Drop Base for Holley 4150

[Bobcat]

I`ve been fighting poor fuel distribution and a carb that just wouldn`t respond to changes like it should for quite a while .
Because of very limited underhood clearance , I couldn`t put just any filter setup on it and the spun aluminum ones were all that would fit . However , the problems with them were insufficient vent tube clearance and a very steep wall behind the element that made the air do some really horrible turns which created a lot of turbulence and other undesirable things ... all of which affected carb tuning badly .
I was talking to a carb man who is one of the best in the country and he said try the Chevy L88 air filter base . Seems he had done a lot of testing and found it to be about the best out there . I did and found that those guys really did know what they were doing back in the `60`s . That base is one of the most efficient units out there , has more drop than the spun aluminum units , correct flow paths ( no steep walls ) and required minimal rework to fit the 4150 .
Basically , just cut off the PCV tube on the bottom and plug it ( hits the accelerator pump arm ) and open up two slots . Clears all linkage and fuel lines and allows me to run a full 3" tall element and have about 3/4" to 1" vent tube clearance to the filter lid .
Carb responds to jet changes the way it should , seat of the pants power is better in all rpm ranges and fuel distribution is where it should be . Car is much smoother at low rpm ( 2200 to 2400 ) also .
All this for about $69 !!
If anyone is interested , I can put up a few before and after photos .

[Rick Parker]

One of the best improvments is to utilize their (or Pro forms) HP main body, with the nice radiused paths into the venturis and made without a choke housing. That alone is one of the best improvements for a Holley. Attempting to utilize a Holley with a functioning choke with a low profile air filter is a futile exercise.

[Bobcat]

Rick ... I agree , but this carb is a Pro Systems HP950 with all the bells and whistles , and no choke or choke tower . Also , everything is radiused into the venturies etc . Still had problems and once I got the proper air flow path and vent tube clearances , everything started working . Even with what Pro Systems did , tuning with the spun aluminum base was an exercise in futility .

[Seagull81]

How about some pictures and part numbers?

[GLS-BDR226]

Nick A. sells a nice drop base package that includes K&N filters. Great package for turkey pans and clearance issues.

[hawk 325]

Where did you get the air cleaner from and what filter did you use?