i got the cam specs for it if you want to put them into the desktop dyno. it has a 458/484 lift, 260/270 duration, and has a power band from 1200-4800rpms. is there anything more you need? I can believe the 455ft-lbs of torque, but the 284hp seems way off, especially since a 68' 390 truck motor had about 260-270hp with stock cam, stock intake manifold, exhaust manifold, and single exhaust. i have a bigger lift cam, a medium riser intake, 2"carb spacer, headers, and dual 2.5" exhaust.

 

Remember, back in 1968 they rated 'em with GROSS hp. Even then, I think they were optimistic.

And yes, I need the valve timing, at the seat (usually listed as .004" lift). IVO, IVC, EVO, and EVC.

Its your heads that are holding you down. Well, that and the cam. The stock FE cam is actually better than the Edelbrock Performer cam.

I ran the bone stock 390 truck motor and came up with 246hp @ 4000rpm, and 366ft-lbs @ 2000rpm. That sounds about right.

With your setup and a stock FE cam, I get 303hp @ 4500rpm, and 438ft-lbs @ 2000rpm. The stock FE cam isn't really that bad IMO, aside from being 30+ year old technology. FWIW, it was a 256/266 degree dual pattern cam, with .427"/.431" lift.

But yeah, get me your cam specs.

 

the machine shop looked up the stock cam specs and got a .420 lift. I'll get the rest of the info on the cam tomorrow.

 

Rusty, those cam specs sound like the Melling torque series or like the SSI PAW cam specs.

 

Nope, I got 'em off this board a while back. Just to make sure, I looked in my book. Lift is listed at .427"/.431" for '68-'76 360's and 390's in trucks.

 

IVO @ 24 BTDC (.005 LIFT)
IVC @ 56 ABDC
EVO @ 69 BBDC
EVC @ 21 ATDC

IVO @ 8- BTDC (.050 LIFT)
IVC @ 22 ABDC
EVO@ 37 BBDC
EVC @ 13- ATDC

CAM DURATION 260/270

 

Ok with that cam and the rest of your setup, you're looking at 304hp @ 4500rpm, and 439ft-lbs @ 2000rpm.

You could install it 4 degrees retarded and pick up 9hp.

 

torque figure seems about right, but i'm still not sure about the hp figure. comparing the the figure you just gave me to the one you had above that with the stock cam i only get a 1hp, 1ft/lbs advantage, which does not seem right. i have .031/.053 more lift than the stock cam. i think i should still be between 350-400hp range.

 

No, the hp figure is right where it should be. A 390 with a Crane 343941 cam, about 10 to 1 compression, and PORTED heads will get you about 380 - 400hp. With your mild cam and unported heads you're at about 300hp. Sorry, but that's just the way it is. The heads choke it up high, limiting your horsepower. The torque is still there down low though, due to the mild cam.

FWIW, DD2k is known to be a bit optimistic, but I used actual flow numbers from unported stock heads in the simulations. It should be fairly close.

If you want more hp, either port your heads or get a set of ported heads. A bigger cam will help a lot too. FE's respond EXTREMELY well to porting the heads. By simply porting your heads you'd be up to 354hp @ 5000rpm, and 440ft-lbs @ 3000rpm. The torque curve is flat as a pancake up to about 4000rpm, where it starts to drop off.

Also, I think DD2k is optimistic with the stock cam. It doesn't take into account that it's 30+ year old technology. But still, your cam is very mild and very close to stock. It's not so much the lift as the duration. And even then, it's not too much bigger than stock.

 

do you have a line graph of the hp and torque figures, i would like to see them to see how my engine performs on that graph.

 

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