Maximum torque at low rpm

[artr8]

Background:
1984 D250 with 318, NP 4 speed, 3:7 gears in Dana. 4300 pounds, 60k original miles.

Goal:
Maximize low speed engine torque for tow. Not exceeding 4300 rpm. Keeping fuel system.

Parts available:
Headers, long tube
Stock manifold
2-1/2 exhaust, dual
1984 318 short block flat tappet, can be machined for roller
1994 360 magnum short block
340 spec cam flat tappet
360 roller cam stock magnum
262XE cam flat tappet
360 magnum heads
318 magnum heads
318 EQ heads
318 heads, 1970
360 heads, 1972
2 bbl stock 318 intake LA
Edelbrock 318/360 intake LA, spreadbore
Edelbrock air gap intake magnum, square bore
2 barrel Carter bbd
4 barrel Edelbrock 600 cfm
Thermoquad
4 barrel Holley 600 cfm

With the goal of max torque for tow, how would you combine the parts?

 

[Don Frelier]

All the 5.9 magnum stuff with the airgap intake.
And yes I would use fuel injection but you would need to create a fuel system for it.

 

[pnora]

Better recheck that axle ratio.

 

[dvw]

318 Magnum heads, 360 Magnum short block, long headers, smallest duration roller cam, T-quad.
Doug

 

[artr8]

I will let this run over the weekend and review thoughts on Monday.
Reminder: Engine upgrades only, fuel delivery will remain carbureted.
Exhaust, cam, heads, intake, carb, block are allowed in your response.

 

[pnora]

I will let this run over the weekend and review thoughts on Monday.
Reminder: Engine upgrades only, fuel delivery will remain carbureted.
Exhaust, cam, heads, intake, carb, block are allowed in your response.

You still should check that rear end and its ratio. I do not recall a 3.7 ratio from the factory. Knowing the correct ratio may help on your overall plan.

 

[Photon440]

If you weren't stuck on those carbs, an Edelbrock AVS2 650 would be better than the others in the low rpm range (1800) for torque due to its annular boosters.

 

[59pwrwgn]

I think Hotroddave over at Moparts was doing write ups about this before he moved on to 3g hemis. You might try looking a some of his old posts.

 

[artr8]

318 Magnum heads, 360 Magnum short block, long headers, smallest duration roller cam, T-quad.
Doug

Seems to be my best choice. Appreciate the input.

 

[artr8]

First change in place. Finished headers to 2-1/2 dual pipes. Single muffler with 3 inch single out.
Did a 40-75 punch with original exhaust, 30 second average on two runs.
Same trial, after exhaust upgrade, same conditions, 20 seconds.

 

[Photon440]

First change in place. Finished headers to 2-1/2 dual pipes. Single muffler with 3 inch single out.
Did a 40-75 punch with original exhaust, 30 second average on two runs.
Same trial, after exhaust upgrade, same conditions, 20 seconds.

It used to take half a minute to go from 40-75? What were the 0-60 times like? Good improvement though.

 

[artr8]

40-75 is consistent. 1:1 drive to the 3:55 axle. 0-60 would require consistent shifts on a truck 4-speed. NP. Not the smoothest shifting transmission but it is tough.

 

[1967coronet]

I'd use the 5.9 mag engine and heads, with that engines correct cam set.
Put the eddy spread bore intake on and the thermoquad plus the headers.