I just put together a 3.4 conversion with a 4t60 transmission in an 88 fiero. The transmission was just rebuilt buy a reputable shop. My issue is when I proceed forward from a dead stop the RPM's seem to get to high to get the car rolling. The convertor installed is a Precision 4847FDHB which is a 2095 stall. Is this to high and what would be the suggested stall speed convertor? Any suggestions would be greatly appreciated.

"Stall Speeds" is a popular # and a myth. Used by aftermarket to sell TC to the pubic. GM may publish a "stall speed" because public wants this but isn't really used by GM and most others.

Beyond that...
Your problem may not be the TC at all or maybe only partly and have wrong gearing or setup for the "dumb" 4T60 for the engine and car.
4T60 needs correct settings for TV cable, Vac Mod, and the Governor that drives VSS to even hope the trans shift right and doesn't cause big problems.
You need tools and pressure gauge(s) to setup TV cables w/ most engine swaps or will cause low/high pressure in the trans. Same for many Vac Mod.

Your best bet is go to the Trans rebuilder or another trans shop and make sure you install and setup those two parts and minimum. Trans shop can respring etc the governor if needed at same time.

4Txx often come out of heavier vehicle and need changes to the governor. Most Rebuilder won't changes this w/o more data, even then may need to change after install.

Vac Mod Need Full Manifold Vacuum. Not Ported Vacuum many ports on TB/TBI are.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

So the 3.4 engine and the 4T60 were already in the car and i've had it for several years. Since the motor was tired I decided to purchase a remanufactured long block and took advantage of having the transmission gone thru because of the work involved to remove and install the cradle. Before the tranny was rebuilt of which there was really nothing wrong it took off quicker from a dead stop which is why I was questioning what stall speed convertor shoud be used?

I would confirm fluid level. You’re checking with the engine running and transmission warmed up, correct?


“2095” sounds right for a stock v6 fiero stall rating. As Ogre stated, there are several factors at work for actual stall, but I think your problem lies elsewhere.

[This message has been edited by Honest Don (edited 01-06-2021).]

quote Originally posted by JeffreyMiller: So the 3.4 engine and the 4T60 were already in the car and i've had it for several years. Since the motor was tired I decided to purchase a remanufactured long block and took advantage of having the transmission gone thru because of the work involved to remove and install the cradle. Before the tranny was rebuilt of which there was really nothing wrong it took off quicker from a dead stop which is why I was questioning what stall speed convertor shoud be used?

Just because trans works before doesn't mean TV cable etc are right now.

For that matter rebuild engine could have problems too.