[TAtech]

Originally Posted by TAtech

I agree with the .64 od gear being useless unless running faster than 80 mph. I built a large displacement aluminum hemi, 800 hp large cam for a 68 Doge Dart several years ago and used the TKO600 with the .64 od using a 373 diff. gear and hated it. I was going to change gear to 488 but car was sold before I got around to it. I personally would not consider anything higher than s 410 with a .64 od.

Forgot to mention it was s 28" tire

[LeighP]

My 68 Firebird with 428 and RAIV cam runs a TKO-600 with a 3.5 rear gear. Overall, the gearing is perfect for the first 4 gears. 5th requires me to be doing 50mph minimum to use. On a highway at 70mph, its terrific.

[Formulajones]

In every case I've seen like that, tuning cures it.

With large overlap camshafts, the idle to main circuit transition is critical, along with power valve all has to be custom modified for smooth transitions so the engine isn't bucking and complaining at low rpm speeds. This is where you toss the wide band out the window and start giving the engine what it wants.

The distributor is also key, primarily the vacuum advance mixed in with the initial timing and low rpm curve to give the engine the right amount of timing to be happy in those conditions.

TAtech didn't give enough information but in your case Leigh, a 428 with a RAIV cam would be really easy and should practically idle along in 5th gear once everything is happy together. 230 @ .050 on a 113 or 115 LSA like a RAIV cam is, in a 428, is a pretty mild camshaft, providing it's installed around 108 ICL and not retarded.