300 HP 360 Magnum Crate Motor Upgrades

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Michaeluser

Michaeluser

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Well being a landed a smoking deal on a slightly used 300HP Mopar Crate 360 I was wondering what could I do to bring it up to the 380 Hp version that was available at the same time this motor was introduced.

I am getting ready for to get the 1973 Duster going and wanted to tear into the motor before I clean it up and paint it. If the cam is the only difference then it's a no-brainer.

The specs are:
Part # P5249498
Horsepower: 300 @ 4750 rpm
Torque: 375 @ 4000 rpm
Compression Ratio: 9.0:1
Block: Cast Iron
Crankshaft: Cast 3.580" Stroke
Heads, Chamber Size: Cast Iron
Valves: 1.925" / 1.625"
Camshaft Lift: 0.512" / 0.512"
Dur. @ 0.050": 238 / 238
Intake: M1 Aluminum Dual Plane


The 380 HP
Part # P5249499

Horsepower: 380 hp @ 5300 rpm
Torque: 410 ft-lbs @ 4400
Compression Ratio: 9.0:1
Block: Cast Iron
Crankshaft: Cast, 3.580"
Heads, Chamber Size: Cast Iron
Valves: 1.925" / 1.625"
Camshaft Lift: 0.501" / 0.513"
Dur. @ 0.050": 288 / 292
Intake: M1 Aluminum Dual Plane


The cam is the only difference I can see. Will the cam add 80HP. Please chime in.

Thanks
 
Swap on a single plane(M1),or a Edelbrock rpm air gap.Call Bullitt crower or comp cams.Order a grind with [email protected] on a 110 to 112 lobe center,call Hughes for matching springs.That will get you 400 h.p. You want another 60 to 80 hp,Send ou812 a line,he does a awesome set of rhs heads that will flow 500 plus h.p of airflow easy.
 
According to what I've found on the web, the Mopar 380hp crate motor cam specs were:
288in/292ex advertised duration
230in/234ex @ .050
.501in/.513 ex lift
I don't have specs on the Mopar lobe center.

Oh yeah, my 380hp crate motor came with a M1 aluminum single-plane intake manifold, not dual-plane.
I haven't run mine yet, it came with my '69 Dart project when I bought it a couple of years ago. Even though it's new, I still want to tear it down and check the clearances before it goes back it the car after paint.
 
Thanks all that sounds great. I will check those out.
I would be happy with a straight cam swap and manifold. The Air Gap is a nice piece.

OCDart where do you live? Have we met?

Thanks again.
 
Hot Rod has a great article for 412 HP under "Junkyard Jewel" for this motor.
Good to know deals are still out there on these original motors. Prob. Very very few these days. I got a barn find new 380 HP 2yrs ago now in my 73 Duster.

Do the upgrade if you can as at the car will SCREAM. Last summer a guy was selling a 380 hp at Carlisle for 2k.
 
Great little article. I got the motor for $1500 plus 904 trans (sold) and carb and cast manifolds. Thanks to Craigslist... I want to keep it easy and not put new heads, just a cam and rocker with a new intake manifold. I think it should do well for now.

Thanks
 
Lobe center on a 109.I went 224@ .050,.491 lift on a 114 lobe center.Advertised is 284.I get a 340 cam idle,with 21 inches of vacuum at 900 in park.Head flow peaks at .480 to .500,depending on how clean the stock castings on the engine are.
 
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