Just "eyeballing" it, I do believe my Holley 58mm throttle body is centered as compared to the stocker. I can tell you for sure that the AS&M 58mm throttle body is NOT.

With that being said, I believe the AS&M throttle body is of higher quality with less "issues" than the Holley.

 

I would order a t.b first, and when it arrived I wolud line up the gasket on the intake, then scribe the lines, and then port accordingly. Each t.b. seem to line up a little bit differently. A good choice IMO is the ASM 58mm. My Holley 52mm. is ok but I had a problem (many others seem to have probs. with holleys) with thte blades sticking, so I just used a little graphite. The t.b. has work perfectly for over a year now.

 

I agree with the first two statements-
none

People really need to get out of this "its stock so it must be restrictive" thinking. Our MAF, TB and intake manifolds dotn need much modifications for most guys

 

well some of us also have the " its got XX,XXX miles on it so I think it needs to be changed before it goes out" thing so we do it no matter what

 

The AS&M TB has offset bores, and wont line up like stock. You should wait on porting until you decide on which one to get and do the porting once you have a gasket for the TB to match to the intake.

-Tony

 

Yessir I believe they are!

 

Unless your running a blower your wasting your money.

 

I beg to Differ, I never had any problems with my Holley, & the fact that its got closed off IAC passages makes a big cam / split blm issue happy, its also got a very very sexy look to it

 

A Throttle Body with VERY VERY sexy looks?!
Man, you must be VERY VERY lonely.

 

Thanks for the many replies. Sounds like the AS&M is the only one that is significantly off center. And if memory serves, I got that in my head a while back from reading Brent's install guide on f-body.org.
I'd like to wait till I had the t.b. in my possesion but I dont know when that will be and It would be so much easier to port it now while the intake is on my work bench since I'm port-matching it with the heads.

 

Well, if you really want an AS&M, here is a scan of the gasket for you to use as a template

http://www.bfranker.badz28.com/misc/58mmgasket.JPG

As for my comment on Holley vs AS&M. You rarely hear of issues with the AS&M yet several people on here have complained about quality control issues with the Holley. The issues with my own Holley were minor in that all I had to do was grind a stud down to connect the cable. However, others have talked about seeing LIGHT around the blades even when fully closed!?!? How the heck that happens with a CNC machine is beyond me

 

Hmmmm. Ya, that looks like the full size/actual size.

 

I put a bbk 58 mm on my car recently. The increase is modest next to none from what I can tell. I bought it used for $150, so I said freek it. I figure I'll need it when I go with a bigger combo in the future anyway. I say don't waste your money on a new one, buy a used one. much cheaper

 

When you import it into a graphics program and print it, it comes out correctly... at least on my computer. How it looks on your monitor means nothing. You might still be running in 640x480 or "Apple Font" for all I know

 

No probs with my 58mm BBK. It was ported to get the ridges out of it and the motor seems to enjoy the extra air.