APRIL HOT ROD; 360 Magnums

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Bill Dedman

Bill Dedman

bill dedman
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Pretty informative article on (their opinion) low-dollar hop-up of a 360 Magnum 300HP crate motor in the April 2008 issue of Hot Rod.

Basically, they flow-tested stock heads vs. Edelbrock alum. heads, and then dyno-tested a 300HP crate 360, and then replaced the cam with a .565" (!)-lift Comp cams modeaate-duration bumpstick, and installed an M-1 single plane manifold and a 750 Holley-style carb (Demon?), adding Edelbrock aluminum heads, since the stock heads will run into trouble at valve lifts much over .500" (valve giude boss interference.) My cam lifts .525" and works okay with those heads, but I think it's at the limit.

They picked it up 125 HP with those 3 items (cam, heads and intake/carb.)

Interesting article. The flow information on the two differeng heads was particularly interesting, I thought. The stock-type cast iron heads were assembly-line items, not the R/T. Intake flow was only a shade over 200 cfm... I think the aluminim version from Edelbrock beat the stock heads by somehing like 50 cfm., which is about 25 persent.... Impressive, I thought.

Now, I have to start saving for some... damn....

Bill, in Conway, AR
 
T THOUGHT that information looked familiar...

Thanks for the heads-up!!!

Dang... I should have recognized that...
 
Bill Dedman said:
Interesting article. The flow information on the two differeng heads was particularly interesting, I thought. The stock-type cast iron heads were assembly-line items, not the R/T. Intake flow was only a shade over 200 cfm... I think the aluminim version from Edelbrock beat the stock heads by somehing like 50 cfm., which is about 25 persent.... Impressive, I thought.
Click to expand...


The original 300HP and 380HP crate motors had stock production heads. These engines typically dyno'd in the 320 (and confirmed in the article) and slightly over 400HP. When they stopped installing magnum engines in pick-ups and vans the crate motors switched to the magnum R/T head. These engines are advertised as 320 and 390 HP. Haven't seen any dyno numbers on them but you can expect them to be better than the crate motors with stock heads.
 
Dave,

I have some third-hand innformation about the REAL output of the later R/T-head equippes "390" HP crate 360 Magnum.

Like I said, it's third (or, fourth) hand...

I have a friend here who just installed one of those R/T-headed
"390-hp" 360 M-P crate motors in his '69 Dart GT. He did some research before buying it and found one source that said tthat with 1 3/4" headers and a 750 Holley, it made 414 HP on an independent engine dyno...

Sounds about right to me... Feels like a mid-to-high 12-second car in that Dart, with TTI headers, a 3,400 rpm stall converter and a 3.55 Sure Grip.

With a 4.10 gear, a GOOD limited-slip, or spool of some sort, and some GOOD slicks, 12.60s should be possible, I think.

Just my 2-cents'....

Bill
 
Dave,
When the weather gets a little better around here, we'll find out. I think he's getting some slicks for it, as we speak...

There are no quarter-mile dragstrips in Arkansas any more, but we have several 1,000-foot and eighth-mile facilities from which to choose.

We can take those times and project them to a quarter-mile number, no problem.

I'll let you know when he takes it to the strip... and, he will... :)

Bill, in Conway, AR
 
Really sorry for the delay in answering this question. I have been sick, but am on the mend, now. My apologies.

I am running some very slightly pocket ported Magnum (otherwise bone stock OEM) truck heads using back-cut valves with a 3-angle valve job.

I squeezed by on the cam lift just barely; my cam is a Hughres grind that they no longer make any more, but it had .525" lift, on the intake, and that ran the valve guide boss really close to the retainer, but there was no interference, so I used it... but that is the limit. Any more lift than that and I'd have had to machine the bosses that protrude up out of the cylinder head toward the top of the valve stem. I don't know whether the R/T heads have this limitation; I would hope not.
 
A while back, when they first came out with the 360/380 HP engine, a few fellas installed this engine into an A body car that has the track on it's mind, not street.
Reported times I have seen have been as low as 12.2 or 12.02 when the car is built around a 1/4 mile at a time. A street car should perform as you predicted without to much trouble or mods.
 
It was in Mopar Muscle about 2 yrs ago..but they used the LA version of the Eddy heads with hydraulic roller cam also...made right at 450 hp also.
 
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