[olddog]

I have a 347. Cam duration is I/E 236/242 @0.050" lift is 0.555/0.575" LSA is 106 or 108. All this is from memory. It has Edel performer RPM heads. Gasket match appears to have been done to the ports. It has Mass Flow EFI, which is a Edel Victor Jr single plane intake with injection bungs welded into it. According to desk top dyno programs it should be in the 400 to 450 hp range, but I feel it is more like 350-375. I need to chip the EFI and work on the tuning. I'm quite sure there is more in it.

By the seat of my pants, it pulls strong all the way to the rev limit of 6500. A 302 would have the same mean piston speed at 7400 rpm. I would say it is close enough to maximum torque that I cannot feel any difference by 2500 rpm. Again a 302 would be there by 2800.

The cam does not smooth out until about 1800 rpm. That would be about 2040 rpm in a 302. Now do to the tuning issues mentioned, at light load lower rpm it is pulling in too much timing. It may smooth out a little sooner if properly tuned.

I have a TKO-600 transmission with the 0.62 5th gear. I had a rear end ratio of 3.5:1 and just changed it to 3.89:1. I like the lower gear ratio much better, all the way around. However I would hate it with a 4 speed, as 60 mph is just under 3000 rpm.

I can be in 5th gear at 1500 rpm and can accelerate up the steepest hills I can find, with ease. So the low end torque is not bad.

So in short, my engine with a 3.0" stroke should be fairly close to what the OP is wanting. I think it would be workable.

I do think the gear ratio he mentioned is way too steep. I would shoot for about 2500 rpm at 60 mph, to keep the noise reasonable. Maybe a little less, but this is going to kill performance. I would strongly recommend a 5 speed. Gearing is going to make a big difference for this engine. If you gear it too steep, it is going to be a dog!

I have no hint of valve float at 6500 rpm, but I seriously doubt it would turn much more. It does have aluminum roller rockers. You will have to have good stuff to get to 8000 rpm.

If you go to a 4.125 bore aftermarket block, that should help the torque a bit, and it will improve breathing on any head by un-shrouding the valves. 321 cubes isn't all that far short of a 331. This should make you happy. When you see some of the 5.0 blocks that have split in two, a better block is a great idea for turning 8000 rpm.