how many of you guys have converted from a 350 to a 455? and how many of you still use your th-350? i have the 350/350 combo in my lark right now but when i finally get that big block in there will i have to spring for a new trans. at the same time?o No: im hoping the engine will have around 450 hp/450 tourqe. eventually will want to do the upgrade but of course it means more money up front, and more time till i can drive it again. and that would suck! so i guess my question is, can a solid built th-350 handle the 455 for a while? pete
Pete, A TH350 "can" built to handle 450HP, yes, but you might be better off using a TH400, or even a TH200/4R (overdrive). Personally, the TH350 or the TH200/4R are my choices, as they're "easier" to work with, and more available from junk yards, to rebuild. Also, the TH350 and TH200/4R are very similar to each other in length, etc., and make a swap a little easier, too.:Smarty: Cost to rebuild any of these 3 transmissions is going to be about the same, for the kind of "Heavy Duty" rebuild that you want. I'll estimate $800-$1200, and I should be pretty close!:Smarty::TU: Things to consider, anyway...:bglasses:
Pete, The 350 will handle a 455, depending on what you do with the car on the street. If you build it right, it will last, but if you race the car and hook it up solid, it might not last as long as a 400. I wouldn't be doing any hole shots with sticky tires until I knew I could afford a 400.
yeah i here ya. i dont plan to beat on the car too much. especially on the street. street racing is just too much of a risk here in cali, and i dont see myself getting to the track any time soon. i just want the engine in there first cause thats what i have to start with. then ill have to work my way to the back of the car. the transmission i have was built a couple years ago and i was told it came out of a 455 car. its very solid connected to my 350 right now. so i think itll hold up for a while unless i do something really stupid. heres a dumb theory i have though. feel free to shoot it down if im wrong... would a th-350 rob less power then say a th-400? reason being, smaller/lighter parts?
yes and yes yes a t350 will hold up to the 455 output and yes it does have lighter parts andless resistance to turning. my car has had the original t350 behind a 455 since 1987. has had one complete rebuild when i put the 455 in, and one freshening in 1994, which was a couple of seals, a low gear planet set (which had become noisy and was the reason for the tear down) and it has been used with a 3k stall 10 inch converter for over 30k miles and currently wears an 11 inch 1800 stall unit. use behind the 455 totals over 50k in mileage and over 150 drag strip passes with no ugly incident. i would also point out most nhra automatic racers are opting for built 350's or 200's with lightweight geartrains in stock eliminator. you can sometimes find them for sale at classracer.com or superstock forums.com
Personally run the t-350 behind my stroker. The sprag assembly is a big problem ( trust me, I granaided one ) It is lighter because of the lighter duty parts but will take a LOT to make it happen. Check under search on this board for turbo 350. B&M and TCI make the part.
