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jeff l

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I have a rebuild motor that should make almost 400hp with a rebuilt 700r4. I feel like the power is not getting to the wheels. I took it to a mechanic and he said he thinks its the trans, he would not have put that trans with a moter like that. he would put a t-350 or a powerglide. I am thinking i would rather a standard.
what is your opinion? and is very hard to convert auto to stanard?


3.73 gears
 
I am running a 700R4 behind a 350 putting out 350hp/400lb.ft and do not have any problems. a 350 trans or powerglide are not really any stronger. a 400 would be better. is it slipping? how long ago was the rebuild? what makes you feel its not getting to the ground?
 
Definately swap to the SM465, you will never want another auto ever again!!! :D
 
the 700 would not really be any different from a 350, the 700 is based off a 350 tranny. and besides the 700 has a better first gear ratio and has over drive and lock up clutch.
 
are you sure its a 400 horse SBC? was it dyno'd?


are you maybe expecting something that was never really there?


is it set up right? carb? timing?

If something got messed you can turn a good engine into a dog in a hurry
 
A 700R4 is fine. I'm running a 400+ HP 383 in front of a stock 700R4 and it'll plant your ass. If you're concerned about the transmission, there are plenty of upgrades available for the 700R4 now.
 
gmc4cw said:
I am running a 700R4 behind a 350 putting out 350hp/400lb.ft and do not have any problems. a 350 trans or powerglide are not really any stronger. a 400 would be better. is it slipping? how long ago was the rebuild? what makes you feel its not getting to the ground?
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the trans was rebuilt the same time.
its not slipping
I just spent 10 k on rebuilding this truck ,and i would think 375 hp should spin the tires.
 
jeff l said:
the trans was rebuilt the same time.
its not slipping
I just spent 10 k on rebuilding this truck ,and i would think 375 hp should spin the tires.
Click to expand...

What size tires? If your running 35's with 3.73's and a locker you may not spin 'em. And like mentioned before make sure the motor is tuned right. Also a bit off topic if you dont already have one go out and get the biggest tranny cooler you can fit!!
 
1979jimmy350 said:
the 700 would not really be any different from a 350, the 700 is based off a 350 tranny. and besides the 700 has a better first gear ratio and has over drive and lock up clutch.
Click to expand...
I really wish i new more about all the trans, so bear w/ me. my 700 was paired w/ a 305. no offense to people w/ a 305 but it was a fuel and a smog conscience set up. the ratio is different, or should i say perfect ratio to a 305. I now through in a high hp motor. I just wonder is it working all in sync

I am not saying the 700 is 100% to blame, i just thought this was something to think about.

also i forgot to say the 700 rebuild has a shift kit and i had to put a different type lock up for my converter. b/c the computer does not control it
 
trailblazr81 said:
What size tires? If your running 35's with 3.73's and a locker you may not spin 'em. And like mentioned before make sure the motor is tuned right. Also a bit off topic if you dont already have one go out and get the biggest tranny cooler you can fit!!
Click to expand...
30' tires
3.73
eaton posi
 
you should be able to roast those tires. at the very least it should bite and launch and snap your neck back. I am running 44's with 4.56/detroit and can spin the tires at will. TORQUE BABY! :bow: I can put the bumper against a wall and spin all 4 if I want. when I had boggers it wouldn't spin on dry pavement, way to much traction. what stall is your converter?
 
gmc4cw said:
you should be able to roast those tires. at the very least it should bite and launch and snap your neck back. I am running 44's with 4.56/detroit and can spin the tires at will. TORQUE BABY! :bow: I can put the bumper against a wall and spin all 4 if I want. when I had boggers it wouldn't spin on dry pavement, way to much traction.
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your gearing is also different , I have 3.73
 
What are the specs on the motor? Compression, cam timing, heads, intake, exhaust? Did you copy someone else's build that was dyno'ed at 375-400 hp, or are you just guessing?
 
If the thing has a carb I'd bet 100 percent it's not tuned right... carbs are very tricky without experience or good equipment. I couldn't count how many dyno runs I've seen where the right tune will give you another 40 hp... timing has a lot to do with it too.

GM4CW: What are the specs on your motor? I'm guessing bb? spinning 44's with 4.56 gears is impressive... unless your using granny gear:D
 
I don't have the specs in front of me. It puts out over 400 lb-ft of torque pretty much off idle to 4000 rpm. makes around 350 horse around 5200 rpm. redlines around 7000. It's a 350 4 bolt main originally out of a 91 vette (center bolt valve covers) then rebuilt with a wild cam. It lopes nicely.:D getting the carb and timing set right is everything. Dyno time is worth every penny. you get real numbers and can see what changes do what. I have a 700R4 so not really a granny(3.06:1) I just mash it and let it do its thing.

Best part is I went to the guy with a set of heads, rear main seal and tins. He built it for $1600. that included the dyno runs. That was 6-7 years ago. He just sold his speed shop september 1st.:mad:
 
jeff l said:
sorry if i sound dumb but what is SM465
Click to expand...

The SM465 only the beefiest tranny ever available in GM trucks. It is not an auto, it is a stick and is amazing. Do a search on SM465 swaps, there is alot of info out there on it.
 
An Allison will eat a 465 for lunch. A 465 is not for everyone though.

and...he's not a paying member, so no searching....except for google...
 
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