Dyna S timing.....

I was wondering the same thing. Why would they be firing at different times?

I thought about this for a minute or maybe more.

What kind of timing light do you have?

Find one that has a resetable scale on it. You don't need to find another anything maybe.

Look up in your manual and figure out what your total advance should be. At the highest RPM.

Hook up the adjustable timing light, and rev engine to indicated RPM.

Use adjustable feature of timing light to set timing, using "t" mark as trigger reference point.

To explain:

Do this at idle speed you can see what I mean.

Say you set scale at "0"

Align "f" and stationary pointer.

Roll scale to "5".

"t" mark will "move"

Roll scale to "10"

"t" mark will "move some more"

Your manual will tell you what base and total advance should be.

At idle, if five degrees, rolling scale to "5" should place "t" mark under stationary pointer.

to the next level. . .

Total centrifical advance at maximum RPM, coupled with scale indication of same amount, should place "t" mark under stationary pointer.

After seeing how useful an adjustable timing light is, you will never go back to something as archaic as a a fixed point timing light.

loudhvx wrote:

Does anybody know why the older advacner shows such a small distance from T to F while the newer one shows a wider range? Are they for different motors? I wasn't aware the difference was so great.

Newer style marks are at F=20° and 40° degrees. Older style is F=5° and 40° at full advance but there is no line for full advance on the older style.

bLodi wrote:

here is the pic...

If the springs are stretched or the advancer is sticky it will not be possible to time correctly using the F mark. This is the newer style 76+

From filebase - Exhaustive Development History ---


ALSO IN JANUARY 1974, THE AUTOMATIC TIMING ADVANCER WAS MODIFIED ALONG WITH THE CARBURETTORS. THIS WAS IN AN EFFORT TO INCREASE PERFORMANCE.
TIMING WAS NOW TO BE SET AT 20 DEGREES BTDC @ 1500 RPM INSTEAD OF 5 DEGREES BTDC. A NEW ADVANCER UNDER THE PART NUMBER 21148-005 WAS MADE AVAILABLE AS A DIRECT SUPERSESSION.

STILL IN JANUARY 1975 AND A SERVICE BULLETIN ADVISED THAT ANOTHER MODIFICATION HAD BEEN MADE TO THE AUTOMATIC TIMING ADVANCER.
PUNCH MARKS HAD BEEN ADDED TO THE FACE OF THE UNIT TO ASSIST IN SETTING THE TIMING WHEN FULLY ADVANCED. THE PART NUMBER FOR THIS NEW PART REMAIN UN-CHANGED. THE MODIFIED ADVANCER WAS FITTED TO ENGINE NUMBERS Z1E-058727 ONWARDS.

Well I went ahead and set the timing again when I got home. I was able to get it to hit the F mark on both pickups without is being all the way advanced this time. So I took it out for a spin and it seems to be running pretty dang good. Feels good at idle, low RPM and really pulls up high. A little weak from about 4.5K-7K though...but that could be me needing a valve adjustment or a carb tuning issue. Thanks for all the help guys. Still is kinda a mystery advancer though....