Critique this combo - 318!
I've been trying to zero in on an engine build for a while now using Desktop Dyno as a guide. I put in as much info as I can, especially published flow numbers for heads to make it as accurate as possible.
I've come up with what I perceive to be a nasty street/strip combo but naturally wanted to hear what others think. Goals for the car are to putt it around for ice cream and cruise nights but also drive it to the track, run it to low 12's and drive it home. Guess I'm willing to put up with whatever inherent drivability issues there are with a 'big' cam, loose converter and steep gears.
Car is a '71 Dart, lightened, but will be installing frame connectors. Hoping to get it down to 3,050-3,100 without me.
Here's the specs on the engine:
318 bored .040" over, 3.950" bore. '67 casting. (thick!)
Stock stroke, 3.31" (318-3 steel truck crank)
RHS heads, 1.92" intake valves
Hughes 1.6 rockers
Smith Bros. pushrods
KB 167 Hypers, 5 cc piston volume. C.R. works out to be approx. 10.2:1 with M.P. thin head gasket (.025") KB's web calculator says 8.8 dynamic compression if that matters to you. These come w. 2 5/64 and 1 3/16 rings and a 984 pin. No coating that I'm aware of.
Holley Strip Dominator intake
6139 TQ, (small primaries, 800CFM).
TTi headers, 1 5/8" primaries, full dual exhaust.
Mopar elec. dist., MSD 6
Mech fuel pump
Comp. 282s - 282 adv, duration, .495" lift, .528" w. 1.6 rockers. LCA 110, Intake CL is 106. Not sure what it would be installed at, probably between 2-4 degrees advanced.
Machine work planned: square deck block, index crank, line hone mains, bore and hone .040" over w. torque plate, recondition stock rods w. new bolts, deburr block, intall new bearings (possibly coated). Possibly may bush the lifter bores, just trying to get everything square and equal.
Plan to CC heads and ensure chambers are correct @ 62, check I.H. on springs, not sure if I will need longer valves, undecided on valve springs. Cam requires Comp. 995-16 which are 115 lbs @ 1.7".
Car will have a 4.10 rear, low gear 904 w. shift kit. DD shows torque peak for this combo @ 5,000 rpm, converter might end up around 4K+ unfortunately, not so great for the street. Oh yeah, 27" tires.
May consider picking up an Air Gap and a Holley Ultra Series 750 rather than the TQ and Strip. Dom. which i already have.
Basically just want to hear what people think about this combo for my intended goals.
Whew!
Thanks,
- Greg
Beware, the 67 casting usually isn't thick, the 68 up to about 72 are tho....
Look carefully at the crank, -3 trusk engines past about 70 usually had dish pistons and cast cranks..
Please get Forged pistons, no use spending all kindsa dough and using hyper pistons. Yeah yeah, I know, so and so has ran them 2400 runs at 9200 RPM, with no issues....... but when the bore wears, the skirts like to migrate to your pan, and face it, good exhaust and flat to the floor, it's hard to hear it ping, and I have seen pistons become see through in one pass.
With the cam, and the small cubes, I would go Performer RPM, or a worked over street dominator. For a 318, your cam is in the dual plane range. IMO
TQ??? Really? Nothing like leaving HP on the table. (thinking maybe one of those cool holley ofshoot carbs, or even a 750EB, before a big ol thermobog) Good carb for the street, but, squareish bore feeds the cylinders fuel more equally. Anyone who has pulled the four corner plugs while tuning knows thiis.
I'm thinking a voodoo can about the same size....... But, Just like the hyper pistons, I don't trust comps in my motors, not even a stock motor. The ol 260/260 I used to use tons in my stock rebuilds, but after a few lobes dissapearing..... Nahh.
With that cam, if you really get a stall speed of 4K, your probably about 1K under your peak torque, and take it from someone who ran a 318 with a 3500, drop her in gear and the car wont move, 4.88 car. 3500 stall in a short stroke SB equals HOT trany temps, and slippery times in the rain, hehe. (and 5MPG) *4K in say, a 440, almost will feel stock at low throttle settings, because of the greater torque of the motor)
Make sure the rods are the old floaters, the old 318 rods were pretty strong, and lighter than the HD 318 rod. (*Stock 360 rods were called the HD 318 rod in about 72, I am guessing to save money)
And, again, all my opinions are exactly that, opinions from a 318 guy, who has built many many many of them.