New trans is in order.

So, last weekend of the year, and my 904 gave up the ghost coming out of the burnout box on Saturday morning. It appears that the sprag called it a day, but we won't know until it gets yanked. At least that gives me a reason to up the ante on the converter. I'll step up to one that can flash to over 5000. The current unit will hit 4700 on the t-brake, but only flashes to 4000 when I footbrake it, and the t-brake is worth a tenth in the 60' right now. What are people's thoughts on the value of a 2.74 low gear behind a 360 that makes modest amounts of torque in a 3000 lb car? I am running a 5.13 gear already, so I would think that adding 12% more gear along with another 1000 rpm of converter should really make this thing leave.

It will make the 1-2 shift worse (higher RPM loss), but I would guess the converter would take care of that?

Good point. I know that it means you spend more time in 2nd gear. I'm pretty much 1/8 mile racing now, so that's a factor to consider.

The real concerns I know of is the chassis ability on holding the lower starting line ratio without spinning
I swapped the standard 2.45 low gear ratio in my old NHRA 415 HP M.W. 727 stocker to the Mopar 2.77 low gear helical cut gear set, I also swapped the rear gear ratio from 4.89 to 4.56, those changes help that car(3520 lbs. with the driver)on nine inch slicks a long time ago
if your low gear was 2.45 ratio your starting line ratio with the 5.13 would = 2.45X5.13 compared to 2.74X5.13
The car will spend less time in low and second gear and more time in high gear with the lower 1st and 2nd gear ratio
If you have good traction now do the swap , if it is not real good pass on it

Hey Cab. Our track has a really good starting line. The guys do an excellent job. I'm fairly confident the traction will be there foot braking it, but it may be dicey off the t-brake. That said, I can still move my instant center around and see what happens. I've also never played with shocks, so there's that.

Good point.

Something way wrong elsewhere if there is a tenth difference between the foot and the brake.
I have never seen any difference to speak of either way, same 60 foot either way if convertor is correct for the build.
Regards flash, the convertor flashes only one way/ amount
. Drive at 10 Mph in the pits in high gear and whap the throttle. Watch the tach, where the needle jumps to is the flash. You might be talking about the rpm you can hold the car with at the starting line before it moves foot braking.. That will definitely be less than the flash. Its supposed to be. Its a combination of how good your brakes are, front tire size, how loose the convertor is, etc. Lots of factors. Some/ many cars actually work better launching off the foot at a lower rpm( like 1500 or 2000) because the suspension is more “ relaxed” or you get a better run at the convertor. Trying different launch rpm can be used to dial in reaction time too.
Light 3000 pound car i wouldn't bother with a low gear. Get the convertor right, it will 60 fine. It spreads out 1 st and second gear to much for my liking

That is my feeling as well. A 5.13 rear gear and tires around 30" or less tall is plenty of starting line ratio. Converter.

The correct converter is worth way more than correct SLR. The SLR has to be pretty far off to affect ET if the converter flashes to the correct rpm for the combo. I’ve had the wrong converter kill ET anywhere from .10-.60. Made plenty of gear swaps from 4.10-4.88 with various combos that didn’t do squat.
Doug

I agree, the converter is key.
Also: if you change both you can't compare them as to effect.
Leaving the stock 1st gear means you don't need to adjust your shift point.

Hey, thanks all for the input. I see where going to the 2.74 gear may not be the most bang for the buck. Now, as for converter flash, when I footbrake the car, I have found the best overall launch to be about 1200 rpm of pre-load. More rpm against the brake makes the car react quicker, but the 60 ft falls off, as does the ET. The converter stalls to 4500-4700 rpm on the brake. However, my in-car videos show a 4000 rpm "flash" when I launch off the footbrake. The tach only hits 4k on the hit, and that's all. I suspect that's why the 60 ft improved dramatically going off the t-brake. That leads me to think a lot more converter is in order.

I’m interpreting that to mean it flashes higher on the trans brake, than the off idle launch. Do you have video of the 2-3 flash?

I do have video. I've tried posting to here, but that ain't workin', so...
What should I look for on the 2-3 shift?

I’ve always had the best non-data recording era info, by watching the 2-3 flash. There’s zero wheelspin and maximum loading, thus, you can see the fall back after the shift, then the resulting true converter flash. I hope you get it figured out.

Best I can see in the video is shifting at 68-6900 rpm, the 2-3 shift drops back to right about 5000.