bbk 58mm TB installation question

[truckins10]

For those who have installed a 58mm TB from BBK.... Is it common that the two bottom bolts for the TB dont fit the BBK TB and have to be grinded?? Also After I installed the TB, The truck screams to 2500RPM and doesnt back done to normal idle?? How do you get the IAC to reset to bring the RPMs back to normal?? Thanks for your help guy in advanced. Fern Sy#477

 

[SyTyJedi]

Not sure on the TB questions since I haven't installed one of those.

For the idle - check all your vac connections, something has to be seriously loose. Also, readjust the TV cable in case the new TB may throw settings off just a bit. Did you notice anything else fitting differently? Such as TPS, etc?

If it's not fitting correctly and sealing properly that could cause some idle problems as well.

Did it come with a new gasket? What part needs to be grinded exactly?

 

[truckins10]

It came with new IAC and new TPS already installed. Tried switching my old IAC but no differance.It also came with all new gaskets. The 2 lower TB bolt holes were not machined wide enough to accept the head of the bolt. So I grinded the bolt head smaller and widen the bolt opening a bit, I was thinkin maybe the lower to bolts are grabbin and not tightning the TB?? But I thought a more likely cause would be because the IAC needed to be reset?? Any ideas.???

 

[Pittman]

Take the throttle body off and check the gasket to make sure that it has even compression all the way around.

start it with the intercooler off and Just throttle body exposed and slide your hand over the throttle body. It will try to run if the leak is big enough but you will hear a sucking sound, a loud one. That would be your leak. Something as small as the dia of a pencil is good enough to keep it running and like I said will be exceptionaly loud.

I would suspect there is something thats not fitting quite right on the back side of the throttle body.

 

[jwaller]

you now have more surface area with the TB so your going to need to close the TB blades(by using the idle adjustament screw) to help the IAC adjust the idle. if you have a scan tool you need to adjust the idle until you have around 30 counts on the IAC. and yes with my BBK the Stock bolts wouldnt fit in the bottom so I had to machine out some more area so that the lower 2 bolts would go all the way down.

 

[Pittman]

John, is there a need to increase the size of the holes on the upper manifold as well? The round holes located directly aft of the throttle body.

 

[jwaller]

for the 58 yes I think the holes on the manifold have to be opened up. 52 is a perfect fit but the 58 requires some dremel work.

 

[Pittman]

There has been long debate whether this is really worth it or not. What do you think on a pretty heavy moded truck or just my little truck??

 

[truckins10]

Thanks to all who responded to my question. The idle screw just needed to be backed off. Works good now.

 

[FLSY2730]

How do you like the big throttle body? Did you drive the truck yet, any difference?

 

[jwaller]

I have the 52 on mine and I cant really say weather it helped or not. mine is so modified, I would need to swap them now that its running right to really know if it helped or not. but I'm not goin through that trouble. so...oh well. :vamp:

 

[truckins10]

I noticed a big improvement in throttle response. Compared to stock, just touching the throttle really makes the truck go. The reson I changed it was because the throttle shaft was leakin bad under boost, I would get boost fluctuation big time at WOT. Not no more. Fern Sy#477

 

[FLSY2730]

Did you open up the intake holes behind the throttle body to match the opening of the larger throttle body?

 

[truckins10]

No thats the strange thing :-? I dont know if maybe my old TB was causing that much problems that the new one cured??