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One of those "do ya think it will hold up" questions

Discussion in 'The Garage' started by Robert79K5, Nov 15, 2005.

  1. Robert79K5

    Robert79K5 1/2 ton status

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    I typically shy away from asking these types of questions but....

    How well do you think a TH350 would hold up behind a stock cadillac 500 engine in a light weight (k5 frame, s10 body, no bed, 36" tires) trail only truck?

    I know I know.. just get a 400 and be done with it, but I have two freshly rebuilt TH350 spares laying around. I just don't want to be swapping them in after every trail run.

    Im thinking it will hold up pretty good under my light weight trail truck.

    The kind of wheeling Ill be doing with it is muddy hills/trails, some slippery wet rocks and mud in general.
     
  2. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    sell the two fresh th350s and buy a 400. :grin:

    j
     
  3. Paxx

    Paxx 1/2 ton status

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    I think it will last a little while anyways but will break eventually. I have a stock 500 in my 81 with a th400 and the 400 is almost toast. It sees lots of burnouts on dry pavement with really bald tires which might be the equivalent of muddy rocks :deal: and my pickup is probably no heavier than your trail truck if not lighter. It's 2wd with no weight over the drive tires.

    I honestly think you would be better off selling the th350 or trading for a th400. I would hate to see you have to rip it all back apart after toasting the 350. Even stock those 500's have too much torque for a lesser tranny.

    I know its not what you wanted to hear but I hope this helps
    ~Max
     
  4. sweetk30

    sweetk30 professional hooker Premium Member

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    i have had a built 400 sbc with 350 all of it was in over 6500lbs total with 38s . still going after 5 years . was built with good parts and shift kit. friend has 454 with 350 in 5500 lbs truck with 35s still going fine. both trannys had allison hd towing convertors . with trans star reman kits and no yo yo shift kits .


    keep it cool and go for it. also if you go 400 you will loose better first and second ratio and eat 20-25 more hp in the 400 as its bigger inside.
     
    Last edited: Nov 15, 2005
  5. trailblazr81

    trailblazr81 1/2 ton status

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    Buy a good torque converter and get the biggest cooler they make and it should be OK. Are the TH350's old? Rebuilt? stock oem rebuild or rebuilt with better stronger stuff?
     
  6. Robert79K5

    Robert79K5 1/2 ton status

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    Thats not a bad idea but im not really having any luck selling them for less than what I think they are worth.

    If I go with the TH350 I can just drop the engine in there and go since it alredy has the th350 in it hooked to the SBC. Ill just need to get the chevy to Cadillac adapter. I like that as it will speed up the process of me getting this project going.

    The two spares were rebuilt by a local reputable shop. One has a shift kit and the other has stiffer springs to make it shift firm but not change the shift points.


    Im not complaining here. Its fun to have to worry about having too much engine for your driveline. :D
     
  7. diesel4me

    diesel4me 1 ton status Premium Member

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    I'd run them...

    I've had TH350's behing the 454 in my Chevelle wagon that was on the 69 Burb chassis,and my 74 K20 had one behind its 454 and the 400 SB I installed--beat it for 15 years plowing and hauling heavy loads..only thing optional on both was a decent sized cooler,heck,I only changed the fluid and filter once on both,and they looked nice and clean inside..

    The one in my 74 K20 finally lost reverse last winter,and it was so rotted I decided to cut it up for scrap..the one in my wagon eventually slipped as it shifted into 3rd,but that was after 25,000 miles,and I beat the thing pretty hard on the street..it ran hot too,I think that helped wound it too--but it never failed me..

    I would just use what you have,since they are free,an adapter plate only costs 70 bucks at Jegs..The caddy motor does have enough torque to kill the TH350 if you abuse the hell out of it..but if you drive it sanely,and it has low enough gears in a light vehicle,I'm willing to bet it might suprise you how long it will last you..beat the crap out of it and do 4wd burnouts,it might last a few hours too..since you can't sell them for decent money,and you have 2,why not use them?...I would.. :crazy:

    I met another guy with a caddy powered GM 4x4 the other day..didn't see his truck,he was picking up his wifes car at my friends shop,and when he saw my K20 he told me he had a similar one with a caddy 500 in it! :laugh: ..he said he used a Pontiac car TH400"short tail" tranny from a firebird,and took the tailshaft housing off,and mated it to his original NP208 that had a TH400 input--.
    (the original chevy TH400 was missing when he bought the truck(someone had bought the truck just for the 454 and tranny,he bought it after that)..

    He said he made a home brew "tailhousing to transfer case adapter" out of a peice of pipe and 2 peices of 3/8 thick plate --he traced the bolt patterns off the original NP208's adapter,and drilled the holes and hole sawed the center out to let the shaft go thru..made the pipe the proper length so the right amount of splines stick out to go into the transfer case.,and welded the plates to the pipe,and bolted everything up !--

    It takes the place of his original adapter..he said it works fine!..he didn't go into a great detail of everything he had to do,but said he will probably bring the truck to my friends shop soon--I'm hoping to see how he did this,it sounds interesting.. I'm thinking the transfer case had to be moved on the frame slightly,since car VS 4wd TH400 output shafts are different lengths .. :confused: :thinking: :dunno:

    I saw a 2wd GM truck with a 500 hacked into it too,at a car show last summer. It used the OEM caddy super long tailshaft TH400--it had a rear driveshaft about 2' long!..the motor mounts were hacked bad,the motor was way high and tilted back--but the guy claimed it drove good,no excessive vibrations..I think he lied.. :haha: :rolleyes: he did an awesome burnout with it though! :bow: :crazy:
     

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