Distributor Question
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Distributor Question
When installing a new vac advance unit on my points tach drive distributor, a small D shaped plate fell out. I didn't notice it before disassembly. (DUHH) It has notches in it and I assume it's a vac advance limit/adjustment. How does it mount and what does it do????
Thanks Guys
Eddie
Thanks Guys
Eddie
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Distributor Question (Silvr77)
You must have had an adj vac adv unit installed, it goes under the drivers side bolt for the vac adv can but it may not work with your new can. I believe each notch is 2 degrees, at least it is for the cran unit I installed. I could not fit the plate in my MSD dist so I made my own plate out of sheet metal and had to alter the Crane unit a little to make it fit.
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Re: Distributor Question (Fevre)
This distributor came on my 72, but the ID band has a '76 date code. It's obviously not a Vette distrib cause it has points. The plate will work cause the new vac is identical. OK...each notch is approx 2 degrees of advance. Does adjusting this plate allow for a higher total degree of advance...or does it make the vac advance start at higher RPM's?? Please explain???
Eddie
[Modified by Silvr77, 7:36 AM 3/2/2004]
Eddie
[Modified by Silvr77, 7:36 AM 3/2/2004]
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Distributor Question (Silvr77)
I do not think think they came stock with the limiting plate. This plate will only limit the total adv and it does this by adv your base timing by the same amount as the limit, so it is one for one, if you limit it by one notch (2 degrees) then you need to decrease you intitial timing by 2 degress to keep your same total initial+mech adv, if you do not back your initial timing off then you will be running higher adv at WOT which can cause detonation. If you did not buy an adjustable vac adv can then you cannot adj the rate at which the vac adv comes, the crane unit I have has that ability. With the crane unit there is a long allen head wrench to inserts into the vac port and you can adj the rate at which the vac comes in.
My suggestion is to follow Lars' tech paper on how to set up you timing curve without using the plate and then see if you have any problems. You might not even need to limit your vac adv at all. Again remember if you use the plate and pull adv out of the vacuum adv side you will need to pull adv on the initial side to maintain you WOT (initial+mech) adv setting.
My suggestion is to follow Lars' tech paper on how to set up you timing curve without using the plate and then see if you have any problems. You might not even need to limit your vac adv at all. Again remember if you use the plate and pull adv out of the vacuum adv side you will need to pull adv on the initial side to maintain you WOT (initial+mech) adv setting.
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Re: Distributor Question (Fevre)
If you did not buy an adjustable vac adv can then you cannot adj the rate at which the vac adv comes, the crane unit I have has that ability. With the crane unit there is a long allen head wrench to inserts into the vac port and you can adj the rate at which the vac comes in..
Eddie
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