Worth the change?!

Ok, so try and hang with me for a minute.

So I have a '64 Dart. Its latest setup was a 360/4spd/8.25" 3.55 SureGrip that ran 8.60s in the 1/8th mile and was very drive-able. This wasn't enough for me, so I've since pulled the entire drivetrain out front to back with plans of a 340/416 stroker with a 4spd and 8.75". This leaves me with a perfectly good, low mile 360/4spd/8.25" with 3.55SG setup laying around.

Enter, my '70 Duster. So early this year I acquired a '70 duster 318/904/7.25 car that is overall decent, but the drivetrain is garbage. So the obvious thing to do is put the Darts old drivetrain into the Duster, 4spd and all.

The 360 in question is a
'70 360 +0.060"
SpeedPro H116CP pistons measured 9.3:1cr
587 heads as cast 1.88/1.60 valves
LD340 with a Street demon 750
CompCams 268AH10 with matching springs
340HP exhaust manifolds


So before it goes in the duster, I'm gonna freshen it up a bit. I have, on the shelf, a CompCams 484PP cam and a set of 2.02" intake valves.

Would it be worth it to throw in the choppier cam and bigger valves, if I plan on keeping the 3.55 gears and HP exhaust manifolds?

I would keep what you have and add new valve springs. The 484 cam is nice and I've run mine with 3.23 gears and 27" dia. rear tires. Never used 4th around town. Also, it was the MP brand so CC might be friendlier. Add the 2.02's or keep the 1.88's and pocket port the heads if not already done.

If it went 8.60’s in the Dart, it should go 8.70’s in the Duster as is. Unless you’re gonna zing it up over 5500 rpm regularly, the bigger valves won’t help any. Use the HP manifolds in the Duster, and get you some TTI’s for the Dart. I’d make the Dart the ground pounder, and the Duster would be the get in it and go anywhere car. Just my 2 cents....lol.

I would shift at 6000rpm with the 360 as it was. I thought if I added the 2.02" valves, 484PP cam and some ARP rod bolts for a little safety measure, I could maybe add 30hp up top and turn it to 6500rpm. Maybe get the duster in the 8.40-8.50 range.

I do wanna keep the Duster street friendly so I can enjoy it on a near daily basis. That's where I'm mixed on the bigger cam.

My suggestion is to keep the engine as is with the exception of popping the heads off and mildly port them as well as a gasket match and a good clean up of the casting flash in the ports etc.
That would make for a good daily driver type car.

Stage 2 would be to do the head work and install the 2.02 valves in them, and the bigger cam (with matching springs) only if you plan on running long tube headers.
The higher you plan to rev the engine and the more flow you put through it, the more headers will help.

Sure, you will see a lot of gains with Stage 2 if you keep the stock manifolds, but they are a bit of a cork in the system if you start revving it to 6,500 r.p.m. as you say you want to unless you extrude hone them an that's a lot of $$$.
I would hazard to guess about 40 H.P. is lost.

Have fun, and let us know how it turned out!

Daily driver?

Leave it alone. 2.02 takes port work by someone who knows what they are doing.

That 268 cam isn't making any power above about 5300-5400 in a 360 like yours. You're just killing it with RPM. Shift at 5300-5500 maybe 5700 and see if the car picks up.

Had a similar set up in a 71 demon, it ran 105-107 mph in the 1/4. Never shifted above 5600.

Unless you're planning on tubbing the dart I would put your biggest drivetrain in the duster which has much more generous allowances for bigger rear tires.. spinnin ain't winnin....