I have to ask again, and I believe it's the same question as urban once asked.
what should the distributor (mechanical) advance curve look like?
does anyone have a chart?
2+2 sometimes mentions in spec.

i keep changing and changing, initial timing, springs, and i can get power at some rpm range, but not at full rpm range.

further my mechanical advance kicks in instead of easying itself in.

example: if I use the two medium springs nothing will happen until I rev to 1500 and then suddenly the advance kicks in by 10 degrees and goes up from there. the weights don't stick, so I'm out of ideas I tried a lighter spring, that seems to improve so it kicks at 1200 ...

Anyway if I can't get it sorted at the weekend the Mallory distributor goes in ... Should have done that first day.

Kalli

 

Yeah, the only way to really get this right is on a Sun machine, so you have total control over rpm and vacuum, with extremely accurate advance readings. I have never seen a distributor that was in limits, not "untouched originals", aftermarket, rebuilts are the worst.

Changing the springs usually only makes it worse, unless they are the wrong ones. There should be a primary and secondary, a very thin one and a thick one. The thin one curves lower rpm, and the thick one handles the high rpm. I can think of no reason to use two identical springs.

Modern replacement vacuum advance uses a single adjustment accessable through the hose connector, usually OK, but the OEM advance with spring, spring spacers, and solid limit stop is usually more accurate and still available.

Dunno what distributor you have, but for stock 2V and 4V I usually use the 289 4V setup:



For modified engines I use the BOSS 302 setup. If you don't have a Distributor Vacuum Control Valve, you can just skip the "Vacuum Retard" column.

 

THANKS a million !!!!

i just did what I should have done a long time ago. I disconnected and plugged the vacuum advance at lunchtime. I knew in the back of my head that this caused too far advance but I was blind. Soooo much better now. power is better and driveability increased at the same time. my o my .. what did I do to this poor engine. The plugs are telling the pepper story.

Anyway, I don't have a distributor curving machine (I had one at work back in germany), but at least I know the ballpark.

This is the scariest part:
I have 14 initial and 34 total (max centr advance 20 degrees). max is supposed to be 14 or 11 depending on which chart you use. I'm well off ...

the vacuum advance is 16, not 11. That would explain a lot!

And all the charts suggest what I remembered from setting them up, they should already advance in idle and go up, not start at bl**dy 1500 and then skyrocket

I'll tinker with that tonight. I have to get it right as probably tomorrow I'll get my LM-1 :-]
Thanks for the info with the springs as well!

Kalli