Hello, my latest car project(its been a long time) is a 91 Camaro RS 305 with TBI/EFI.

I know very little about Throttle bodies so I was hoping someone could shed some light on it

Ive looked on websites like Edelbrock, Holley, and Deamon and can't seem to find a bigger throttle body that will bolt up without any other modifications.

Ive been seing 58mm throttle body sizes here and there, how much bigger would that be than my stock throttle body and would that be to big without a manifold and/or other upgrades.

How can I tell what size mine is?

Will throttle bodies bolt right up to any manifold like an Eldelbrock rpm performance air gap, or is there certain manifolds you have to order for throttle bodies OR is there adapters that will allow throttle bodies to bolt up to standard manifolds?

I plan on putting a whole new crate engine probably a 350 but plan on keeping the EFI/TBI

Thanks in advance for any info/advice.

 

TBI...............

I'm not a fan of it at all. It's not too great for making power, although there are people out there using it.

As far as throttle bodies, keep the stock one and spend your money elsewhere for now. If you do drop a new engine in there, then I can see going with a new throttle body.

 

A stock TBI has been shown effective to about 275-300 HP with good injectors. If you're looking for over that you'll need to move to the GM 454 SS TBI or the Holley 670 cfm (both have 2" ventri). Either can be bolted up to the Edelbrock Performer TBI, if machined to 2" from 1 11/16ths or any 4bbl carb manifold with a Holley adaptor. Im running a Performer RPM with the adaptor (found at PAW for like $12).

****ty parts to replace before the engine: exhaust (standard 3" all the way back), gears, non posi rear, and 1200 stall. Best place to start is with the ultimate tbi mods in the tech articles on www.thirdgen.org. The tbi board there has a ton of info, so do some searches and you'll probably find what you need. If not post 'em up and we'll answer them as best we can.

 

good injectors? I thought only TPI had injectors, or are there injectors in a TBI ?


Edelbrock Performer TBI? is that a specific manifold for TBI? or did you mean a regular Edelbrock Performer?

Thanks!

 

XThree
I think you should do a little more research on the basics of your 305 TBI .

 

Uh yeah. thank you mister obvious. thats what I came here to do. just found out about thirdgen.org so thats helping

 

Your welcome....

 

Your throttle body has two injectors right in the center of the unit. I have a 9C1 Caprice that I have the 083 300hp 350 heads an LT1 cam and 3 inch exhaust that has the factory HO injectors . I am using a stock manifold, but Edelbrock has a TBI manifold. You need an adapter to run a carb manifold with a TBI unit.

 

Picture of my tbi setup

Thats with the Edelbrock Performer RPM intake, Holley carb -> tbi adaptor, and then the stock tbi with some shoddy ultimate tbi mods done to it. Injectors are on top there, with the two wires running into each. Pretty messy picture though, I gotta go get some new ones with stuff fixed on it

 

you shoudl start your tbi research at www.thirdgen.org . there are a series of tech articles listing soem easy free mods as well as a tech board dedicated to tbi.
several people have gotten great gains from tbi, and it is a lot easier than a lot of people think.

later
tim

 

ah i c the adapter, and the injectors.

does edelbrock sell the adaptor or someone else?

Thanks all for the info

 

I would do some headers and gears first. With the mods you have you won't see a gain. If you are doing the heads and cam then go ahead and do the TB and intake. Hope this helps