Mustang Forum

Technical & General Discussion Area => Tech Torque Pre 1973 => Topic started by: pmb0186 on November 16, 2020, 12:01:18 PM

Title: Ignition timing total advance
Post by: pmb0186 on November 16, 2020, 12:01:18 PM
Has anyone played with their distributors total mechanical advance?
Mine has always pinged only in hot weather and something I've never got around to sorting.
If I wind the timing back anymore (retard) it runs poorly so not an option, so the answer is reduce the total advance.
I understand I'm going to find the attached inside and it can be turned around to reduce or increase total timing.
Has anyone done this ?
Did it work?
 
Title: Re: Ignition timing total advance
Post by: HEVEN67 on November 16, 2020, 12:12:49 PM
do you know how much total advance you have?
Title: Re: Ignition timing total advance
Post by: pmb0186 on November 16, 2020, 12:21:24 PM
I will find out tonight
Title: Re: Ignition timing total advance
Post by: GEOFF289 on November 16, 2020, 12:36:14 PM
What distributor is it?

I have done exactly what you describe with my MSD Pro Billet dissy. It came with various "spacers" I guess you'd call them that can be changed to limit the mechanical advance. Also different springs to control how early the mechanical comes in.

My GT40P heads don't like a lot of total and I found that even the lowest total these spacers provided was still too high with the initial where I wanted it to be. I found some aftermarket aluminium ones (standard MSD are plastic) that gave me some better options and I have one in it now that keeps the total to a level that works while allowing 14 degrees of initial which the car seems happy with.
Title: Re: Ignition timing total advance
Post by: jiffy on November 16, 2020, 07:49:02 PM
as a quick and dirty fix, you can try bending out the little tabs the springs anchor on to increase the spring pressure restricting the advance.
It won't change the total advance but it may move it later in the rev range which isn't going to suffer the pinging under load.
Title: Re: Ignition timing total advance
Post by: pmb0186 on November 17, 2020, 11:08:05 AM
Last night found something I didn't expect, someone has tried to sort this in the past.
It is already on the lower advance 10L and a restrictor added see below.
Initial timing is 5 DBTC and with the 10L add another 20 makes 25 total no much.
So as jiffy stated I bent the tab on the heavier spring out just a tad, it sees a bit better but need a hot day to be sure.
I have seen a on the web this restrictor before has any seen this on there car?
Title: Re: Ignition timing total advance
Post by: GEOFF289 on November 17, 2020, 12:50:54 PM
I think you need a better solution than that. 5 initial is way short of optimum and it should be able to cope with more than 25 total in any conditions.

I've got 14 initial and 16 mechanical for a total of 30 which is as much as my heads seem to like.
Title: Re: Ignition timing total advance
Post by: barnett468 on November 20, 2020, 04:19:33 PM
Has anyone played with their distributors total mechanical advance?

Yes, I have modified countless distributors.


Mine has always pinged only in hot weather and something I've never got around to sorting.

This may not be due solely to to too much advance.

What is your compression?

What grade gas are you using?

What is the engine temp?

Is the engine temp higher now than when the outdoor temp is cooler and it does not pink?


If I wind the timing back anymore (retard) it runs poorly so not an option, so the answer is reduce the total advance.

Do you have a vacuum advance that is functional?

If so, try driving with it disconnected.
Title: Re: Ignition timing total advance
Post by: pmb0186 on November 25, 2020, 03:38:55 PM
To answer you questions
No idea of compression
running 98
cold 160 thermostat
pings in hot weather only and engine as a result runs hotter about half range on gauge
Title: Re: Ignition timing total advance
Post by: pmb0186 on November 25, 2020, 03:42:55 PM
another thing, have a set of colder plugs to go in AP6FS see what happens 
Title: Re: Ignition timing total advance
Post by: barnett468 on December 01, 2020, 12:04:43 PM
To answer you questions
No idea of compression
running 98
cold 160 thermostat
pings in hot weather only and engine as a result runs hotter about half range on gauge

1. you have the wrong thermostat

2. how hot does the engine get on the highway?

3. how hot does it get while idling for a light?

4. what is the outdoor temp while driving?