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#1
02-02-2009, 04:29 PM
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TH350 or TH400
With my new 383 build, I am not sure what trans I should use. I have the stock TH350 that came with the car which worked fine prior to teardown. I had planned on rebuilding it and doing some minor upgrades listed below.
I also have a TH400 from a 77 Caddy. It came with my 71 and I had planned on keeping it with that car since I will eventually be running a built 400 engine in it. So essentially I have everything I need, including driveshaft, with my 71 if I wanted to move it over to the 72. I prefer to keep the original drivetrain with the 72 so if the TH350 would hold up behind a decently built 383, I'd like to do that. However, if the additional torque of the 383 will tear up the TH350, then I'll have to move the TH400 over from the 71. I have Ron Session's books for both the TH350 and TH400. I've read them both and planned on accomplishing a couple of his high-peformance longevity mods. Namely a shift kit, hardened intermediate roller-clutch outer race, and wider direct-clutch-drum bushing. I want to keep it from being too harsh on the street but yet hold up behind 400lb/ft of torque. Adding a bit more fuel to the fire, right now the car still has it's stock 2.73 rear and I had planned on using a stock or near stock converter. I know this will cause additional stress on the trans (namely the 2.73).
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John Pontiac-less for now |
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#2
02-02-2009, 06:55 PM
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An upgraded TH350 will live behind 400ft/lbs. I'm not familiar with the Pontiac 383 stroker, but I would assume that it would run like a hot street 389 or 400. Just build the TH350 with good parts, all new bushings and bearings and a trans-go kit. 5 clutches in low, 5 in direct, 5 in FWD, 3 in intermediate. Orange spring in 1-2 accumulator. Keep endplay to .005" to .020". Tight is good!
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I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 |
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#3
02-02-2009, 07:08 PM
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The TH350 will be fine, i have been running one for years and no complaints yet!
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Derek B. Current best: 11.97@110 1.65-60' !!! '74 ventura,  (Fired july 14/06) '74 462 4-bolt (9.5-1), SCAT, Ross, T-II w/850DP (shaker455), TH350, Conti 10'' 3800, Supercomps, Magnaflow, 3'' Pypes, 3.73's, 28x13.5-15 ET streets.1970 Beismeyer 17' flatbottom vdrive, 11.8:1 455P, ported heads, dual Qjet tunnel ram. 
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#4
02-02-2009, 07:08 PM
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Use the Turbo 350 it has a lower 1st gear [2.52 vs 2.48] and uses less horsepower than a turbo 400.I'm putting a turbo 350 behind my 455.
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#5
02-03-2009, 10:00 AM
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Stick with the TH350, correctly prepared they are fine for what you are doing. We have them in 10 second cars clear up to 750hp, no issues anyplace.....Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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