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Joe, looking at the photo of the carburetor I notice that the air cleaner seems not to be fit correctly, at least it looks that way to me. Looks like the air cleaner needs to be pushed down more on the carb. The top of the slots in the cleaner are not covered and will allow air to bypass the cleaner which will let in unfiltered air.

Good find on the battery powered timing light.

(o{}o)

Thanks, JayDub,

Until I had the new timing light and adjusted the timing, the car was hard to start, so I was having to lift off the air cleaner to be sure the choke was open half a dozen times. I wasn't paying attention to it being fully seated. Now it starts great, cold and hot. The brace for the air cleaner is cocked in a way that tilts the whole thing, so I have to twist the air cleaner while tighten the hold-down screw to get it straight. I'll have to remove the brace to adjust it.

In the meantime, I've got the air cleaner seated properly.

Tonight I'm going to adjust the linkage, which seems to be very different between the '48 Carter carb and the '40 Stromberg.

I really appreciate your observations.It's one reason I post a lot of pictures, obvious as many of them must be. I get feedback. "Hey, Joe, I noticed that your ______(name of item)_____ is installed upside down. That may account for the engine's ______problem____.

CARBURETOR/AIR CLEANER COVER. JayDub, I, too, thought those little holes were letting air in because the air cleaner wasn't down enough over the carburetor horn. But it was. And the lip or seating height of the Carter carb and the Stromberg are the same, so not sure why there would be vents. I mean they built this humongous oil bath air cleaner. The slits in the air cleaner appear to be there so you can cinch it up tight. Still they didn't close up, so I covered them with a strip of black electrical tape.

I have a bigger problem.

DIFFERENTIAL RATIO: The problem with my speedometer reading correctly is due to 2 things. 1. I have an ambulance rear-end and 2. I have the wrong speedometer pinion gear. The reason I have the ambulance rear-end is because I broke an axle in 1975 and the ambulance rear-end was the only 1940 one available locally. When I called Don Figone to see if he had a 20-tooth pinion gear that might correct my speedometer, he didn't have one, but suggested putting in the correct 1803 rear-end. I started looking for one among the usual suspects. The flackmaster suggested just replacing the differential. So that sounded like a much better idea (and probably what Don was actually recommending).

I spent some time today reading up on gears and came across a video on determining the differential ratio. From the parts manual I had numbers like 4.7, 4.9 with OD, 5.22:1 for 120 Ambulance and 4.54,4.7with OD for the 160 Ambulance, and finally 4:36 for 1803 with OD. Other 1803 could 3.92 std or 4.09 spl.

So you put a piece of tape on the wheel and a piece on the drive shaft. The car is jacked up on stands and out of gear. As you rotate the wheel, you count how many times the shaft goes around and you count the number of times the wheel makes a complete revolution as you go until the wheel has gone around 10 times. Then divide by 10.

I was a little shocked when the shaft had only gone around 2 times and the wheel was already 1 revolution. I finished this anyway and made 20.5 shaft revs to 10 wheel revs. So my differential ratio is 2.05:1?

I obviously missed something, so when you're finished laughing, please tell me where I went wrong. I'm sure it's something simple.

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I think you need to hold the other wheel stationary. Otherwise your differential (that allowes the wheels to turn at different speeds when you go around a corner, or do one wheel burnouts) messes up the counting of your ring and pinion ratio.

Thanks for the input. Here's the video I watched.

https://www.youtube.com/watch?v=2y9iqvO7RaU

I won't say this guy is a great authority judging by some of the comments under the video, but both wheels are turning in his video. I think we need another opinion.

Only raise one rear wheel. Count the driveshaft turns to rotate the tire 1 full turn and multiply that by 2.

Thanks, Dave,

But I have news for you. The result is the same, except for being less accurate because I only sample 1 wheel revolution instead 10.

The shaft turned 2 times for 1 revolution of the wheel, after I pulled the jack stand on the passenger side.

If you watch the tail end of that video, he doesn't multiply by anything. He gets 39 shaft turns to 10 wheel rotations and divides by 10 for a 3.9:1 ratio.

But what you're telling me is that my ratio (using my 20.5 rotations) is close to 4.1. The closest ratio is a special 1803 differential with 4.09.

Is the difference that he has Positraction or something?

Looking back at the parts book, p 260, 12.005, 1935-1941 Parts, for the 1803 I see:
900131 3.92 Std 1803 - 6 - 1903 - 6
900065 4.09 Spl " and the 1804,1807
900064 4.36 Spl used for Econodrive with all above

The higher the number, the lower the gear (another issue for me). So my 4.09 differential gives me more speed per engine RPM than the recommended overdrive differential of 4.36.

So I'm thinking I should keep the 4.09 (since I can always kick down into 3rd under if I need more torque up the hill.) And it also means I need Fewer teeth on the speedometer pinion. Like 17.

Edit: Don corrected me. For OD cars with 4.09 the gear is at the bottom of the shaft, so I've corrected the number below:
In fact, on page 49, 3.257, for Speedometer pinion and shaft, I see:
354976 for 4.09 differential with OD, 17 teeth

Don does not have a 354976, so checking around for one, starting with John Ulrich.

Even though I believe my problem with the speedometer is solved, I'd still like to understand your formula, Dave. It is correct, but why? And why is the other guy correct, too?

Is the difference that he has Positraction or something?


Yes.

And of course if you do it 10 times and then divide by 10 you may have a more accurate result.

Thanks, again. It all makes sense now. And when I'm going 70, my speedometer will reflect that...and I'll see the color change to red at the high end on the speedometer pointer. I can't wait.

West,
I'm still considering whether to add my trunk rack to the car or not.

The issues I have:
1. Have to sacrifice the shield emblem I really like. One of the classiest items on the car.

2. I would sacrifice the Packard "engraved" bumper, that answers everyone's question just as it comes out of their mouths, for a plain bumper with extra holes.

3. Alternatively I could keep my bumper and remove the bumper guards completely since they get in the way when the rack is down. I'm not sure I like moving them them to a rounded corner.

4. I suppose the bumper could be drilled to move the bumper guard between the bumper bracket bolts, but I know they are made of tough steel.

5. There's also some issue about the word Packard on the license light I'd have to add to the trunk lid above the rack. IMHO if it doesn't say Packard on the bumper, it ought to say it someplace, but I've heard it's wrong for a 1940.

6. And I'd have to find a plain trunk handle instead of the lighted one whose design seems more in keeping with the other handles on the car.

7. I don't have a trunk.

The last time I entered my car to be judged was at the Cottage Grove car show the Sunday the astronauts walked on the moon in 1969. I'd spent the morning polishing everything I could only to overhear one of those tail-pipe peeping judges say, "Well, Charlie, it's restorable." It's a good thing I'd already had a couple of G&Ts. What I'm saying is I'm sensitive to vehicular correctness. But I wonder also, on a 1940 built in the summer of 1939, if all the 1940 differences were implemented.

We know that a couple months into 1940 changes were implemented. Hubcaps. Addition of the 3 moulding strips on the wheel well covers. Wood grain pattern. Interior door upholstery pattern. Possibly some other things. So maybe, and here you can see I'm building some kind of rationale for doing what I want, they used up some 1939 parts, like the license light glass. The trunk rack bumpers I've seen don't look like 1940 bumpers. They're not pointed on the ends and their surface is rounded. I wonder if a 1940 front bumper could be modified to satisfy judges who think Packard script on the bumper with a rack is wrong.

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