Time for the typical newbie timing question....

[Steve-o]

So after installing the rebuilt distributor I got from @halifaxhops (gorgeous work btw) and setting the timing by ear so it ran smooth enough to get the timing light on, I realize I dont know what I'm looking for on the pulley as a reference mark. I have the piece on the block with the marks on it and the hole (which I read is TDC) so when I put the light on there I dont see any marks on the pulley at all. Granted it's dirty/rusty. What sort of mark am I looking for? A notch? A line? A dot?

Timing is 38° or so with vacuum attached at full advance, correct?

I did a lot of looking online before posting this and found most of the info I found actually on this forum but not a pic of what it is I'm supposed to be seeing.

I will say that the 2 volume service manual is pretty worthless when it comes to this....

 

[Polara_500]

Should be a groove front to back on the damper.

 

[saylor]

try not to die -

- saylor

 

[Steve-o]

Perfect thanks!! that's exactly what I needed to see!
The 38 degrees is what I'm aiming for more or less?

 

[Polara_500]

View attachment 416852

try not to die -

- saylor

That's the pic I don't have, nice clean shot.

 

[Davea Lux]

You can make the grove easier to see with the timing light if you scribe it with a piece of white chalk.

Dave

 

[carfreak6970]

Perfect thanks!! that's exactly what I needed to see!
The 38 degrees is what I'm aiming for more or less?

kind of, but not quite. since I am not to sure what engine you have in your vehicle, I would assume 38 degrees is your Total timing ( that would be your initial plus your mechanical advance). That vacuum advance provides additional timing at steady state cruise (where the engine is pulling higher vacuum) and most the time does not get account for when talking about total advance. Your initial timing is something you will set. The mechanical advance is set by the internals of the distributor. the vacuum advance is set by that vacuum pod.

What you want to do is set your initial timing. Your initial timing will be much lower than 38 degrees. Without knowing your engine or drive-tran combination, it is hard to guess what you should aim for. But on a mostly stock 70 polara with a 440, I have that sent between 10-12 degrees initial.

edit*

to set your initial timing, find top dead center on the number 1 cylinder. when the piston is at the top of its stroke (right after it compresses the fuel in the 4 stroke cycle). you line the distributor and cap up with with the #1 plug wire and that should be close to 0 degrees initial. That would be enough to get the engine started. Once the engine is running and at operating temperature, unplug the vacuum advance and plug it. Then you can set your initial timing to what ever you find to be best.
(dont know your experience with these types of vehicles, which is why I tried to break it down a bit)

 

[saylor]

if you got a big block make yours look like mine and you will be close thats about 9BTDC and it spins towards the 0


try not to die -

- saylor

 

[67Monaco500]

I run my 440 with 12 initial but only 34-35 total. I have also had several 340's and have never put more than 36 total. My feeling is that 38 total may be a little risky in the long term but I am no expert. I am very curious in what others say.

 

[70bigblockdodge]

35-36° total is about right for a big block.
32-34° total is about right for a small block.
Total is initial plus mechanical/centrifugal. Average Chrysler distributor has about 20-22 degrees advance movement in it. This is where the 12-14° initial/idle. At no point in the setting process should the vacuum advance be connected. You are setting for safe/ performance at idle and wide open throttle. The vacuum advance comes into play at cruise. Since cylinder filling is low at cruise you need to lite the fire earlier to completely burn the charge resulting in clean burning, no oil contamination, and better fuel economy, a win win.
To set total timing you need to rev the engine up to when the timing mark stops advancing then twist the distributor to set it at above listings for your engine family.

 

[1970FuryConv]

Timing is 38° or so with vacuum attached at full advance, correct?
....

Steve, I agree with Dave. Total Timing should be around 33-35° WITHOUT VACUUM ADVANCE. Once you add in vacuum advance, total timing should be more like 50-55°.

 

[Steve-o]

All great info thanks!
So the missing details....
383 with a 2 barrel Holley and a freshly rebuilt stock distributor for that engine. Auto trans.

I stuck the timing light on it and my numbers were way off. The 10-12 at idle seemed normal to me and something around 20° advance out of the distributor seemed normal too (based on my other car experience)
There seems to be so much speculation about vacuum hose on/off and numbers.

So to understand...at NO POINT while timing the engine should the vacuum be connected, correct? Seems conflicting info even within this thread.

Correct me if I'm wrong please, because this is how I learn, but the vacuum advance is for the "off idle" advance correct? Just until the centrifugal kicks in?

I have the rest of the week off (it's about time) so I have all sorts of time to play with it now.

 

[Polara_500]

Base timing (at idle) is set with vacuum disconnected and capped. If you're getting into setting full advance at rpm then you'll want vacuum.

 

[saylor]

cap all the carb holes and cap the vaccuum pot on the distributor with the little rubber nubbers from vatozone. get the car where it will run in the driveway. drive it around the block and take a wrench with you for the dist hold down bolt. dont get into it hard, but accellerate at some pace. if it pings at all, get off the gas. pull over and adjust the dist until it quits pinging. you only have to move it a smidge it turns 2:1 to the motor. get it running with no ping, then go hook up that vac line to the can.

the can should have a what 7/32 or so allen head inside right down the pookey hole, i forget which way is which, i want to say turn it full clockwise to start, but go read that somewhere.

try not to die -

- saylor

 

[70bigblockdodge]

No vacuum advance when setting distributor.
Vacuum advance comes into play at cruise rpm (on a Chrysler product) GM does it differently (they port vacuum advance to manifold vacuum, I would assume because they use a wider mechanical swing, this can lead to a unstable idle, and why Chrysler does not do it).
As long as you are not getting surging at highway rpm and it's not pinging at light throttle cruise, vacuum advance is probably okay. General ball park figure is between 45° and 55° btdc at ~3500 rpm. This is basically everything added together initial 12-14 + total mechanical 20-22 + vacuum advance 10-20°.
If you read in the FSM the degrees they give are distributor degrees (1/2 crank degrees) or double their numbers and it will give you the crank degrees. They do it like this with the thought that you will be checking the distributor on a distributor machine. I'm going to guess you don't have one of those, or you wouldn't be asking these questions.
So not correct vacuum problems by turning distributor or you will have to start over. The vacuum advance is a whole different animal. If you get mechanical side right and want to fine tune vacuum advance. Let us know after you get mechanical straight.

 

[1970FuryConv]

So to understand...at NO POINT while timing the engine should the vacuum be connected, correct? Seems conflicting info even within this thread.

Correct me if I'm wrong please, because this is how I learn, but the vacuum advance is for the "off idle" advance correct? Just until the centrifugal kicks in?

Hi Steve,
My answers and advice on timing.

1. Correct: Vacuum advance is for off idle advance. It comes into play when you are at a steady "cruising speed".
2. For this reason, when you do connect distributor vacuum hose, it is connected to ported advance, which is above the throttle plates rather than manifold vacuum advance, which is below the throttle plates and would affect idle timing.
3. You set idle timing with vacuum advance disconnected from the distributor.
4. You then set total timing with vacuum advance still disconnected. You need to have a dial back timing light or an aftermarket harmonic balancer with gradients up to 60° BTDC. Then set total timing to 33-34° at around 3000 rpm
5. You finally connect the vacuum hose and hope that cruise timing is 50-55°BTDC. IOW, connecting the distributor vacuum should add another 15-20° advance at 3000 rpm. If not, using an 3/32 allen wrench inserted into the vacuum canister, adjust. Turning the allen wrench clockwise decreases cruise vacuum advance, turning counterclockwise increases. Reconnect vacuum hose and see if you are in the 50-55° range. If not, keep adjusting and checking.
6. Road test and check for knocking at WOT and cruise. If knock occurs at WOT, disconnect vacuum advance and retard timing 2 or 3 degrees and see if problem goes away. If WOT is OK, but you have knock at cruise, insert allen wrench into distributor vacuum canister and turn clockwise a little to decrease vacuum advance 2-3°. Keep road testing and adjusting until you have no knock. Objective: max power with no knock at WOT or cruise.
7. Note: every motor is different, the steps above are a starting point. From there, you can experiment with timing as much as you want until you get what you want. Best of Luck, Ben

 

[Steve-o]

Perfect! this is EXACTLY all the info I needed. I have a timing light with advance function and tach so that's why I was asking what full advance should be. I guess my thought is I'm not driving around at idle and because my background is mostly air cooled engines, full advance timing is critical....where as here it is more of a play by ear it seems.

The distributor was rebuilt by halifaxhops and was run and tuned on a Sun distributor machine before sending to me.
I really shouldn't have to mess with the vacuum pod I hope. I'll play with it tomorrow and report back.
Thanks!

 

[1970FuryConv]

I guess my thought is I'm not driving around at idle and because my background is mostly air cooled engines, full advance timing is critical....where as here it is more of a play by ear it seems. Thanks!

Air cooled. Hmm, what air cooled engine? So did you switch from a Volkswagen Beetle to Mopar? Or maybe from a Corvair?

 

[HWYCRZR]

@Steve-o
Are using the manual to determine at what rpm each of your advance readings should be? First if @halifaxhops already did your advance curve you only need to worry about idle timing. If your idle is set close to factory (I didn’t see what year or engine you had). Your idle timing should be around 7-1/2 - 12 degrees Btdc. You should only see the full advance at high engine rpm. With vacuum advance disconnected and vacuum hose plugged. I run my ‘68 383 2bbl right at 7-1/2. I run 91 octane non ethanol, and idles perfectly. Some 4 bbl’s are around 10 degrees. Set it per engine spec and take it for a drive.

If you want to check your vacuum advance canister after you set base timing you can do that with a hand vacuum pump connected to your vacuum advance while the engine is idling. If you start start pumping it up you will see timing start to advance around 8-10 inches hg, (spec on my car- yours may be different in your service manual) if it cracks open a little late you may feel a hesitation between idle and mid range acceleration. I noticed a difference with as little as 3 inches of vacuum change to crack open the vacuum advance. But then again I am very anal and striving for factory perfection.
Your distributor advance as shown in the manual is 1/2 of what your timing light will read. 5 degrees distributor advance is 10 degrees measured at your flywheel with the timing light.

If you want further explanation snap this picture in your service manual and I can help translate.

 

[halifaxhops]

Hi Steve,
My answers and advice on timing.

1. Correct: Vacuum advance is for off idle advance. It comes into play when you are at a steady "cruising speed".
2. For this reason, when you do connect distributor vacuum hose, it is connected to ported advance, which is above the throttle plates rather than manifold vacuum advance, which is below the throttle plates and would affect idle timing.
3. You set idle timing with vacuum advance disconnected from the distributor.
4. You then set total timing with vacuum advance still disconnected. You need to have a dial back timing light or an aftermarket harmonic balancer with gradients up to 60° BTDC. Then set total timing to 33-34° at around 3000 rpm
5. You finally connect the vacuum hose and hope that cruise timing is 50-55°BTDC. IOW, connecting the distributor vacuum should add another 15-20° advance at 3000 rpm. If not, using an 3/32 allen wrench inserted into the vacuum canister, adjust. Turning the allen wrench clockwise decreases cruise vacuum advance, turning counterclockwise increases. Reconnect vacuum hose and see if you are in the 50-55° range. If not, keep adjusting and checking.
6. Road test and check for knocking at WOT and cruise. If knock occurs at WOT, disconnect vacuum advance and retard timing 2 or 3 degrees and see if problem goes away. If WOT is OK, but you have knock at cruise, insert allen wrench into distributor vacuum canister and turn clockwise a little to decrease vacuum advance 2-3°. Keep road testing and adjusting until you have no knock. Objective: max power with no knock at WOT or cruise.
7. Note: every motor is different, the steps above are a starting point. From there, you can experiment with timing as much as you want until you get what you want. Best of Luck, Ben

Nice explanation. Steve if you have a issue Still call me I will walk you through it. Only issue I see is the vacuum advance adjustment it does not adjust the actual timing it adjusts the rate of timming. Lot of confusion on this. Here is a cut away pic shows it way better.