Not talking about what the TPS reads, talking about the physical throttle body. I took my car to the shop about the fact that after installation of a 52mm TB, when pedal is pressed to the floor, throttle only opens about 80%. They said that it's fine, that's good enough. I said I disagree and asked if this was an 8 second bracket racing dragster if they'd tell them the same thing? They said yes.

What do you think? 80% throttle open good enough? Pretty sure answer to this is no but validation always feels good

 

On the face of it no. 80% is not WOT. But of course the engine has to be able to handle the full open throttle. Maybe(?) that's what the shop means but I'd be suspicious. Some of the first gen Firebirds had the throttle restricted from opening fully because the GTO was designated as Pontiac's fastest model. But was just a small metal tang that could be bent back to restore full throttle.

 

For a DD street car you'd probably see very little WOT, unless you drive like me. For any type of performance it should be opening 100%. Thats even what Carb install directions put down multiple times. Yours is a T56, but if it was a 700-R4 it would not pull on the kickdown cable as much and would affect line pressure too, until it was readjusted. Next step would be to find out if it's binding up. I never moved from the stock TB on my TPI so I can't really point you in the right direction.

 

I agree with you. It is common for our cars to have issues getting to 100% open on the TB. Make sure that the floor mat isn't under the go-pedal. And sometimes need to pull the carpet back and remove padding from the area under the go-pedal.

I had to do both on my stock '92 to get a fully open TB.

RBob.

 

The cables do fray and can stretch. Be sure this isn't the case. You can also slot the mounting holes slightly in order to adjust the cable's effect on the throttle linkage. Be sure to reset the TV cable afterward.