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Old 07-10-2004, 10:25 PM
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700r4 Swap to a Turbo 350

OK i have a 1984 chevy camera with a 700r4 transmission in it but I want to put a turbo 350 transmission in it I got all the parts to do the swap but I was looking at the turbo 350 transmission and it has a vacuum line on it and the 700r4 does not so how do I make a vacuum line for the turbo 350 or can I just cap it off?

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Old 07-11-2004, 03:45 AM
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Ummm.. I have to ask.... Why?

I could understand if the 700 was dead, or dying, but you do realize that with the THM350 you will not only cut your take off speed down, but you will also kill your top end speed and gas mileage.

Seriously I would like to know why.
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Old 07-11-2004, 12:07 PM
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its not mine it is one of my friends and i am only puting it in for him because he does not know how to so i told hi i would help him do it i do know the turbo 3550 has a shif kit in it
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Old 07-11-2004, 02:27 PM
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this is the same thing im doin in my s-10 but the reason im doing it is because i keep blowing 700s up and they never seem to work properly so now i got a rebuilt th350 that i knwo will work good -sure ill lose some milage but i highly doubt my out of the whole performance will change because this one has a stall and the other one had nothing but a stock 1600 rpm stall -but as for the vacum line just goto the local parts store buy some small diamater steel tubing(looks like brake line) bend it to fit down into your trans then attach one end to a manifold vacum source(should be at least 12 inches at idle) and the other into the transmission use small pieces of vacum rubber line to attach the steel line
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Old 07-11-2004, 08:16 PM
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As tire said, just run the line from the trans up to (usually) the back of the manifold. Or if you have to you can by a vacuum spilter from advance and run it to the trans from a vacuum line thats already there.
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Old 07-11-2004, 09:53 PM
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what will happen if i dont hook it up?? or just cap it?
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Old 07-12-2004, 05:53 AM
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As far as I know, you might have problems shifting out of park with it disconnected. BUT other people claim to have removed the vacuum line on the TH350 and have had no problems.
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Old 07-12-2004, 08:49 PM
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If you don't hook up the vacuum modulator line on a th350 you will have late and harsh shifts.....hook it up
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Old 07-13-2004, 12:33 AM
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The tranny also wont shift back down until you come to a complete stop. At least this was the case of mine. The 700 is a far superiour tranny in my opinion granted its hooker up right (Tv CABLE). Try and talk your friend out of it. Like was said . . . get a modulator and hook it up to a vaccum port and you'll be set.
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Old 07-13-2004, 09:14 AM
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I am putting a 700 in my 48 Chevy P/U after ruling out the th350. I don't have words of wisdom here but I do have a question along the same lines....sort of. The rearend I have to put in the truck is out of a 79 Nova and has 2.73 gears. Wanting to spend more of my money right just getting the truck on the road I am hoping these gears aren't to high. The lower first gear in the 700 should help with take off, but is the final going to be too high?
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Old 07-13-2004, 02:44 PM
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If your asking if the 2.73 rear end is too high for the 700, than the answer is no. The theoretical top speed would be over 200MPH. If you meant 3.73's than still no, your top speed would be like around 160 (which would be interesting to see a truck get that high )

If you mean a 2.73 rear end on a TH350 then your top speed would be around 150MPH, 3.73 would'nt be very usable with a 350 because it would limit you to a top speed of around 120 and thats pushing near 6000RPMs on 26" tires.

All calculated numbers though, up to you.
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Old 07-13-2004, 02:53 PM
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Thanks for the reply.... I guess I was a little nervous about the 700R4/2.73 combo and how streetable it would be. I would have loved to find a posi unit to put in it but this rearend was inexpensive (cheap) and available. I have looked at ordering new gears for the rearend, what do you all think would be a good number. 355ci, 4bbl, headers, 700r4. Thanks again.
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Old 07-13-2004, 09:30 PM
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My 84 blazer has 2.73's in it and before I hotrodded the engine it would never stay in od. After cam and heads it would stay in and now it gets around 17 mpg. When you get the 700 in make sure you have the lockup working and set the tv cable up right or you will cook the trans.

John
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Old 07-16-2004, 12:45 PM
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th350 is a lot better than a 700r4
parts are cheaper and stronger and there is more stuff you can do to them.
700r4s are weak and unreliable. but they work good for awhile as long as you dont have a lot of power.
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Old 07-16-2004, 06:52 PM
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Quote:
Originally posted by blazinwest
th350 is a lot better than a 700r4
parts are cheaper and stronger and there is more stuff you can do to them.
700r4s are weak and unreliable. but they work good for awhile as long as you dont have a lot of power.
Weak and unreliable?? I couldn't disagree more. 700 can be build every bit as strong as a 350 how ever its true that a 700r4 will cost more to build.
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