I want to get a better TBi unit. However, I called them today and they said they bore it to 1 13/16" and stock is 1 11/16". There would be an eight inch difference between the TBI bores and the bores in the manifold. I do not want to take off my manifold and bore it. Anyways, that leaves a 1/16" lip for the air to flow over into the manifold. Would this cause problems. meaning, could this actually hinder performance and not allow the air to enter the manifold smoothly?

 

yes

 

the turbo city stuff is nice, but for the price you can take your time and do a good ultimate tb and get just as much performance and not spend the money.
the lip that the turbo city tb leaves causes interference in more than jus tthe over lapping area. since the air will basically have to stop and make apair of 90degree turns to get into teh intake it will force the surrounding air to slow down to allow it in. this cause a major loss of velocity and volume that will only grow as teh rpm's and attempted draw velocitites of the air rise.

later
tim

 

Something else to consider....The blades on the throttle shaft will not be able to open since they will be bigger than the bores in the intake.

 

91_hd,

That is a really good point and I never thought of that. I do have a half inch spacer. I was thinking I could have it milled to be 1-13/16 up top and 1-11/16 at the bottom. Kind of like a cone shape reducer that will allow air smoothly into the manifold. I'll just stick with the ultimate TBI.

 

going through all that trouble for barely any more flow is really gonna be a waste. you may pick up a few horse power, but nothing that can justify spending that much money. you would be better served to save a little longer and get a holley tb and a different intake.

later
tim

 

They will be able to open because the blades are elevated above the top of the manifold, so the chord of the blade that shares the same plane as the top of the manifold will be considerably less then 1-11/16.

 

What about having them taper bored down to the butterflies, its an old tricjk we use on injected banshees.

 

I'm using the Turbo City Ported Throttle Body on my 350.
It looks good and the lip (NJ Speeder was referring to)
has been removed. Looks like the whole thing was polished in a
vibratory tumbler or something.
I did have some problems with mine, however:
1) The bottom of the TB was very warped, causing a vacuum leak that would get better as it warmed up.Rather than send it back, I ended up just hitting it with a large block of steel, wrapped with sandpaper until the whole bottom was shiny.No more leak.
2) One of the rear vacuum ports was bent pretty far.I assumed this was to make it easier to install the AFPR, but it actually was in a position that would not clear it at all. Had to re-bend the tube in the opposite direction, and luckily did not break it.
3) Also, they don't advertise the fact that after you get their TB,
they want to have the $$$Core in ten days.Had to scramble to get them a core, as I wanted to keep my original (because I knew it was a good spare).

It works great, and my TBI 350 made over 300 HP on a dyno, but I feel for the money, they should have better quality-control.
As far as the bigger bores and an intake manifold goes:
I'm using the Edelbrock Performer TBI and following their recommendations (and Turbo City's ) I chamfered the upper 1/8"
of the bores and there are no clearance issues. Yes, I'm sure it would probably flow better on a manifold that is sized accordingly,
but I'm satisfied with the performance so far (whipped one of those new Roush Mustangs yesterday, and a Cobra a few weeks ago).I'm also using the Turbo City AFPR and it's a nice unit.
Easily adjustable from behind the TB, with only the Air Cleaner removed.
-My 2 Cents-
-Rich-