how much diff would 1/4 mile times be diff if any? i know the 700 has a steeper 1st gear but enough to make much differance?oh its behind a l69 305
thanks for any replys

 

43 views and no one knows the answer?

 

The TH350 should be better since it takes less hp to run it and there isn't the huge step between 1st and 2nd gear.

 

I can't speak to that exact swap but, I have personaly seen 1.2 seconds(12.34 to an 11.15) going from a 700 to a power glide in a 1st gen. I would think the 350 would pick you up GREAT deal. With no other changes.

 

Having made different comparision tests and others that I know having done this also, have seen about a one mph gain and a 1/10 drop in ET when going to a TH350 from a 700R4/4L60E unit. But this slight gain is not a good tradeoff for the loss in gas mileage, noise, additional rpm, etc.

 

thanks for the replys guys,im going for the swap,just because car is only drivin less then 1000 miles a year, and the cost is better for me

 

Wise decision.

 

i know it sure is a hell of alot cheaper to build a th350 to hold power than it is a 700r4. i bit the bullet last year and swapped mine. i miss the car as my daily driver since the 4100 stall converter and 4.56's with the th350 means no real street time anymore, but it was a good choice overall, i guess

 

Nice thing about a th350 is now you can have a trans brake and that will forsure knock some time off your 1/4 mile slips!

 

not necessarily. the transbrake will require more power to really be utilized well than his l69 can give it. i have a decently quick 305 in my car and i have a t-brake. car is consitantly .05 slower to the 60' and ~.1 slower on the big end. that is right now though. i'll be going to a slick over the drag radials this season, so we'll see if that does anything for me.

 

I dont know about times but I gained 12hp/2tq from the swap. 700r4 with a HD stall to a th350 with a very loose 3000 stall.I have a 2400 holeshot that I think I will find some more power in.

 

I think it would lose et--not gain it.

Less torque multiplication---less jump off the line.

My friend swapped out a powerglide in a 67 RS to a TH-350 and gained 0.7

 

i have the same question. i have a stock 305 in my 88 camaro. my 700r4 is about to go out. no second gear now. also no overdrive. i am thinking about putting in a th350. anyone know what that will do? HP, TQ. also im going to put in a smallblock 350 soon. and then 4.11 gears. any idea. concerns. pros and cons.

 

your gas mileage would take a huge hit--your engine would be screaming at highway speeds. Stick with the 700R4

 

ok. but i want my car to go faster. and i can't use my transmission for much longer now.

the th350 i would put in would be a 4 speed auto with overdrive. so really it wouldn't scream on the freeway. it would be a little faster. and if i add the 4.11 gears then i would accelerate a hell of a lot faster. then throw in a built small block 350. now how is that a bad idea besides the fact gas will suck. the car will be faster than ****. i think the gears are going to wait a while till i can fix my body and other stuff on the car. but after that i would put them in.

ok sooo now. is it a bad idea or not

 

Unless you change the rear end gears--it will be slower

Unless I totally misread your post--you have some serious errors---A TH-350 is a 3 speed automatic

yes

Steep rear end gears are not the be all and end all to going fast. It should match your engine combo and what your goals and uses are for the car.

 

ok. the th350 tranny is a newer th350. with a 4 speed automatic i think. idk for sure. but i want to accelerate fast. and i know the 3.73 or 4.11 gears are going to do that for me. add on a smallblock 350 then the gears and it should be good. gas not so much but w/e. noow

how do i know the th350 is going to bolt right up with no problems. will it?

 

There's no such thing as a "newer style" TH350 with 4 speeds. Those are called :drumroll: The TH700R4!!!! Which is exactly what you have now.
So yes, swap in a working version of your TH700R4 and have fun.

If it's still a 3 speed TH350 (a real TH350), then i'd have to agree with 87ILEIROC, it'll take off slower and you'll get worse mileage. Lose-lose to me. Plus you'd need a different driveshaft, you have to get a torque arm that mounts to the tranny x-member, I think you'd need a new tranny cross member as well. I can't see the benefit unless it's a race only car which needs the additional strength of a TH350, and you WILL be putting in >3.73 right away.

 

ya i have done a ton of research now. and i think im just going to get a rebuild 700r4 and bolt that right up. and i will probably put in 4.11's

 

If you are going to spend the money to rebuild your old unit, google the Raptor 700R4. I had one in my stroked 496 big block mud racer and it is the only auto that held up.

 

I raced my 85 TA with a 700r4. When I bought the car the tranny was bad so the first thing I did was had the 700 built to handle the 406. the on low octane pump gas at LACR not corrected times (5,000-6,000 ft of air) the car ran 13.30's. I traded some parts for 350 tranny and the thing ran like it was pissed off. I posted a 12.74 all things being equal. The mph was much higher (can not remember the diff) This was on old hard street tires with 2 second 60's because I could not floor it off the line it would just blow the tires off. I always rolled onto the gas pedal with both trans. People thought I had NOS because they could hear the car get loader. The most fun I ever had in a car. Drove me and my kids to the track made 6-12 passes and drove home, won many trophies that way. Now I'll make it my driver to Van Nuys and back....it deserves to be a cruise now..Cheers

 

Wow having asked the exact same question almost word for word over a YEAR ago I can tell you that Dana from ProBuilt is right on the money, all the rest of this is theoretical garbage talk. I've done the swap personally; I went from the junk grenade every season 700r4's to a TH350 with a 3000rpm converter. The car has 3.27 gears just like it always has. The TH350 is faster due to the stall but there is virtually NO difference in my times, I gained maybe 1 or 2 tenths from the trans alone. Driving down the highway at 60mph runs 2500rmp vs the old 1700 so I notice the difference but it's live able. The TH350 is built brick tough and hammers the shifts, plus it cost me about 800 bucks less to go this route than to build a proper 700r4 and get a proper converter for it. If you don't daily drive your car put the TH350 in with a nice high stall converter and have fun; if you drive it alot just spend the cash and build yourself a decent 700r4.

 

Most of the difference in power to the ground when 700 vs 350 is the 700 takes more power to turn. that is why when all thing are equal, the manuals are faster, then powerglide, then 350 then, 400 then 700. they all have pro's and con's. If only looking at 1320 ft time slips well the 350 will beat the 700 everytime, I know. The 700 is weaker and more moving parts, that also means more weight. Each tranny wiil fit a need, what are your needs?

 

I shredded one of their transmissions with my mild 383 only running high 12s go for performabuilt they are treating me right!

 

thanks for the question I have the same problem!