I spent today at the track testing shift points. The weather didn't change much during testing, 11:30am to 5:43pm; so that is helpful. Temp varied from 83 to 88 and then went back down to 84 for the last run (83,87,88,88,86,84).

I made two passes at each shift rpm. The order of the runs was 6500, 6700, 7000, 6700, 7000, 6500.
There was very little difference, so for this post I averaged the two runs at each shift point for comparison:

6500 - 6700 - 7000
5.893, 5.878, 5.876 Eighth mile ET
115.7, 115.8, 115.2 Eighth mile speed
9.333, 9.304, 9.300 Quarter mile ET
141.9, 142.2, 142.3 Quarter mile speed

One of the 7000 rpm runs had an unusally low 1/8 mph, and that effected the average. The other 7000 rpm mph was higher than all the others, so it had the highest and lowest. So the 1/8 mph number may not be worth using.

I guess 6500 is too low, but the difference between 6700 and 7000 may be too close to call.

Thanks for the comprehensive info Jim, as Always

IMO, shift points no doubt will depend on the engines HP sweet spot. So the sweet spot will be different with most engines, but still within 1000 RPM for 90% of us 6000 RPM to 7000 RPM IMO

While I havent done much testing, IMO I think there may be an advantage to Dual shift points between first and second/third.

Since the first gear is the best Multipling gear , I think a couple hundred RPM above the sweet spot may be beneficial on the 1st to 2nd shift compared to the 2nd to 3rd. shift point.

Or not, mike

What happened to +7500? Oooh its a wedge, sorry.

Just teasing. Looks very fast! I have not seen any wedge motors that fast at our local 1/8th in a while.

Good post Thankx Jim

In both cases ( ET and MPH ) the change is less than 1% - and with only 3 points to look at -

Jim with my 10.0 set up a couple hundred rpm's are
worth right at .020... thats with a mech throttle stop
on it so its not a apples to apples test... it ran a
string (7) 10.00 and then Doug stretched the rpm and
ran a 9.98

Curious, what does it go through the lights at in the 1/4 on the 7000rpm shifts vs the 6700rpm shifts?

My flat tappet 500 really had its tongue hanging out going from 6800rpm shifts to 7000rpm shifts. It definitely wasnt worth it in my case. Of course my sled is a touch heavier than yours too.

You mind sharing those cam specs again? I know they have been posted before, but I dont remember what they were.

I had been running 4.30 gears for the last few years. However, a couple pinion teeth broke a couple weeks ago, so I put my old 4.56 gears back in to get me through the rest of the season. That was one reason I decided to go through the shift point tests.

At 142 mph, the tach read 7150 at the finish line. Since all the runs had very close mph, the rpm was the same. With the 4.30 gears it was about 300 rpm less.

The cam is a Comp Cams shelf grind, MM-305S-10:

305º/320º@.020", 279º/287º@.050", 197º/200º@.200", 0.650"/0.630" lift published (0.690/0.670 with my 1.6 rockers), 110 LSA. I am running 150 lbs seat pressure and 440 open with EDM oiling flat tappets.

My 500 Indy headed Engine likes 6900 but any less then that it will start to slow.

Curious Jim, what converter setup do you run in your car?

I have a similar setup with 4.56s, 32 tall tire and at 138 MPH I am crossing at about 7150 just like you in the weather we have now.

Mine's a glide with a 8 inch ATI.