DUI Distributor cap indexing (1 Viewer)

[steffan]

I had another thread going about not being able to get my new engine running properly, this is the follow up.

The short of it was that I just started my new engine - was able to get it to fire up, get the idle mixture decent, idle speed adjusted and timing set. The problem was that it would break up, stumble and lean out anything over 1200 rpm. No vacuum leaks found etc. When I disconnected the vacuum advance it would run up and down perfectly.

That narrowed it down to the distributor so I searched up and down trying to find similar issues but no luck.

I ended up calling the company and much to my surprise I was able to speak to a live person on the second ring.
Apparently, some of these distributors have 2x different cap positions which indexes the timing just enough to through the advance completely off. I'm not sure why this isn't addressed in the instructions - couldn't find a mention of it anywhere even in other forums etc

Pictures of the cap for reference with the tab to locate it in the housing

 

[steffan]

here are pictures of the distributor and the 2 notches: one at 11 o'clock and one at 1 o'clock - of course, I chose incorrectly
Simple enough to move the cap but that means pulling the spark plugs, resetting the timing etc etc
Hopefully this saves someone the headache

 

[pb4ugo]

Glad you figured it out. You should add this response to your original thread so that thread comes to a conclusion.

 

[jestlurnin]

I used a sharpie to mark the cap and the base of the dizzy so next time I have the cap off I don’t run into this situation.

Thanks for the post. This will 100% help someone down the road.

 

[tlc762]

Which position is the correct one to use?


Asking for a friend...

 

[steffan]

Which position is the correct one to use?


Asking for a friend...

In this picture, it’s the notch on the top right - the one closest to the wire leads