Steve, (from Steve)
I purchased a Ford vacuum advance timing kit from Accell. It had a
selection of springs. I found a mechanic who still had a vacuum advance
equipped timing machine. The "plain" colored distributor springs were
used to allow "all-in" by 2500 rpm. The total advance was correct in
the original weights and limits. There was a spring change in the
vacuum system. Check to make sure your carb vacuum advance port is clear
and functioning on your carb. I replaced the vacuum canister with an
Accell replacement that had an adjustable setting. This allows some
significant advance under no-load conditions, without any "pinging".
Good fortune,
Steve
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Steve Laifman
Editor - TigersUnited.com
Tigerman wrote:
> 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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