Steve
Here is some good reading material.
http://www.fordmuscle.com/archives/2000/03/timing/
Here is the Shop manual page for the ignition advance curves.
http://www.tigersunited.com/resources/wsm/wsm16.asp
I guess if you have 12 lbs vacuum you have a bigger than stock cam
in your engine but you should be able to get 16 degrees advance with that
vacuum. You are definitely not getting much advance from your current
vacuum canister; you should change it. Some of the early vacuum canisters
were adjustable; it is possible that someone shimmed that canister to only
give 8 degrees advance. Test it with a hand vacuum pump and see if it will
hold a vacuum.
Also an easy way to run the vacuum advance curve is to pull a vacuum
on the canister with a hand pump while the engine is at idle. Be sure to
plug the vacuum line to the carb and a dial back timing light works real
nice here to get the timing.
Ron Fraser
-----Original Message-----
From: owner-tigers@Autox.Team.Net [mailto:owner-tigers@Autox.Team.Net] On
Behalf Of Tigerman
Sent: Monday, January 29, 2007 5:23 PM
To: Tiger List
Subject: timing advance
I remember a couple of threads on here concerning timing advance & timing
curves, so I thought I would consult the collective wisdom.
I am starting to play with the advance curve on my mustang and when finished
and happy with the results, I will try to replicate on my tiger too.
I am about to replace the springs in the distributor to see what difference
in the advance curve I will get. So I made a chart of my initial factory
advance at various rpm's and found that I was 'all in' mechanical around
3500 rpm. Based on what I have read, I want that to be closer to 2500-3000
for better performance. I will have to see how big of a difference the
springs make.
But on to my real question, as well as checking my mechanical advance, I
also checked my vacuum advance, and found I was getting very little from the
vacuum advance. While I realize this is more about fuel economy at cruise
speed, it would be nice to get a feel for what an appropriate amount of
advance would be for the vacuum advance and at what vacuum it should be
applied at. Any guidance? I thought I remember reading once that 20
degrees of vacuum advance was about right, but that is significantly more
than the 8 degrees additional I have now at 15lbs (and more realistically,
my engine probably makes more like 12lbs of vacuum in the real world, which
would only be 5 degrees additional advance).
So what do you guys think?
Thanks,
Steve
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