Motorsports Village

Grumps Dominators
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Author:  Ron Gusack [ Sun Nov 25, 2012 11:53 am ]
Post subject:  Grumps Dominators

Anybody know why Grump used side hung bowls on his Dominators back in the day?

Author:  scoop [ Sun Nov 25, 2012 12:14 pm ]
Post subject:  Re: Grumps Dominators

He used to like to play alot with the fuel bowls. I know the guy who has his old carb bench. Has alot of homemade stuff to test fuel bowls and how things like fuel pressure and g-forces affected the fuel. Bob J

Author:  shrinker [ Sun Nov 25, 2012 1:51 pm ]
Post subject:  Re: Grumps Dominators

I know why, because side hung bowls flow more fuel and have better surface tipping characteristics than center hung bowls when used in a twin sideways mount configuration. They also have better anti foaming with that box thing around the N&S. The fuel pressure limit is higher for them too.
I've tested just about everything over the years and I am always amazed at what people actually get told is good that isnt.

The problem in a drag car with centerhung bowls is when the carby is mounted sideways it's always working like its cornering at massive G's, what happens is the fuel level in the front metering well DROPS too much. The level in the rear well goes high but that doesnt effect the mixture as much as the drop in the front well. Basically it's easier for the air to bleed through the e-bleeds when the fuel level drops. This leans out or enrichens that barrel, depending on the amount air bleed in the style of emulsion and the actual acceleration verses fuel consumption of the car. A car with high acceleration but low fuel consumption eg a light car, may only lower the level enough to place the head of fuel in the well at the lower bleed thus the carby will react like the top end tune. If the car is a heavy sucker and has lots of fuel consumption for its acceleration and the fuel system doesnt keep up the head in the main well will be right down the bottom because the fuel level in the bowl may be basically sitting on the bottom too. So that situation will make the barrel run lean as the emulsion air will dominate the booster flow. So what happens is dependent upon the fuel level in the bowl and the angle of the fuel surface due to acceleration. The angle of the fuel surface determines the head of pressure upon the main jet and the filling rate of the mainwell etc.
The rear barrels where the level goes high have no chance of getting the bleeds uncovered so the rear barrels struggle to get emulsion air, It happens but its later in the CFM range. Thats why its important to have your jetting done by the main jet and not by emulsion air.
The sidehung bowls have a rounded float which allows the fuel to go up the side of the float and not smother it. Thats why there are corner cut off centerhung floats so that the cornering doesnt shut the fuel supply down. When I tested the variables the side hing float maintained a more stable head in the wells.

When using the sidehung bowls in a normal mounting situation (not sideways) the rear bowl is better being a sidehung because the back wall is closer to the metering block thus its more stable in the rear well head.

Author:  Ron Gusack [ Sun Nov 25, 2012 4:30 pm ]
Post subject:  Re: Grumps Dominators

This shot shows the center hung bowls on 4150's. This is his Monza which was a few years later than the first pic. The first pic was from his 70ish Camaro.

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