cjlandry
Jan 14th, 04, 1:49 PM
After about 30,000 miles, my modified HEI advance mechanism quit working. It was a gradual thing, apparently occurring over the last month. My fuel economy kept going down and I couldn't figure out why.
When I went to replace the cap and rotor, I noticed that the mechanical advance bushings were worn and the mechanism was holding it advanced. I hit it with a timing light with the vac advance connected and disconnected and nothing changed. I figured I had a busted diaphragm in the vacuum advance.
Since I've been running 22-degrees initial for a while anyway, I decided to try the aftermarket kit again (which only gives about 15 degrees of added advance).
O'Reilly had the Mr. Gasket kit on hand, so I got it. I figured if I didn't like the way it works, I'd just use the bushings out of the kit and keep my modified OEM HEI weights and center plate.
Well, the Mr. Gasket kit actually has a picture showing how to install the thing. It's opposite of how I've done them in the past (the center plate was upside-down). Someone here (I don't remember who) told me I was doing it wrong, but I didn't listen, and it didn't seem like it would work that way when I tried it on a distributor shaft assembly. If you read this, feel free to say, "I Told You So!"
Anyway, it works fine like that. Just gotta run extra initial for it to work. And my vacuum advance is back in the picture, giving me over 50-degrees under cruise conditions just like it's supposed to.
And the Mr. Gasket instructions also give a GM part number for a vacuum advance canister that won't give any advance at anything under 10" of vacuum. The part number they supply is 1973511.
So my badmouthing of the aftermarket advance kits is over. It's not perfect, but it works for now.
When I went to replace the cap and rotor, I noticed that the mechanical advance bushings were worn and the mechanism was holding it advanced. I hit it with a timing light with the vac advance connected and disconnected and nothing changed. I figured I had a busted diaphragm in the vacuum advance.
Since I've been running 22-degrees initial for a while anyway, I decided to try the aftermarket kit again (which only gives about 15 degrees of added advance).
O'Reilly had the Mr. Gasket kit on hand, so I got it. I figured if I didn't like the way it works, I'd just use the bushings out of the kit and keep my modified OEM HEI weights and center plate.
Well, the Mr. Gasket kit actually has a picture showing how to install the thing. It's opposite of how I've done them in the past (the center plate was upside-down). Someone here (I don't remember who) told me I was doing it wrong, but I didn't listen, and it didn't seem like it would work that way when I tried it on a distributor shaft assembly. If you read this, feel free to say, "I Told You So!"
Anyway, it works fine like that. Just gotta run extra initial for it to work. And my vacuum advance is back in the picture, giving me over 50-degrees under cruise conditions just like it's supposed to.
And the Mr. Gasket instructions also give a GM part number for a vacuum advance canister that won't give any advance at anything under 10" of vacuum. The part number they supply is 1973511.
So my badmouthing of the aftermarket advance kits is over. It's not perfect, but it works for now.