A12 Timing Specs

Does anyone know the factory timing specs for a stock rebuilt A12 4 speed Road Runner? Thank you

I don't recall the stock timing spec off the top of my head but it doesn't matter because your sixpack will hate it. Try the stock timing if you must but it will probably like 16 to 20 initial and about 36 total a lot better.

Not saying this is A12 440 3x2 specs, but I've had this for a long, long time and may get you close or at least a good starting point.

MikeR

From my memory,???I'm thinking 12* BTDC. w/727
Mind you this is 51 years ago.

When I put headers and cam and a few other mods, I ran 20* initial, no vacuum
advance (old thinking) and 40* total.

The starter had to grunt a bit in hot weather.

Joe

PS As an aside, pure stock, with bumped timing, it ran 13.60s 106 MPH
With the mods, on OE Polyglas, 12.8s at 112 MPH

A lot of fun in those days!!

I agree. This is not 1969 where you can buy good gas. The gas makes the difference.

While I agree with the recommendations here, I am not sure that the OP should start throwing 36* to 40* at his 440 with the limited experience that he appears to have.

With that caution, the only other thing I would add is that he get some help and re-curve it to have it all in by 2,000RPM or so.

Correct, Sunoco 260 then, I think 103 or 106 Octane.

Joe

Yikes, TDC at idle. That distributor will definitely need recurved. The curve described in that FSM is asking for the idle speed, vacuum and timing to circle the drain (aka death spiral). As the vacuum drops the idle speed drops, as the idle speed drops the timing drops. As the timing drops the idle speed and vacuum drop even more and so on until the engine stops running.

I've probably owned at least 15 BB Mopars '67-'70, and every one of them liked 10 degrees or more initial timing.
Most had FSM specs of 0-4 degrees.
They typically didn't like more than about 36 total mechanical, though with the vac advance connected they of course see more under certain conditions.

I just finished up a 68 440 Hp with the same pistons and heads as your 69. He had trouble with a stumble and pinging ever since the car was done and he was never able to get it right. I worked on the carb and realized it was more to it than carb problems. I got an FBO distributor and ignition. It has a 16 degree initial timing with 34 total now. I have to run 93 octane with booster to get it at that. Iron heads don’t help. I’m not sure if the exact CR but it’s not much over 9:1. It now has 12-14 inches of vacuum and runs better than it ever has. No stubble or clatter.

Really had nothing to do with gas in the day, versus now. Though it is different. That was CAP, Clean Air emission standard. Chrysler's method for improving idle emissions. Leaned out idle and low speed carb jetting, and less initial timing to burn product in a hotter exhaust; and sometimes higher idle, hence a solenoid on some models.

So for a complete answer is this the original distributor? If so the mechanical advance is much more then the earlier cars. 30deg total for manual according to the spec. You can certainly add more initial and still keep total in the 34-36 range depending on how your motor likes it. But make sure you know how your carb was set up too.

If you want to go performance oriented, then your going to need more initial, but your recurve really means a new cam stop with less mechanical advance... or welding up the slot on the current one if original. If you don't and lets say you go to 12 or so. You will be advancing way too much and wind up with 42 total at minimum and that is with no vacuum advance. Pushing you into detonation range.