Slant 6 engine ignition timing stays retarded.

[dodgemahal]

I'm tuning the slant in my 1973 Dart. I did all the usual stuff---- plugged the distributor vacuum hose after disconnecting. Set idle at 750 rpm. Adjusted mixture to highest vacuum @ 18" with a rock steady needle.
With the distributor rotated all the way counter-clockwise (confined by the slot), the best I can get is 5 degrees ATDC. It runs like a turd. With the vacuum advance reconnected it runs much better of course, but I can tell something isn't quite right. I've been racking my brains for days but can't solve this. I considered lenghtening the slot. I figured it's time to ask the guys who know way more than I do. Thank you.

 

[Dana67Dart]

the best I can get is 5 degrees

5 deg Atdc is retarded, you want to have it 0 to 5 to 10 Btdc so it's advanced. If you are trying to set it per factory spec (67 dart 273 with CAP calls for 5 Atdc) it will probably run like a turd.

0 = 5 advanced over factory
5 = 10 advanced over factory

I typically run 0 to 5 advanced as the CAP dist has a very aggressive advance curve in the lower RPM and vacuum range.

It is about the same as the non CAP after about 1500 to 2000 rpm

 

[dodgemahal]

5 deg Atdc is retarded, you want to have it 0 to 5 to 10 Btdc so it's advanced. If you are trying to set it per factory spec (67 dart 273 with CAP calls for 5 Atdc) it will probably run like a turd.

0 = 5 advanced over factory
5 = 10 advanced over factory

I typically run 0 to 5 advanced as the CAP dist has a very aggressive advance curve in the lower RPM and vacuum range.

It is about the same as the non CAP after about 1500 to 2000 rpm

I did not explain this very well. Your first paragraph is exactly what I'm looking for. I want 3-5 degrees advanced(BTDC) to begin with. I may modify that later. Factory spec happens to be 0 degrees. The problem is I can't advance the timing past 5 degrees retarded(ATDC) even rotating the distributor as far as it will go. Oh, I can retard it to infinity if I want. That's the issue.
What does CAP mean? Clean air something? How do I know? It did come with OSAC, but I disconnected that.

 

[Dana67Dart]

What is preventing you from rotating the dist?

You should have enough clearance to rotate it 15 deg in either direction

 

[dodgemahal]

What is preventing you from rotating the dist?

You should have enough clearance to rotate it 15 deg in either direction

Because the screw that fastens the distributor down is confined in a metal slot. I've got it as far as it will go. As I said in my original post, I was thinking about lengthening the slot so I can go further. Would you like a picture?
What is CAP?

 

[SIX225]

Might have to pull the distribtor and rotate it one tooth. Also, there is a second adjustment slot on the back side of the distribtor.