Total mechanical advance on Mopar smallblocks is usually recommended top be 35 degrees. However, without opening up your distributor to see what givernor is in there, I don't know what your base timing should be. The governor has stamped on it the number of crankshaft degrees of advance it provides. But stock governors provide everything from 16 to 30 degrees of mechanical advance.
I would leave it at 10 BTDC and listen for ping. Back it off in 2 degree increments if you hear it knocking.
Depending on the emissions package and application, factory Mopar timing in the 70s and 80s was eveyrthing from 5 ATDC (yes, after TDC) to 16 BTDC. The remanufacture distributors have whatever parts were floating around the assembly line, not the original calibrated parts.
It went in the trash on Saturday and Monday was trash pick up. Sorry! Did you go to the Rat Patrol season opener car show? That’s where I was headed with a Few of my van friends but I couldn’t make it.
Bummer! No worries. My job keeps me pretty busy. I don't ever go to car shows. Between my job, home maintenance, and repairing all the cars in my extened family, I am lucky to get any free time for fun projects.
Windows- they're what make a van worth owning!
Re: 360 Timing with Smog
#748773 May 22nd 2019 7:50 pmMay 22nd 2019 7:50 pm
Thank you sir! I really appreciate all the helpful info you provide here. My thought is if I plug the vacuum as described, set the base to 10 btdc at idle and then rev the engine to 2000-2500 rpm, I should be getting full mechanical advance to whatever it’s governed and would subtract the base timing to have that number. I can adjust the base idle accordingly if it’s over 35 degrees. I’m hoping atleast that if they are selling these dizzys, then they’d be set up so that they should work with a fairly factory base timing setting.
That sounds right, except some Doddge distributors don't have the timing all in until 3000-3500 RPM. But running it up to 2500 should be close enough.
Aftermarket distributor remanufacturers throw them together with whatever is laying around. No telling what your advance curve is.
You should take the time to map out the curve while you are measuring total mechanical advance. Advance the RPM in 100 RPM increments and note the timing. It might be easier to sent your base timing to TDC when you start this test.