Good morning all,

I was curious what the total timing (or "all in" timing) should be on my '66 Toronado's V8 but I can't seem to find this spec in the manual anywhere. Am I just missing it? The best I can find is in the distributor test specs which says it should be 8-10 degrees mechanical advance at 2100 RPM. That's not really telling me what the total timing should be on this engine though so I'm not sure what it should be. Stock, original engine, no modifications.

Thanks!

 

Including vacuum advance?

 

With the vac adv disconnected, use a dialback timing light, measure the idle speed timing (initial) and then measure at what rpm and the timing advance amount stops (total), note that timing. Subtract the initial from the total and it will give you how much mechanical advance is built into your distributor.

 

Yeah, okay I get that but what are you measuring against? How would I know if what I measure is within spec? I mean, this car is bone stock and never messed with so it shouldn't be out of wack but I'm just trying to learn more about the engine.

 

You disconnect the vacuum advance when checking this correct? So I guess no? Vacuum advance goes away at high RPM right?

 

SOP is to disconnect and plug vacuum advance for consistency, but people do measure it connected -- usually comes in ~ 50° altogether. Disconnected, with only static + mechanical, a good range is 32-36° depending on variables like cylinder pressure and gas quality. Most people like to get max advance in around 3K or just before.

 

You will likely get 100 different answers. I found the following to work well for most mid-60s - mid-70s stock or lightly warmed-up Olds engines

The distributor includes vacuum and mechanical advance...read on...Short answer 36-38°

The long:
Before doing anything obtain a vacuum gauge and set back timing light.
Verify the ignition & fuel systems are in good shape, and dwell is 30°.
Verify zero vacuum leaks present.
Put in the gas you will normally drive with.

Hook up the vacuum gauge to an intake vacuum source, (not a ported source).
Adjust the carb to achieve the highest possible vac reading.
Next, rotate the distributor to obtain the same high(est) vacuum signal.
Go back and forth between these two to get that "highest" vacuum reading.

Tighten the distributor and road test. You could be satisfied without going any further.

Basic rule is to give the engine as much timing advance as possible without detonation( spark knock).
You may need to back off on real hot humid days if it starts to detonate. Put some octane booster in at every fill unless you can source pump gas 92-94 Octane non-ethanol gas.
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Granular details for today's gas and a little extra performance:

-Start with 12-14° base timing with vac canister plugged off, warm curb idle at 650-750rpm.
-Plug the vacuum canister into a direct manifold vacuum source. You want it to advance another 8-10° at curb idle (adjustable travel (not rate) canisters are recommended and readily available).
The centrifugal advance should bring the rest or total timing before 2800-3000rpm at ~36-38°.

Verify the centrifugal weights and springs are clean and lightly lubricated.
Base ~13+9° = ~22° at idle. Centrifugal total is ~14-16° = grand total of ~36-38°

Centrifugal should hand off the vacuum canister timing smoothly as the engine vacuum drops and the throttle plate opens. Beginning at ~800-1000-1200rpm.
The best way to achieve this optimal curve is to have someone put the distributor on a SUN dist machine and tune it for you.
But if you pay attention to the details using a vac gauge and set back timing light you can get real close.
You can change up the weights, springs, and stops. You can use two different weights of springs. They do not necessarily need to be a matched set to achieve the goal.

 

Dang! Where else are you gonna get such nicely presented answers to such questions? Thanks fellers, you guys are awesome!

 

I thought you understood the distributor numbers in the manual with my response. Getting back to this, what the manual is telling you is that at 4200 Rpm you should have 16-20* of mechanical advance at the crank built into the distributor. The numbers referred to in the manual are in distributor degrees, the distributor turns 1/2 the speed of the crank. Your ignition timing settings are in crank degrees, so add whatever the initial timing you set at idle to the total and you have the total timing for the engine. For example if you set your initial timing at 12* btdc, without vthe 16ac advance at 4200 Rpm you would add 12 + the 16 to 20 of mechanical advance for a total of 28 to 32 degrees.