It seems that mixture screws in some carburetors only have a slight effect on the engine; however, the T mixture screw in the Detroit Lubricator Model 51 can really affect how well the engine runs- seems to have a significant impact.

Now running smoothly after valve adjustment- ready to hit the road for test drive. Take a look:

https://youtu.be/SUhkUBWXHV4

Fun collection- thanks for sharing. Keep chugging along!

Fred- yes, generator fixed by AER. No extra parts left over.

Thanks @Greenfield.

Regarding the valve stem clearance issue- After much research and speaking with several valve manufacturers and old school machinists, we decided to just go with the standard .340 diameter intake and exhaust valves from Max Merritt without changing the valve guides. That gave the valves a few extra thousands clearance, which we reasoned was a good thing in the end, since I was having the common problem of sticky valves. There didn’t seem to be too much play with the .340 valves and old guides.

First start!

https://youtu.be/SA75u8SbB-Q

I second the suggestion of calling Scott Henningsen. at pac-carbs.com in Salinas, CA. He recently completely rebuilt my DL 51. He also commented that it is quite common to see these carbs modified over the years. Mine was a hodgepodge mixture of Cadillac and Packard DL51 parts. If your mixture T screw has been messed with, there may be other alterations as well.

Can you post a photo of your carb?

I wasn’t aware of later forged rocker arms- thanks for the tip. I can see why they were upgraded to forged as several of my rocker arms had been welded in the past- you can just make it out in the photo. Otherwise they were in good shape, so we’ll hope for the best. I don’t think I’ll be putting a lot of miles on this old gal.

Making progress.

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We've decided to go with the new valves, both intake and exhaust. Although they are a bit loose, given the sticky valve problem with this engine and lack of oil pressure lubrication in the valve guides, the extra clearance will likely help us. Terry is lapping in the valves to the seats. As the engine deck has been cleaned up, an old weld repair is evident and appears to be intact. We pulled the anterior rockers/cam rollers, and except for a few old weld repairs, they appear just fine, without much wear. I don't think we're going to pull the rear rocker/rollers since we'd have to remove the exhaust down pipe to get them out. Finally, the head has been repainted and looks good.

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