The Stovebolt Site Forums The Shop Area The Electrical Bay Ignition timing and distributor vacuum advance.

As shown in my link the 41 (Betty Boop) is rocken and rollen down the road.
In driving her I at first had a lot of engine clatter (ping or spark knock) i readjusted her ign. timing and reduced it greatly but still have ping. We are running super unlead fuel. And base timing is on the mark. My question is how much advance should this truck have.
1941 216 standard shift. Also is the ball on the flywheel TDC or an advance/ retard of TDC?

Usually the ball on the flywheel is the timing mark. UDC/TDC is usually indicated with a triangle.

disconnet vacume advance when setting timing. sometime even at idle, it will slightly advance, and thus you are off from the get go. Worth a try. Also, since you are already hanging over the fender, pull the cap and check for play in the shaft.

Did not know about the triangle. Is the ball advanced or retarded of the triangle, if so do you know how much?

I believe the ball represents 6 degrees advance. It would pop into the viewing port before any TDC triangle.

Stuart

Cool, would anyone know what is the total advance is?

Toyvo,

I couldn't find any dope on a '41 216 but enclosed is a link to data on a '46. This specs should be pretty similar.

If your rig pings it obviously has to much initial advance...you already know that. Start slowly retarding it until it no longer makes noise when the engine is loaded up and working hard. If it makes no noise and doesn't show any additional engine heating then you have tuned it for maximum initial advance. Total advance will be dependent on this setting plus whatever your centrifugal advance adds.

http://www.secondchancegarage.com/public/359.cfm

Stuart

I keep forgetting that this vehicle was built 68 years ago. Specifications like total advance were not in the origional equasion. Hell they didn't even have a Sun distributor machine untill the early 60's. I guess I'll just have to monkey around with the timing untill I get best performance and no ping. I still don't understand the (octane) adjustment that is calibrated on the base of the distributor. I'll bet it was so you could run the engine and have a referance point to make fine adjustments to the timing as needed.

Toyvo, you've got it exactly right. Thats what the octane adjustment is for.

The conventional wisdom at the time I was learning the trade (mid-1950's) was that the ball and pointer was a starting point, and for best performance/minimum detonation the timing should be tweaked a degree or two at a time until minimum noise and best performance was reached. Use the clamp screw on the distributor housing to set the initial timing to the ball/pointer position with a strobe light, then use the slotted "octane adjustment" to tweak the final setting on a road test. Get on a steady uphill pull in top gear, and listen for a ping at or near full throttle. Advance the timing until it pings, then retard it just enough to make the ping go away. At heavy load conditions, the vacuum advance shouldn't be a consideration- - - -it only comes into effect under light-throttle cruise for fuel economy. As soon as the throttle is opened to pull or accelerate, the vacuum advance goes away. It should not be necessary to use premium gas unless there's something very wrong with the timing setting. That engine only has about a 7:1 compression ratio, and regular gas is good for 8.5:1 or better.
Jerry