Holley float level sight plug holes

[bill dedman]

I bought two new float bowls for my Holley 4150 double pumper and installed tham only to discover that the location of the float bowl sight plug holes is different, from the front bowl to the back one. Is this anything I need to address, or more to-the-point, why would they be at different heights? What am I missing here???

Anybody got any ideas on this?

Any information will be appreciated!

[BlueOval Ralph]

Just use a 3/8ths drill with the bowl up side down. Seems as I remember there was a difference between the 4150 & 4500 bowls. Are the ones you got drilled and tapped on both sides of the fuel inlets? If they are they are 4500 bowls.

[Ed Wright]

Originally Posted by BlueOval Ralph

Just use a 3/8ths drill with the bowl up side down. Seems as I remember there was a divergence between the 4150 & 4500 bowls. Are the ones you got drilled and tapped on both sides of the fuel inlets? If they are they are 4500 bowls.

I agree. I don't think serious racers use the sight plugs anymore. We didn't in the '70s.

[bill dedman]

Ed,

I'm not a serious racer (as you know,) but neither do I want to run around with float levels maladjusted. I didn't know an alternative way to adjust them...

Thanks for the info.

[bill dedman]

Originally Posted by BlueOval Ralph

Just use a 3/8ths drill with the bowl up side down. Seems as I remember there was a difference between the 4150 & 4500 bowls. Are the ones you got drilled and tapped on both sides of the fuel inlets? If they are they are 4500 bowls.

Yes, I had to move the inlet to the other side of the carb for the applicatiion, so I just bought two new bowls. One of the new bowls has threads on both sides of the fuel entrance. I guess that's the 4500 bowl...

Thanks for the explanation!

[Harry 6674]

They are supposed to be different heights. At least thats they way Holley makes them.
I believe the secondary is higher than the primary.

[bill dedman]

Thanks for that bit of information! I learn SOMETHING new, every day...

[Ed Wright]

Originally Posted by Harry 6674

They are supposed to be different heights. At least thats they way Holley makes them.
I believe the secondary is higher than the primary.

I always use a 7/16" drill bit as a gauge for the primary (front) and 3/8" for the secondaries.

[bill dedman]

Thanks, Ed; I am sure that's good advice! I'll follow it!!!

[BlueOval Ralph]

If its a square carb like a 750 same pri & sec vent and throttle blade size I make everything same float levels air bleeds and jets same