dist help
- Thread starter greg
- Start date
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From the tech section (Jim Chenworth)
Here is the real deal on 49 state US distributors from the beginning of time.
All early - 1987 have mechanical advance. Curves vary from year to year.
Early - 1968: Xtra small distributor, vacuum advance (correctly called "non-smog", also sold as "non-USA").
>li>1969 - 1974: XS distributor, but w/ vac retard.
1975 & early 1976: small distributor, completely redesigned, very good quality points distributor. Vacuum retard.
Late 1976 & 1977: Same, but w/ vac advance
1978: redesigned w/ Med. size screwdown, waterproof cap, electronic ignition. Vacuum advance & retard.
1979 - 1980: dual diaphragm advance. One big advance stage for normal operation, small second stage for extra advance at hi-altitude
1981 - 1987 distributor body redesigned to use large cap. Same dual diapragm advance introduced in '79.
1988 - 1992 distributor redesigned w/ out advance. Distributor pickup is a crank angle sensor, advance curve is controlled by computer.
Here is the real deal on 49 state US distributors from the beginning of time.
All early - 1987 have mechanical advance. Curves vary from year to year.
Early - 1968: Xtra small distributor, vacuum advance (correctly called "non-smog", also sold as "non-USA").
>li>1969 - 1974: XS distributor, but w/ vac retard.
1975 & early 1976: small distributor, completely redesigned, very good quality points distributor. Vacuum retard.
Late 1976 & 1977: Same, but w/ vac advance
1978: redesigned w/ Med. size screwdown, waterproof cap, electronic ignition. Vacuum advance & retard.
1979 - 1980: dual diaphragm advance. One big advance stage for normal operation, small second stage for extra advance at hi-altitude
1981 - 1987 distributor body redesigned to use large cap. Same dual diapragm advance introduced in '79.
1988 - 1992 distributor redesigned w/ out advance. Distributor pickup is a crank angle sensor, advance curve is controlled by computer.
Just to be sure, look at the vacuum diaphragm on the side of the distributor. It has a crimp around the middle. Is the vacuum port on the distributor-side of the crimp (vacuum retard) or on the opposite side of the crimp (vacuum advance)?
Landpimp said:
Yep. Distributor side of the diaphragm crimp (towards firewall) is retard. Opposite side of the crimp from the distributor (towards radiator) is advance.
Put some suck on the diaphragm fitting and watch the contact plate inside the distributor. Advance rotates the plate CCW. Retard rotates the plate CW.