Replaced TBI with Carburator, 4L80E wont shift

yeah this will work....most 350 big blocks come with either a 350, 350 turbo or 400 turbo transmissions.....bolt pattern is the same

ECM is ELECTRONIC CONTROL UNIT

there is a transmission sensor on the top of your motor by the intake. it senses the accelerator or motor rpm's and tells the ****** to shift. its about 30.00 and easy to change. get it at any auto parts store.

for a swap like that a chilton book would cover info for both motors and they cost under 20 bucks. just saying it beats the hell out of guessing at it or taking some schmucks advise from the internet. since your old 5.7 had TBI im hoping the 454 your swapping it with is also a TBI, if not your best bet would probally be to convert to carb but your going to need to replace the fuel system as the 2 high pressure lines that ran the TBI wont work with a carb. if it is TBI your going to need the ECM that came with the 454 as the 350 one is just going to "get confused" and have issues. Since your rig has an older ECM you can remove the Electronic senders and replace them with manual ones to simplify everything ( i have an 89 chevy i built a rat 355 for so ive been through this before) . without knowing exactly the year of the 454 thats about all i can think of to watch out for on that swap, i hope your not trying to mate the 454 to a 4L60, your going to need at least a 4l80 with an upgraded sun shell gear or a heavy duty manual ( at least 10 spline and 12 inch clutch).

the transmission will bolt up fine I think you may need a longer driveshaft as the 4l80 is a longer tranny. measure both transmissions and see for sure other than that should be an easy swap.

Bad transmission, that's not a good answer. Bring it to the shop [so we can guess around], not a good answer either.

A good mecahanic will respond with something about the solenoids.

I have repaired the 4L80E on my tow truck, I have to do that almost every year, the last time it ran perfectly but when I push the pedal to the metal, it shifted from 3rd gear to 2nd and stays on 2nd gear until I turn the ignition off and start again.

The transmission was totally rebuilded so the answer "Time to rebuilt the transmission" is not acceptable.

I took it back to the shop and the mechanic replaced both solenoids A and B, that was the only thing that hasnt been replaced before, it was just a guess but works

So, I am not a mechanic but my sugestion is to replace the two speed sensors and solenoids before you take the tranny out of the car and be carefull who are you taking the transmission to because guessing is not always the best course of action

The two speed sensors are easy to replace, the solenoids are inside of the valve body but you may be able to replace them without removing the transmission from the truck

yes but you may have to change output shafts, costs $85.00

Yes.

should bolt on, but check starter bolts w/flywheel