Cam choice for 318

[Steve Orr]

Hi guys! I need some advice from the experienced, I am gathering parts for a full rebuild of a 318 which I plan on installing into my '74' Valiant Ute. I will be running 3.23 or hopefully 3.5to1 diff, stock stall convertor in a 904, moving to the 318. I am using 1.88in & 1.60ex valves in heads which will be hogged out and polished in the ex side. I intend to have 9.0to1 compression as a minimum with cast pistons, and I am using a TQ along with a 340 cast intake. The big questions is cam selection?? and it's confusing as most are aware from the many catalog's avaliable the spec's appear similar but obviously there is some difference? Help please!! I would like to run in the flat 14 second mark or a tad quicker if possible.
Many Thanks

[451Mopar]

With the stock converter, 9.0:1 compression and 3.23:1 gears I would run the Hughes HE0914AL cam. It specs out with 208/214 duration @ 0.050", 0.458"/0.470" lift, 112 LSA.

This can should give a strong flat torque curve to 4,500 RPM, then start to drop off.
Desktop dyno estimates 286 HP @ 5,000 RPM, 353 ft/lbs torque @ 3,500 RPM with 330+ ft/lbs at 2,000 RPM and 333 ft/lbs @ 4,500 RPM (like I said, a flat torque curve.)

The HE1923AL with 219/223 @ 0.050" duration, 0.489"/0.504" lift on 112 LSA may be OK with the 3.55:1 gears. A looser converter would help also.

Desktop Dyno thinks this cam will make 304 HP @ 5,000 RPM.
You give up some low end torque, shows 307 ft/lbs @ 2,000 RPM.
Peak torque is 347 @ 4,000 RPM so the engine makes less peak torque, but moves the power band up about 500 RPM to make more Horse Power. This is where more gear and converter stall speed helps.

The HE2430AL with 223/230 @ 0.050" duration, 0.504"/0.515" lift on 110 LSA may be OK with the 3.55:1 gears. you will need a higher stall converter with this cam, and it would work better with a bit more compression also.

Desktop Dyno thinks this cam will make 316 HP @ 5,500 RPM.
You give up alot of low end torque, shows 290 ft/lbs @ 2,000 RPM.
Peak torque is 340 @ 4,000 RPM and also at 4,500 RPM (may peak between these two? Like before the engines power band is moved about another 500 RPM up, and you have less torque. Torque drops off to 302 ft/lbs @ 5,500 RPM.

There is a possability that this last cam could actually make your car slower than one of the smaller cams because of the loss of torque, and only 12 HP more than the 1923 cam? It will depend on the rears and converter you use, if the converter is too low stall and the gears are 3.23:1 it will take this engine more time to accelerate into it's power band.

[440Ramcharger]

It sounds like you are putting larger valves in the 318 head. The ports on the 318 head will not match up well with the ports on the 340 style intake. I would find some 360/340 heads and then go from there. 14 flat in the quarter is going to be tough with 3.23's and a stock converter.Is the car in full dress? One thing you have going for you is the 904 has a lower 1st gear than the 727 2.70 vs. 2.45. Good luck and let us know how it goes.

[Fred]

If you have not done the heads yet, try for a set of 318 "302" heads. 1986 to 1991 318 cars had them. Best cast heads for a 318.
They will also except the larger valves.
As per 440Ramcharger the ports on the 318 heads will have a small mismatch. No big deal.
The Edelbrock Performer would be a better manifold.

Fred..

[Doug Wilson]

I don't think you can make the numbers you want with thee combo you propose.