bigscaht Posted September 7, 2006 Share Posted September 7, 2006 Hey guys heres a question for yall! I have a 72 monte with a th350 which has been rebuilt about 5 months ago but only has been driven about 15 miles since the rebuild due to the fact that the engine is gettin ready to go. A friend has a great running 454 eh wants to sell me and I was wondering first of all would the 454 bolt up to the th350 and if so what other changes besides motor mounts would I have to make to complete this swap? Quote Link to comment Share on other sites More sharing options...
680HPStroker Posted September 7, 2006 Share Posted September 7, 2006 I'm not 100% positive, but I think it will bolt right up. If the 454 you are looking at is a mild one the turbo 350 will hold up for a while, but if the big block has any measurable performance work done to it, or go fast goodies on it the life of the turbo 350 will be short lived. If you are set on having the turbo 350 you might seriously want to think about either going back through it yourself, or have a reliable shop go through it and update it to withstand your current power level and any other mods you may make in the future. Personally I'd drop in a stock turbo 400 and call it a day. In stock trim a turbo 400 is capable of withstanding 800hp. If you are possibly looking at an overdrive you could either put a gear vendors unit on the back of the turbo, or opt for a GM 480LE tranny. The 480LE is heavy and will require a separate control module for automatic shifts, but it like the turbo 400 is almost bullet proof in stock trim. I have a GM 700R4 that I had to put over $1000.00 in high strength parts in order to even think about beating on it with over 600hp. In the end it's all in what you want, how deep your pocketbook is, and how often do you want to be going back through and rebuilding something. Just my two cents. Quote Link to comment Share on other sites More sharing options...
Heckeng Posted September 7, 2006 Share Posted September 7, 2006 You bet, a th350 will bolt right up to the 454. I have had a 454/350 combo in my car for 8-9 years now. I've changed transmissions or had them rebuilt 3 times in that 9 years just because I figured that they would be weak, and I wanted to find any problems in the transmission before it left me stranded. I have NEVER found anything wrong with them when I took them out to rebuild. I have always used B&M full rebuild kits with red alto and kolene clutches and steels, and everything has worked out great. I have only put one hardened part in them because my friend who rebilds all of them for me said that this part always fails. It is the intermediate outer race. You can get them through Summit for around 40-50 bucks. The stock races usually don't take too much abuse/torque and they'll crack--at least that is what I've been told. Â I have run 12.75 at the track on slicks, and have done more stuff since then hoping for low 12s and the transmissions have done great. I believe my engine is putting out around 475hp, and 550 lbft. Nobody has any faith in the th350, but I think it's the "lil tranny that could"! Â The same guy who builds my transmissions, races a mostly steel (fiberglass hood) 68 camaro with a 468 that runs mid 10s and he still uses th350s too. Â How much torque/power do you think this 454 is putting out? Quote Link to comment Share on other sites More sharing options...
Guest Posted September 7, 2006 Share Posted September 7, 2006 T.H. 350's trans are way underated.... I have at least 400 legal passes with the orginal 72 350 trans. the only thing I did to it was put at B&M shift improver kit in it way back in 94 and it still works just fine and I run high 12's / low 13's with a mild 355 small block.....so go for it bigscaht, you should be fine. Â Quote Link to comment Share on other sites More sharing options...
KLASSIK1 Posted September 7, 2006 Share Posted September 7, 2006 when i was young i used to get rollin about 30 in reverse and drop it into drive good clean fun only grenaded 1 350 turbo but it was actually the tailshaft that came off , the 350 is a bolt in replacement for the powerglide commonly used in the 60's , what about a 375 turbo most never even heard of it but it did exist  Leo Quote Link to comment Share on other sites More sharing options...
dmdbit Posted September 7, 2006 Share Posted September 7, 2006 Over a year ago I put a too mild 468 in my car in place of a 350.I rebuilt the t350 at the time with a shift and used it.I put new motor mounts on the block for a 454 and it dropped right on the small block mounts.Other than accessory brackets on the motor it is truly a bolt in and go.Crossmember location is the same meaning the driveshaft is reused as well. Â mike b Quote Link to comment Share on other sites More sharing options...
bigscaht Posted September 8, 2006 Author Share Posted September 8, 2006 thanks guys for gettin back to me...you all have made my decision a lil bit eaiser..so my next question is should I go with a higher stall converter or stay stock? Quote Link to comment Share on other sites More sharing options...
dmdbit Posted September 8, 2006 Share Posted September 8, 2006 I would have to say yes,I wish I had.Reply with the cam specs and rear axle ratio and you will receive some good opinions you can choose from. Â Â mike b Quote Link to comment Share on other sites More sharing options...
680HPStroker Posted September 8, 2006 Share Posted September 8, 2006 In my previous post I was just trying to be cautious. As the old saying goes you can pay now, or pay later. I like to do things right one time and be done with it. I know that a budget can be a deciding factor in all this, but a little extra money for years of piece of mind to me is worth it. I used to be fixed on one thing and thought that it has never let me down and never will and then all of a sudden there it is, a failure! You are free to do what you want and listen to whoever, but for my money spending it up front for max reassurance is the best way to go. Quote Link to comment Share on other sites More sharing options...
KLASSIK1 Posted September 8, 2006 Share Posted September 8, 2006 Greg is right , a 350 will last years BUT gm did build the 400 for a reason it was a HEAVY DUTY trans and i do run them behind my big blocks that is my preferance , but the 350 is not a junk trans and neither is the powerglide , most trans failures i have had have been due to poor rebuild workmanship or lack of maintenance  Leo Quote Link to comment Share on other sites More sharing options...
Guest Posted September 8, 2006 Share Posted September 8, 2006 DITTO LEO..../ I truely believe the shift improver kit was the key to the long life of my 72 350 trans. Â Quote Link to comment Share on other sites More sharing options...
John Burns Posted September 8, 2006 Share Posted September 8, 2006 My stock th350 with a B&M shift kit does a fine job behind my 454. I've gone 12.4 @ 111 and I punish the car regularly and the trans doesn't care. Yeah, cam and gear specs needed for a converter recommendation. I'm happy with my B&M "nitrous" 2400 converter with 3:31 gears and an "LS-6" cam. Quote Link to comment Share on other sites More sharing options...
bigscaht Posted September 9, 2006 Author Share Posted September 9, 2006 cam specs on the 454...im not sure of but it idle regular so the cam cant be to far from stock. it has and edlebrock rpm intake and i have brand new 600 cfm edlebrock carb and the stock q-jet on the 454 which I might jus leave on there. As for my rear end....right now its the stock one tire fire with those good old 2.73's out back. not sure when ill be upgrading that old thing! mabye around tax time next year!!!! Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted September 9, 2006 Share Posted September 9, 2006 I destroyed a well built TH400 in my Monte as well as the 9 inch rear. If you're producing power with any size engine, and you hook good with these heavy cars, you'll surely break a TH350. I had a TH350 behind a very mild 350 engine in a '73 Impala and it broke twice. Â There may come a day when we can buy and install the new 6L80/6L90 in our cars. Imagine a super duty six speed auto! Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 9, 2006 Share Posted September 9, 2006 a properly built 350 will do just fine behind a mildly built 454, if it breaks, it would more than likely be from abuse Quote Link to comment Share on other sites More sharing options...
Heckeng Posted September 9, 2006 Share Posted September 9, 2006 Parts and general availability are also much better with the th350. You can still find them in salvage yards around here, but you can NOT get a th400. You have to know somebody with one, and then weasel them out of it! It would be nice if the 400s were cheap and plintiful and also strong, but I think they are only one out of three! Quote Link to comment Share on other sites More sharing options...
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