roller 318 block with roller lifters already i can just reuse my current lifters? or should i use the magnum roller lifters from the magnum block?
And i been reading that some had issues with the push rod hole in the magnum heads they had to open them up a bit.
And i been reading that some had issues with the push rod hole in the magnum heads they had to open them up a bit.
I don't anyone here is trying to offend you. We're hungry for information. I have a set of "J" heads, a set of "Z" heads, and the Magnum heads from a 1998 Jeep Cherokee. I'm making a 408 for another project with the block, and don't need the cranks or heads. 113K total miles. I guess I'll move this to the for sale thread, so as not to invite the ire of the MODS.
DionR
Well-Known Member
Pretty sure the lifters you have and ones from a Magnum are the same. Just make sure they have a hole in the cup and you should be good to go.
Pretty sure that is only when the Magnum heads are used with a flat tappet cam. The FT lifters are shorter and change the angle of the pushrod which can make them rub. If you use the roller lifters, you shouldn't have an issue.
Reading through this post hearing the pros and cons of the magnum heads and just wondering how fast some of you guys have gone with them. I’m honestly impressed with what I’ve seen out of a set on a friends engine. What do you guys think a 408 magnum engine with a hydraulic roller, flat top pistons, ported magnum heads with 2.05 intake valves, 750 alcohol carb, powerglide, at 3200 pounds. What do you think this combo would run in the 1/8 mile.
If memory serves me correctly the pre-magnum roller lifters have the oiling hole but better double check. And I would personally run a roller cam short snout for a magnum is ok if you run a electric fuel pump or get the adapter for mechanical fuel pump.
I don't remember the 1/8 mile times on the 5.9 magnum. Locomotion a member here I believe was running into the upper 12's in the 1/4 with the 300hp 5.9 crate engine. And the 300hp crate engine was a factory stock 5.9 truck engine with a long snout cam for fuel pump but same specs as production truck engine.
The 380hp was a completely stock 5.9 they pulled off of the assembly line and changed the cam and valve springs. And ran a light weight A-body into the mid to high 11's in the 1/4
Those 2 engines were dyno tested at those hp levels by the factory with 600 or 650cfm carbs. Add a 750cfm carb and the 380 jumped over 400hp and the 300 I belive went to 320. Somewhere in that ballpark anyway
I don't remember the 1/8 mile times on the 5.9 magnum. Locomotion a member here I believe was running into the upper 12's in the 1/4 with the 300hp 5.9 crate engine. And the 300hp crate engine was a factory stock 5.9 truck engine with a long snout cam for fuel pump but same specs as production truck engine.
The 380hp was a completely stock 5.9 they pulled off of the assembly line and changed the cam and valve springs. And ran a light weight A-body into the mid to high 11's in the 1/4
Those 2 engines were dyno tested at those hp levels by the factory with 600 or 650cfm carbs. Add a 750cfm carb and the 380 jumped over 400hp and the 300 I belive went to 320. Somewhere in that ballpark anyway
The mopar performance magnum stroker I believe was 435hp and rather same cam as the 380hp. With a well tuned chasis and engine I would think low 11's in the quarter would be realistic.
I ran a Mopar Performance hydraulic roller in a stock 5.2 engine in a 3650 pound Dakota long box regular cab . 8.80's in the 1/8 with severe traction problems. Had a mopar computer and hooker super comp's.
Here is a somewhat thread on the cam specs for the 300hp and 380hp and a few other mopar performance cams. The one I was running is in the thread. Just posting to give a ball park idea of what the factory did
I ran a Mopar Performance hydraulic roller in a stock 5.2 engine in a 3650 pound Dakota long box regular cab . 8.80's in the 1/8 with severe traction problems. Had a mopar computer and hooker super comp's.
Here is a somewhat thread on the cam specs for the 300hp and 380hp and a few other mopar performance cams. The one I was running is in the thread. Just posting to give a ball park idea of what the factory did
to fill in the blank on this this engine has gone 6.70’s (10.50) but he loses almost .20 as he foot brakes the car a lot and when he does he “deep stages” the car. So I can’t remember if this was deep staged or not. I do know his Dad has had a set of TrickFlow heads and is hesitant about putting them on till we do some flow testing on my flowbench. He’s kicking around at least putting a 2.05 valve in them before running them. Like I said before if I had a mule engine, still enjoyed working on cars, I would probably port a set (magnum heads) as they can be a damn good head.
Yeah that would be a toss up. The magnum setup would have a little better port velocity and compression. The Trick Flow would flow a more at the cost of velocity and the chambers are a little larger arnt they? So may loose a little compression. But they might loosen up some hp.
That is kinda a tough one
That is kinda a tough one
I read page 1 of this thread and about half of page 2 but I have done the EQ magnum head swap on a 318 LA in an 83 D250. Used a stock 360-2bnl cam very much a dead ringer for a COMP 252.
Untouched stock 130k 83 short block. Added a performer (not RPM) intake and 625 carb. BIG feelable difference in seat of the pants, towing or empty. Better mileage too. Would be even more noticeable in a light A body....
Untouched stock 130k 83 short block. Added a performer (not RPM) intake and 625 carb. BIG feelable difference in seat of the pants, towing or empty. Better mileage too. Would be even more noticeable in a light A body....
-
