Take a look at this and satisfy my curiosity

[geoffinbc]

Ok in the picture below is a typical 2.8L manifold. Now my theory is to rip out the whole middle section dividing the throttle bores.

CFM Tech claims their throttle body spacers increases power above all others because each side of the engine can draw from both bores. This makes sense since almost every carburetor you see has this feature. So why not take it a step further?

So what do you think? This is a spare manifold so why not?

[RacerX11]

RE: Take a look at this and satisfy my curiosity

This is why I refer to this TBI intake as a dual-plane intake. Half the cylinders pull from half the TBI, just like a dual-plane carb intake. Opening it up so that each cylinder can pull from the whole TBI will increase top end power, just like using a single-plane intake.

It won't be very easy. The coolant passage surrounds those throttle bores. I'm not sure where they stop, so it will be hit-or-miss when you cut out the middle section whether or not you cut into the coolant passages.

I am achieving a similar end result by starting with a carb intake, hogging it out, and attaching a TBI mounting plate for a 350 TBI.

Marty

[firechiken]

RE: Take a look at this and satisfy my curiosity

If you don't want to play around with yours, or risk f'ing yours up, I can get one of mine into the milling machine at work tonight and see what happens.

[geoffinbc]

Well I know what you are saying there. But a true dual plane (at least as I see it) will have the bottom deck of one side different than the other. Also the ports will be divided up and half (2 on each side of the V) will grab air from the higher side and the other half will grab from the lower side.

It would be interesting to see what happens. There are no water jackets between the bores they only go around the outside. The only thing between the bores is the vacuum port for the booster.

If I could get that bitch to breathe better at high RPM then im all for it. So im gonna try it and see what happens.

[geoffinbc]

Re: RE: Take a look at this and satisfy my curiosity

If you don't want to play around with yours, or risk f'ing yours up, I can get one of mine into the milling machine at work tonight and see what happens.

Hey if ya want go for it. I'd like to see what happens. I know there is no water jackets between the bores. Oh and one tip. Be sure you zero your head to the top deck because it is not parallel with the bottom

[RednBlack]

If you are going that far, might as well go all the way and make it high rise. Get some real top end. Making a high rise spacer to add to the open plenum? Hmmmm.....Just a thought. I'm doing basically the same thing, only different.

[firechiken]

Alright, I'll get pics, too.

[geoffinbc]

Mint

[geoffinbc]

Here is what I was up to on friday. Removed the riges around the throttle bores. It is suposed to increase air flow. It looks just like a holley TBI now.

[firechiken]

Well, it looks like racerx11 was right. Big 'ol coolant passage on the back side.

[tejohnson]

Would it be possible to over bore it and weld in some type of sleeve? I'm sure this wouldn't be too hard to make using a 1/16" sheet, but I'm certain the welding would be interesting

[firechiken]

You'd have to weld it top and bottom, which would be nearly imposible. I was thinking counter sink a plate over the hole and weld it in. That would be difficult, too, because of the vaccum port right underneath. There's not alot of meat seperating the two. There is also a vaccum port directly across from this which was cast downward into the plenumn, but it should be alright just coming straight in.

[geoffinbc]

Woah shit I didn't think you were gonna take that much out LOL.

Below is a CFM-Tech spacer. I wa thinking about removing a similar amount to what they have there.

[firechiken]

It was already bored out for the 4.3 TB before I realized it was junk, so I just went side to side. Your pics didn't come up, but I'm assuming that there's only like an inch taken out of the middle? I don't recall where the passage started in relation to the centerline of the bores, and I don't have another junk intake to find out.

[geoffinbc]

Yea I guess thoes bores are a little big LOL. I guess if I try it I will have to stear clear of that little freeze plug and I should be alright.

I have the shaft outa my TB right now (the one shown above) I am gonna install sealed roller bearings at each end to seal it 100% from vacuum leaks. I am gonna mod the shit out of it and see how good it can be. Then if all goes well I will apply the same to my 4.3L TB in time for the supercharger.