Quote:
Originally Posted by RockHillWill
DJ: Another thing that I am concerned about using an inlet balance tube is that unlike the exhaust system, the intake system uses the vacuum to move the inlet charge. By adding a balance tube at any location, or using a tube of any diameter, it will increase the inlet volume, and by maintaining the same inlet vacuum it would result in a slower acceleration of the fuel charge, resulting in less fuel to those cylinders. Your thoughts?
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The first time I tried too chock down the balance tube was on a 1275
Sprite / Midget for SCCA. It had a stock BMC manifold with SU's and killed
the "low speed" drive-abilty. I started opening up the holes in the tube till
we had a happy balance. He also ran auto-cross's which really showed the
problem..
The second time was in a restricted class. Short track paved stock cars,
ported iron 2 barrel intakes(Brzezinski) with a Holley 350 2 barrel. I made the Aluminum adapter (2")and and match ported it both ways. Same thing.
I ended up cutting a transfer slot on the top side of the adapter too improve the low speed,...like your coming down for the first "Green". Hell,
I even "fudged" and put a 500 baseplate and reworked under the venturi
too match things up.
I've noticed it in the Weber set-ups (4 carbs on a downdraft) in Can-Am
before fuel injection. Also in the Hilborn type manifolds (alky) in the
Super Modifieds.
Sooo,..this got me thinking. The 4 cam Ford Indy engines, gas or alky,
ran a booster venturi,...which I'm sure was there for the low speed part
of the RPM range...need a photo? Remember, some of those cars ran
2 speed Halibrand's at Indy!
I think it needs the pulse from the other manifold at low speeds..
I know your worried about it being "lazy",...I'd think about the "double
venturi" from the E-28 carbs...that could hop it up some on the bottom
end? This would be after you run a base line with what you have.
Balance tube..?...how about a spacer(s) between the carbs and the
manifolds,with a tube,...just too see if it changes anything ?
Dudley