Automatic Centrifugal Timing Device
- Thread starter Fred Ryan
- Start date
nkaminar
Well-known member
The required advance curve is unique for your engine. It depends on many factors, such as the compression ratio, the mixture, and the engine load. Modern engines have many sensors and a computer and constantly change the ignition advance. In my experience, the computer under my hat does a pretty good job (not perfect) of adjusting the ignition advance. It does take some experience.
petew
Senior Member
The timing lever , throttle lever and GAV are some of the things that I love about a model A .
I have spent countless hours changing advance springs and messing with timing on muscle cars and hot rods . With my model A I can just sit in the car and do all of that and fuel mixture as well ! Kind of makes me feel like part of the machine .
I know that Collin (Alexiskai) has a lot of experience with the automatic advance devices so if he says they work than I believe him and it is probably a viable option .
I just love levers and knobs ...
I have spent countless hours changing advance springs and messing with timing on muscle cars and hot rods . With my model A I can just sit in the car and do all of that and fuel mixture as well ! Kind of makes me feel like part of the machine .
I know that Collin (Alexiskai) has a lot of experience with the automatic advance devices so if he says they work than I believe him and it is probably a viable option .
I just love levers and knobs ...
alexiskai
Well-known member
Nice coupe Pete
One thing I like about the Nu-Rex centrifugal advance is that it's a mod that was specifically invented for Model A by one guy. His name was Frank Williams, and he worked in the auto industry in Boston. He started developing a centrifugal advance for the Model A in 1928, receiving a patent for the design in 1930. He contracted with F.C. Phillips to manufacture it. Within a couple of years he had sold his interest in the device to Phillips, which rebranded it with their name. Eventually the device was discontinued, before it was revived by Nu-Rex.
Frank's design was an elegant solution that used the empty space in the valve chamber in a creative way. The only element that changed significantly over the invention's lifespan was the flat spring design. In the original patent, you're supposed to rivet the spring to the valve cover – not a great idea. The Phillips design used a spring with a tab cut out of it that braced against the top of the valve chamber. Nu-Rex further improved this design using a semicircular spring that braces against the top of the chamber in two locations.
An additional element of the original design that didn't make it into the final product is that the collar, which was grooved to shape the timing curve, could be removed and rotated to switch to a different groove, which produced a flatter timing curve. This would have been useful for engines modified for racing. I assume it was cut for cost reasons.
Anyway I like the Nu-Rex device because it works great and it's an original mod that represents one guy's vision of how to improve the car. The tradition of modifying the A in various ways to suit your personality is as old as the car itself. Most of us do it to some extent. If you don't like this mod, don't use it.
alexiskai
Well-known member
Here is the portion of Frank Williams's patent describing first the riveted flat spring and second the adjustable timing curve.
Attachments
When I bought my Model A I had problems with setting the timing. I was told to do it by the sound and feel of the motor. Well, I have a hearing loss and wear hearing aids that doesn't always allow me to hear the things that people with normal hearing do. Guys who wear hearing aids know what I'm talking about. Anyway, I bought an automatic centrifugal distributor and installed it and love it. Had it for two years without a problem.
Brentwood Bob
Well-known member
Easy to time with the point cam wrench supplied by nu-Rex, helps to know that the engine has that automatic advance installed. Using the hand lever if the engine is so equipped is not recommended by me.
Bob-A
Well-known member
Gene F
Well-known member
I'm curios, if you use the spark advance handle and push it all the way down, approx how much advance is that in a typical engine? I.e, so 26 would be about 2/3 of the potential used?
Y-Blockhead
Well-known member
Depends on where you set the initial timing. The Nu-Rex (Phillips) auto advance, advances 30°. I set my initial timing at ~5° ATDC and the spark lever locked to limit my total advance at 28° BTDC.
If you set your timing as original, 0° TDC then pulled your spark lever all the down, as you ask, you would have ~70° advance!!
When I set up the nu-rex timer I did it this way.
Timing needs to be adjusted to have 4 degrees less timing.
This car is equipment with a Snyders 6.1 high compression, part number Part # A-6010-HC6, and a Nu-Rex automatic timing advance system, Part # A-12176-X.
For the car to be properly timed with this hardware you need to:
1: First, advance the timing lever down 1 notch (about ¼” down)
2: Then, find TDC using the timing pin as usual.
3: Set the timing per the normal procedure.
4: Bring the advance lever to the full up position, and while starting or driving, DO NOT TOUCH THE LEVER AGAIN.
Timing needs to be adjusted to have 4 degrees less timing.
This car is equipment with a Snyders 6.1 high compression, part number Part # A-6010-HC6, and a Nu-Rex automatic timing advance system, Part # A-12176-X.
For the car to be properly timed with this hardware you need to:
1: First, advance the timing lever down 1 notch (about ¼” down)
2: Then, find TDC using the timing pin as usual.
3: Set the timing per the normal procedure.
4: Bring the advance lever to the full up position, and while starting or driving, DO NOT TOUCH THE LEVER AGAIN.
alexiskai
Well-known member
FWIW, I have mine timed at about 5° ATDC initial timing and I bring the lever down half an inch for start and cold idle, which corresponds to roughly 10° BTDC. Then I bump it back to the top when I get on the road. It just helps keep her from stalling. With a healthy starter and battery, you absolutely can start a Model A at 10°, 15°, or even the infamous Model B 19° BTDC initial timing.
Bob Bidonde
Well-known member
If you are running a stock 4.2:1 compression cylinder head, and you change your modern motor oil regularly, the automatic spark advance accessory is a worthwhile accessory. I have found a few of the original automatic spark advance gizmos on engines over the years. Most were not working because the flywheel was stuck by sludge. However, I admire the engineering concept.
Many many Model A'ers run hi-compression cylinder heads that do not require the amount of spark advance the stock head does. So the automatic advance gizmo may be the cause of spark knock if running with a hi-compression head. Also, running the automatic spark advance with hi-test gasoline may cause spark knock.
My preference is to fine tune my engines to the running conditions each time I take the cars out for spin. I do this with the spark advance lever and the GAV. Both of my A's have hi-compression heads.
Many many Model A'ers run hi-compression cylinder heads that do not require the amount of spark advance the stock head does. So the automatic advance gizmo may be the cause of spark knock if running with a hi-compression head. Also, running the automatic spark advance with hi-test gasoline may cause spark knock.
My preference is to fine tune my engines to the running conditions each time I take the cars out for spin. I do this with the spark advance lever and the GAV. Both of my A's have hi-compression heads.
alexiskai
Well-known member
Why would this be true? High-octane gas reduces knock, that's literally the only thing it's for.