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I'm trying to adjust a Detroit Lubricator Model 51 udraft carburetor on my '32 902.

The carburetor seems to work OK but when cruising at no-load like on a fairly straight road at constant speed, the engine seems to miss or hesitate. Maybe it's not quite 100% at other conditions but it's noticeable at this no-load. The carburetor is a new repro made by David Frear.

There is a mixture t-handle adjustment screw under the throat. Does that adjust idle or high speed? How should I adjust that?

And there's two screws on the throttle for the butterfly. I'll try to post a photo. One bigger screw seems to be the stop for idle speed. But there's a smaller screw next to it that's called a "kicker screw". I don't know what that means or what that does. It has a needle-like end and is supposed to be adjusted 7-15 thou from being flush with the pump body. Again, I don't know what that means. How do I adjust that?

Could someone give me a step-by-step procedure for adjusting a DL Model 51?

Thanks --- Scott
dwyer12180@gmail.com

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Scott, you must have ESP because I was wondering the exact same thing yesterday! The 903 I'm working on idles beautifully and responds perfectly when I rev the engine, but as soon as it's put in gear and you try to drive it, it dies after a few seconds. However, if I turn on the electric pump it'll drive ok, but it obviously runs very rich. Couple of things to note...

1. I just rebuilt the fuel pump and it's operating perfectly (zero fuel leaks and no air is getting in).

2. The eccentric that pushes the fuel pump rod up & down is worn down approx 1/16". From the factory, they're supposed to lift it 5/16" but mine only travels 1/4" (.240" to be exact). So I acknowledge that this could be the problem but before I go through the enormous process of replacing the eccentric, I'd like to ensure the carburetor is adjusted properly so I can rule it out as the cause (or significantly contributing) to the problem.

That being said, I spent hours online and the only thing I found was what the T-Handle at the bottom is and how to adjust it. It's the air fuel mixture screw and the best adjustment procedures I found are contained within the 1930 and 1931 Owners Manuals. You can find them here on the Packardinfo website.

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Thanks for the suggestion about the 1931 manual. Odd that the 1932 manual says nothing about carburetor adjustment. The carburetor is the same, for all practical purposes.

Also odd that the 1931 manual says nothing about how to adjust that "kicker screw" or even what it does. In fact, the 1931 manual doesn't even label the kicker screw on the drawing !

--Scott

I wish I knew why too. All I can tell you is to keep beating the drum. Have you tried posting this question on other sites?

Have you considered contacting the Carburetor Doctor? Extremely knowledgeable, regular contributor to AACA forums on carburetor questions. Perhaps a long shot but worth the few minutes it takes to formulate an email to him.

doc@carburetor.ca

Adjusting the fuel level is one important area that will help the DL function properly. Checking to make sure the arms that connect the air box vanes to the main jet are not worn excessively is another.

Fuel level can be checked with the DL off the car. I've found it easier to do it this way, vs. on car adjustments. Fuel pressure should be the same as what will be supplied by the mechanical or electric pump.

Original Stewart Warner fuel pumps will typically supply 1.5 to 2.0 psi. Electric pumps are typically higher.

Instead of using gasoline, I've used mineral spirits as a test fluid, safer that gasoline.

Most DL's have a drain fitting on the bottom of the bowl casting. I've made up a fitting to screw into this after removing the drain fitting. The fitting is drilled thru with a small diameter piece of clear hose attached to it. Leave the free end open and make sure the end of it is higher than the top of the bowl and firmly secured so it will not drop down.

If you turn over the engine or start the electric fuel pump you can check to make sure the fuel level in the bowl is correct by measuring the distance between the fuel in the clear hose and the top of the float bowl.

Part sources, link to additional info.

http://www.classicandexotic.com/store/c-387-detroit-lubricator.aspx

https://pac-carbs.com/collections/carburetors-1

http://www.thecarburetorshop.com/PartsDetroit.htm

https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=14609&forum=1

The kicker screw holds the throttle open slightly when the choke is activated. There is a flat spot on the side of the top end of the cylindrical accelerator pump housing. The screw rides on the face of this flat spot during normal operations. However, activating the choke turns the cylinder on its axis, thereby rotating the flat spot away from the end of the kicker screw. The screw then rides up onto the curved part of the housing pushing the throttle slightly open.