360 Magnum Heads

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wes beem

wes beem

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Mild 360 magnum build, toying with getting the Edelbrock performer aluminum heads but that is a massive chunk of change to drop.

Done alot of research but what i've never been able to find was an apples to apples comparison video where a motor Dynod (X) Horsepower with the stock heads and then Dynod (X) horsepower by swapping to the eddys with NO other modifications so that I have a base line of just what that 2000$ check is getting me flow/HP wise and whether or not id be better off just having a shop port and polish my stock heads for less money. Has anyone here done such a test and confirm or deny that you will actually make noticeably better power with the Eddys over stocks?

Ill be running dougs long tube headers, dual exhaust, probably magnaflow or borlas or something of the like, Eddy air gap carb intake, prolly a holley 650-750 MSD iginition, and a mild cam. Horsepower goal is somewhere around 400-450, but if thats not achieveable without tearing into the bottom end and messing with pistons im ok with less.
 
I saw a comparo on U-tube where they dyno'ed a factory rebuilt 440 with iron heads. Then within hours dyno'ed it again but with alloy heads. The difference was very small. What she mighta gained in power, she lost to the lack of increased cylinder pressure.
Some books say that alloy heads suck so much heat out of the chambers that you need an extra half a point of Scr just to break even. I think it's actually more.
To get the most out of alloy heads, you need to increase the compression ratio. But not just the Scr, more importantly, the cylinder pressure. So if you are not gonna fix the pressure issue, and with only a mild cam, Ima thinking alloy heads are sort of a waste of money, on such a combo.

Now let me tell you about that.
If you build it right, you can get the cost of the pistons and boring back in fuel costs in just a few years, and enjoy the torque and power for the whole time.
I built and am extremely pleased with my alloy-headed hi-compression (11:1) 360, and it burns 87E10 100% of the time, with full ignition timing. It has run three different cams, with pressures set between 180 to as high as 195 psi, with no detonation. The build wasn't cheap but it has gone over 100,000 miles now, since 1999.
I would sacrifice the Airgap, the Holley, and the MSD, to get some hi-compression pistons into her. With a mild cam, you won't need any of those; just throw any old junk up top, and the MSD is overkill as well.
My 360, with KB107s came together with a deck height of .012 clearance which is 2.5cc. The pistons are flat-tops with 5cc eyebrows. The Eddies were 63cc. the .028 gasket is 6.8cc for a total of 77.3cc
If your engine cleans up at .020 your swept will be 744.6cc. Therefore your Scr would be;
(744.3 + 77.3)/77.3= 10.6 to 1
Put a mild cam into that with an Ica of say 58*, and she will generate about 180psi, or more depending on your local elevation.. I guarantee you, that on the street, you will not care about how much power it might be making, because it will be so much fun to drive.
You could even run it with a 2bbl up top, for most of the time...... I kid you not.
If for some reason you have to deck the block, I would pop the pistons up out of the holes and run the FelPro .039s at a Quench distance of .030/.032.
This engine has the potential to put your A-body into the 12s on street-suspension.
The small cam will make monster torque, and if you tune it right, has the potential to make great fuel economy. And it will like an overdrive so you can gear the back to optimize Second gear.
Those heads, together with the right small cam(and springs), will have a looooooong flat power curve, that will allow her to rev deep into the 6000s (I shifted mine at 7200, just cuz). So then you gotta do some oiling system mods to not lose a rod, cuz Ima thinking after the first time you try it, you are gonna be addicted.

But, if you are building this for street-duty, and
are dead-set against opening up the bottom, and
are sure about the small cam; then
IMO,
I would leave the expensive alloy heads on the shelf.
By themselves with no supporting changes, they might be worth one cam size, at full-power. But they might actually lose power at low to mid rpms, because of their ability to take heat out of the chambers.
 
Interesting read, i was under the impression higher compression = less economy.
 
My main reason for not messing with the bottom end is there are no shops anywhere near me i trust to do any of the bottom end work on it without douching it up.
 
wes beem said:
Interesting read, i was under the impression higher compression = less economy.
Click to expand...
Just the reverse. Aluminum heads do not need more compression. That’s a myth busted proven over and over again.
 
wes beem said:
My main reason for not messing with the bottom end is there are no shops anywhere near me i trust to do any of the bottom end work on it without douching it up.
Click to expand...

If there’s no one you’d trust with the basic machine work, who would you trust to port and/or do a valve job on your stock heads?

To make 400-450hp from a 360 magnum, you’ll need a cam that will require a valve spring change from stock.

The old MP crate motors hit 380+ hp. 9:1 compression with M1 single plane intake, and 750 Holley carb. Lots of duration, not much lift so they could use stock rockers.
 
Here's an idea for ya... Instead of buying $2,000 heads which we all know will cost more than that once you get all the correct pieces to install them, $1,000 plus Doug's headers which basically don't do much and in the ballpark of 800 to $1,000 for MSD ignition which ain't going to do nothing but empty your wallet over a stock ignition.... Add up that $4,000 and what you have for an engine now and sell it and buy a blueprint engine that comes with a Dyno sheet for the horsepower you're looking for...
Drop it in with some cheap headers and stock ignition and light your world on fire....
My-2....
 
wes beem said:
Mild 360 magnum build, toying with getting the Edelbrock performer aluminum heads but that is a massive chunk of change to drop.

Done alot of research but what i've never been able to find was an apples to apples comparison video where a motor Dynod (X) Horsepower with the stock heads and then Dynod (X) horsepower by swapping to the eddys with NO other modifications so that I have a base line of just what that 2000$ check is getting me flow/HP wise and whether or not id be better off just having a shop port and polish my stock heads for less money. Has anyone here done such a test and confirm or deny that you will actually make noticeably better power with the Eddys over stocks?

Ill be running dougs long tube headers, dual exhaust, probably magnaflow or borlas or something of the like, Eddy air gap carb intake, prolly a holley 650-750 MSD iginition, and a mild cam. Horsepower goal is somewhere around 400-450, but if thats not achieveable without tearing into the bottom end and messing with pistons im ok with less.
Click to expand...
Your goals can be reached using the stock magnum heads. If they are not cracked, best bang for the buck may be just running them.
 
j par said:
Here's an idea for ya... Instead of buying $2,000 heads which we all know will cost more than that once you get all the correct pieces to install them, $1,000 plus Doug's headers which basically don't do much and in the ballpark of 800 to $1,000 for MSD ignition which ain't going to do nothing but empty your wallet over a stock ignition.... Add up that $4,000 and what you have for an engine now and sell it and buy a blueprint engine that comes with a Dyno sheet for the horsepower you're looking for...
Drop it in with some cheap headers and stock ignition and light your world on fire....
My-2....
Click to expand...
I like where your going with that actually, however, the Dougs headers are only 550$ and they are one of the only headers that fit an a body without dragging on the ground everytime you hit a speed bump, as well as one of the only ones that you dont have to remove all of your steering **** to install/take off, and my city is full of gigantic potholes...i found that lesson out the hard way on my 70 dart a few years back, As for the msd ignition, i dont know why it costed that much for you, you can get a used 6a box for like 100$ and the blaster coil ext for under 100$ the plug wires are only 100$ too.

That being said, the Crate motor sounds like the good route to go, skip all the BS and work and just sign a check and be done.
 
autoxcuda said:
If there’s no one you’d trust with the basic machine work, who would you trust to port and/or do a valve job on your stock heads?

To make 400-450hp from a 360 magnum, you’ll need a cam that will require a valve spring change from stock.

The old MP crate motors hit 380+ hp. 9:1 compression with M1 single plane intake, and 750 Holley carb. Lots of duration, not much lift so they could use stock rockers.
Click to expand...
would likely ship them out to somewhere who is reputable, but im not paying to ship an engine block Lol.
 
wes beem said:
I like where your going with that actually, however, the Dougs headers are only 550$ and they are one of the only headers that fit an a body without dragging on the ground everytime you hit a speed bump, as well as one of the only ones that you dont have to remove all of your steering **** to install/take off, and my city is full of gigantic potholes...i found that lesson out the hard way on my 70 dart a few years back, As for the msd ignition, i dont know why it costed that much for you, you can get a used 6a box for like 100$ and the blaster coil ext for under 100$ the plug wires are only 100$ too.

That being said, the Crate motor sounds like the good route to go, skip all the BS and work and just sign a check and be done.
Click to expand...
Well boss I've had all these discussions dozens of times over the last 10 years I've been on this forum and they all end up just taking threads like this in a different direction. None of my cheap headers have smashes on the bottom of them because they hang down one inch further than the dougs. (Zero extra performance) Taking the one control arm off the one time you put the headers on isn't the end of the world. (One night off and back on..)
The last customer of mine that bought some eBay used ignition box turned out to be junk...
You spend your money getting an extra inch of ground clearance and take your chances on a used ignition box and I'll buy a stroker kit and we'll see who wins the race...
 
Not disagreeing with you on the stroker, in fact thats probably the route ill end up going, was more just explaining why i have historically run the other supporting parts that i do.

Im not afraid to spend money on the build, but deff didnt want to drop 2200$ on heads if they wont change anything noticable.

As for that 1-2 inches or so of header clearance, it matters where i live, my headers were completely smashed in just going in and out of my own driveway, and the potholes here are 3-5 inches deep and take up entire lanes of the road. I dont see that changing anytime soon as its been that way here my entire life. The Allignment shops love it.
 
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