I was wondering if a TH350 (bone stock except for deep pan) hold up to 5500RPM(engine) in 1st gear?

I'm wondering this because my MPH in the 1/8 is 70.25. With a 28 inch tall tire, and 2.73 gears, i think the engine would be at about 5500 at 70mph with the TH350's 2.25:1 gear ratio.

See, my engine probably tops out at 5000RPM or so, but if a shift the engine into second gear, I'll end up with only 3500RPM@70ishMPH.

But wouldn't i want to be close to my peak HP on the top end?

I'm tempted to try this but wouldnt want to blow up my tranny.

I know i should get a 3.36 or 3.55 gear to help some, but I just wonder if the tranny would hold up to it.

According to my MPH, i'm only making some 260HP if that matters.

Also, what's the correct burn out procedure with a TH350?

Unless there's something wrong with it, I don't know why it would hurt it. I'd be more worried about your motor than your tranny smile.gif . You have a 307 or a 350? I know my 307 would never even make it to 5500, and if it did I'd be picking parts up off the ground! It doesn't make power past about 4800 any way.

To do a burnout, drop it down into 1st so it won't shift, get the rear wheels in the waterbox, and apply the brakes very lightly. Give it a good amount of gas, and increase your braking pressure just enough to keep the car from moving. When the tires start spinning, just modulate your rpms with the gas pedal so you don't over-rev the motor, and use the brake pedal to keep the car in place until you've roasted em. graemlins/hurray.gif

Run my TH350 to 6400 rpm 400 times per year. Its not the rpm's that limits the 350 its the hp, and maybe a nice hard trans brake hit. For the burnout drop the trans into first and get the tires spinning, then shift to second. As soon as you see smoke off the tires ease off the brake and the gas, but don't let the tires grab hard, because this is what causes sprags to break.

Here is an article (http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=28;t=005502;p=2) that discusses burnouts and other trans issues. Jakeshoe's post, very long but worth reading, is down the page a bit.

Originally posted by Slowpoke70:
I'm wondering this because my MPH in the 1/8 is 70.25. With a 28 inch tall tire, and 2.73 gears, i think the engine would be at about 5500 at 70mph with the TH350's 2.25:1 gear ratio. I'm guessing you dis-lexed the 1st gear ratio :D
..its 2.52 1st gear/TH350
If you stay with 2.73's,you need a shorter tires..no more than 26" tall..like a 235/60/15
The taller tire "kills" the 2.73's..its like having 2.56's with a short tire graemlins/sad.gif
And try not reving it too high in 1st..the 2.73's become counter-productive,at least in my combo,if I shift too high..car goes quicker shifting at 4800-5000 than at 5500

LOL, i did my calculations with the 2.52, i just typo'd it here.

Anyway, It is a 350SBC 2blt mains, stock bottom end, cast pistons, etc. My whole combo can be found here http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=4;t=021087

Enrique, my 66, when it had the TH350, would shift itself at 5500. Never had any problems. You shouldn't either.

I took mine to 6000-6200 for 2 full seasons of racing then some and several miles on the street, a 350 is a good trans with a shift kit,cooler and deep pan.

Your stock Turbo 350 should be fine. My son is running a beefed up ATI, Turbo 350 behind a 540 Big Block with a little juice (9.40s @ 147). The apparent weakest link is the sprague but will be fine as long as you come out of the burnout off the gas peddle, as freewheeling then suddenly getting traction is what breaks all Turbos (350s and 400s). With your power level a burnout may not be necessary and might only add extra heat to the engine and transmission. Do you have a posi-trac?