Chrysler 440 ignition timing.

In '72 it was 10=B0 BTDC, vacuum advance hose disconnected from distributor and plugged. '73 probably not too much different.

10 degrees before DTC with the automatic (All interceptors were automatics IIRC) and I think the standards were the same. In 74 the standard 4bbl went to 5 degrees, and the Magnum to 2.5

The book may say 10 BTDC, but is that what he wants if he's going to be using the relatively low octane gas available today? He may have to back it off to zero BTDC if he wants it to run cool (and not ping).

What if he wants (or has to) pass an emissions test? On pump gas?

I've always set my timing at what-ever setting gave the best vacuum at idle.

Is this mechanical points/condensor, or electronic ignition?

As others have already said 10 is the correct number. Compression was dropped enough by '73 that it will run fine on regular unleaded or mid grade at worst. My '73 Imperial ran on regular unleaded even in the FL heat without ever pinging.

Steve B.

There were a number of different distributors used over the years, and I don't know exactly which one you have. In any case the TOTAL timing (all mechanical advance IN, no vacuum advance) on a Mopar big-block should be around 35-38 degrees. Usually that means a "base" timing of 10-12 degrees BTDC at idle with the vacuum advance plugged, but some of the late "smogger" distributors had a ridiculously long advance curve that required you to set the base timing at 0 degrees. (Yuck!).

Basically, if you can't find the exact spec, either set it by total timing and let idle fall where it may, OR try it at 10-12 BTDC and back off if you get pinging under WOT acceleration.

Fuels have changed so much over the years (and the odds are so good that the distributor or other engine components have changed) that tuning to where it runs best is often the best way to go anyhow.

In news: snipped-for-privacy@Man.com, MoPar Man decided to enlighten our sheltered souls with a rant as follows

Electronic ignition, standard set up I think...

Thanks to everyone for the info, I'll have a look at it at the weekend..