Black smoke when heavy throttle..

[Walter Moore]

Could the accelerator pump on the 4 barrel be set wrong? On a down-draft carb there is actually a pump that is actuated by the throttle to literally shoot a stream of fuel into the intake when you open the throttle. (Without this the mixture would lean way out until the system re-stabilized.)

I had a friend back in the 70's who put some huge Holly "double pumper" with mechanical secondaries on his small block Dodge, and every time that he punched it from a stop light it would actually flood the engine with gas and the car would stall. (Followed by him spending several minutes with the hood open holding the throttle plate at WOT and fanning the carb to try to get the fuel to evaporate.)

It is possible to put too much carburetor on an engine by the way.

[CarbonBlack240]

Ok, hopefully this pic will work out better.. And as far as my screen name goes that's the name of the car haha. (It's a long story) But I will check the spark plugs and see what's going on with them and Ill do them one at a time this time .. I really don't want the 4-barrel, I would love to put these carbs on like they were originaly supposed to.. So if ya'll can tell me if I have everything then I can get rid of the old carb.. thanks!

[CarbonBlack240]

Ok... I cant figure out for the life of me on how to blow up that picture... this sucks..

[Bruce Palmer]

[ATTACH]40508[/ATTACH]

Ok, hopefully this pic will work out better.. And as far as my screen name goes that's the name of the car haha. (It's a long story) But I will check the spark plugs and see what's going on with them and Ill do them one at a time this time .. I really don't want the 4-barrel, I would love to put these carbs on like they were originaly supposed to.. So if ya'll can tell me if I have everything then I can get rid of the old carb.. thanks!

From what I can tell you are pretty complete. You can compare to some of the photos on our web site and/or buy the JUST SUs dvd and follow it through the process. we can come up with any of the litle pieces you may be missing.

PT Barnum said something about you'll be able to sell the 4 barrel set up.

[Gary in NJ]

While the carbs look complete, there were modifications to your throttle linkage and fuel delivery to accommodate the Holly 4bbl. You will need to return those back to the original configuration.

[Carl Beck]

CarbonBlack240

Questions:

a) how long have you been driving this Z?

how often have you ran it hard or floored it?

Brown smoke could just be rust from the exhaust system blowing out of a car that sat too long.

Black smoke could just be carbon built up on the cylinder tops and flooring it breaks some loose.

The image is too low a resolution to blow up much.

The Carb's pictured are S.U.'s manufactured under license by Hitachi.

Even or uneven Air/Fuel distribution from a single 4 barrel, to an inline six depends upon the design of the intake manifold. {the length and diameter of the runners etc have to be finely tuned, no reason distribution can't be even to all cylinders}.

FWIW,

Carl B.

[JohnnyO]

+1 on rust in exhaust. Experienced that first hand.