APD Carburetors' New Throttle Stop Carburetor
Genoa, OH
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APD Carburetors

Advanced Product Design has been at it again during the off season. At PRI I met with Steve Williams of K&N Filters and he made a statement that stuck with me, “All of you carburetor guys have improved the throttle stop carb but none of you have fixed it.” That statement stuck with me.

Following the show I started working on a solution and the results have me really excited. First off in our new billet line of carburetors we have added an additional circuit just to tune while on the stop. However the real gain here is going to come with a design that I, along with former multi-time NHRA Pro-stock champion team co-owner and current owner of Applied Physics Mike Sullivan have been working on nonstop.  I have always credited myself for thinking "outside of the box", but working with Mike he has shown me what working with "no box" at all is what it is all about. Working alongside intelligent people is a huge part of APD’s success, and Mike is at the top of the list.


APD Throttle Stop Carburetor


This new carburetor design mounts the throttle stop within the carburetor’s linkage and has very positive stops, both opening and closing. I have always felt it is better to shut the carburetor itself than to shut off the air below it. When an under the carb stop is used, it shuts off the signal to the whole carburetor, while an inline stop shuts the carburetor blades and still keeps signal on the idle and intermediate circuits along with having the accelerator pumps to help the motor recover when coming off the stop.  With the designs of the past inline throttle stop, inconsistencies in stop rpm and e.t. came from the pedal stop inside the car along with cable movement and flex. This new design fixes all of those problems. The throttle lever that your cable attaches to goes against a wide open stop and never needs to move to go on the stop. All the linkage is CNC machined from premium materials to exacting tolerances. I believe this new design will become the standard in throttle stop racing as we know it.



Along with our new throttle stop design carburetor we also have developed a line of billet main bodies. All of our testing along with the testing of several customers has shown very promising results. It fits a standard 4500 bolt pattern and is available up to a 2.650 throttle plate. The top of the carburetor has standard mounting for a scoop tray with no need for additional spacers. The throttle shaft bushings are graphite impregnated to stop throttle shaft sticking. This new design has given us the ability to put any venturi we can come up with in the carburetor without any restrictions. These carburetors are also available in alcohol versions.


APD Billet Carburetor Main Body


This past year APD also developed an internal bypass fuel pump requiring one line in and one line out, with no return line needed. In the past I hadn’t been a fan of doing this, but our new design works great, possibly even better than our external bypass style pump. The idle and high side pressures are still separately adjustable with this new design. In testing, these pumps did not spike or overshoot pressures. Edmond Richardson was the first to test this system and his response was simply  “This is a no brainer. Why wouldn’t everyone use this pump?”


APD Carburetors Belt Drive Fuel Pump


I am very excited and feel that 2013 is going to be a big year for APD with the release of all of this new technology. The products above are available for order now with about a 4 week estimated delivery time. I would like to thank all of our customer that have supported us through the years and wish everyone the best of luck with the upcoming racing season.

Feel free to contact us at 419-855-3073 or email us at apdcarbs@gmail.com

- John Kyle -

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