Installing distributor question

[MN_Stang]

I saw a youtube video where a guy working on a 5.0 had problems because he said he installed the distributor "one tooth off." He had TDC and the rotor was on one, but it ran very choppy until he said he solved getting it on the "right tooth" by rotating the whole distributor a bit.

I thought as long as you had it TDC and the rotor was exactly on #1, which tooth you were on wouldn't matter?

I'm just about to install a new distributor and now I don't know if I need to alter my plan. I originally thought TDC and rotor pointing #1 was all I had to concern myself with before setting advance.

Bonus question...I have an Edelbrock high rise intake, higher performance cam and four barrel vs stock. Am I still looking at advance timing of 10-14 initial / 34-36 total?

Appreciate any help! This is my first time installing a distributor / timing.

[wraithracing]

Disconnect coil wire from coil. Remove the spark plug on #1 cylinder. Bring the engine up to TDC on the compression stroke on cylinder #1. Remove Distributor cap and verify that rotor is point at #1 cylinder. If everything checks out remove distributor. When you remove it the distributor will rotate slightly due to the cut of the gear. Note the approximate amount of rotation. To install the new distributor set it at about the final point when you removed the first distributor, then slowly lower into engine. Keep in mind you have to match up the alignment for the oil pump drive and the #1 cylinder so if the distributor doesn't align properly or doesn't fully seat properly it can be the oil pump drive. You also want to make sure that if you have the vacuum advance canister that there is enough room for timing adjustments after install. Remove and adjust oil pump drive and/or distributor alignment until everything is right and fully seated. Install the hold down and tighten finger tight. Start engine and using a timing light adjust as needed for your timing preference.

Initial timing of 10-14 Degrees should be fine. How the engine runs and starts will tell you if you need more timing or have too much. Good Luck!

[Walking-Tall]

I've found it best, and quickest to immediate up and running, is to yes find TDC of #1's compression stroke (both valves closed), and to stab the distributor in and aligned to the #1 distributor post, but at the initial timing you want to run... 10, 12, 14, etc... so, moving the crankshaft does mean fiddling with the oil pump driveshaft... or, the old man showed me years ago... if you're certain that the distributor is headed in exactly where you want it to, and it won't go in that last bit (not engaging with oil pump drive shaft), bump the starter a time or two and it'll drop right in (the helical gears are always pulling the distributor downward)...

On your question about initial timing setting... it depends on your vehicle combination and the octane gasoline that's in it... an initial timing setting of as much as it will stand prior to pinging is best. How much "higher performance cam"? Specifically, how much intake duration @ 0.050"?
I've got a 218-degree in mine (only ever needs 87-octane, with 9:1, ported E7TE's, RPM intake, etc), and run 18-degrees initial and 38-degrees total (limited centrifugal/mechanical advance to 10-degrees in the distributor, so 20-degrees at the crankshaft once "all in") at about 5500rpm... and a vacuum advance that only adds 12-degrees (crankshaft), connected to full manifold vacuum... snappy response and pulls like the proverbial freight train, runs like a champ.

Hot tip for folks with a warmed up Ford and re-curved DuraSpark II distributor... the vacuum advance mentioned above is originally for on 1974 Ford F250's with 390 engine...
Got mine at RockAuto... STANDARD MOTOR PRODUCTS part # VC230...
If you view the pictures, you'll see a "6" stamped on the stem that enters the distributor... that means it'll add only 12 crankshaft degrees... which is very beneficial for at idle and cruise with a hotrod's increased initial timing amounts and faster advance curves...

[MN_Stang]

Thanks a lot to both of you for the replies! Love this community!

[Hans]

O man, that's great info about the vacuum advance.
I bought the adjustable one, but can't get it lower then 19 degrees (from 24). Way too much still.
Thanks Walking Tall!


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[BMW Rider]

The rotor position is good so far as indicating that you are in the ballpark with the distributor but is never going to get you close on the initial timing. Having the distributor off by a tooth can be overcome often by turning it to where it needs to be but can run into issues with the wires not fitting properly. Best to get it in the right spot.

As for setting the initial timing prior to starting the engine, don't go by the rotor position, line up the tooth of the pickup coil or hall effect switch on later models. That is what actually triggers the spark. The rotor timing is actually a little off to account for its movement as the spark current is created and travels through the wires to the rotor to jump the gap. In lining up the pickup coil teeth you should be able to come within a couple of degrees of your desired initial timing if you set the crank position to the desired timing point instead of exactly at TDC. Now for real old school, you would do this by setting the distributor where the points first open.

[dynodon64]

To answer the question about, does it matter if it's a tooth off. No you are correct in your thinking. As long as you can get it timed, to what you want at idle,it doesn't matter.

[Jack Hidley]

It absolutely matters if the distributor is off teeth between it and the camshaft.

Drill a hole in the cap just inboard of the #1 electrode. Hook up a timing light to the #1 plug wire. Start the engine and point the timing light into the drilled hole. It will illuminate the rotor and electrode when the spark occurs. This enables one to see the relative phasing between these two parts when the spark occurs. You will see that at idle the spark jumps from nearly one end of the rotor electrode. This is because time timing will only be advanced about 10 degrees. If you were able to watch the spark under low load and medium rpm, you would see that the spark was happening at the opposite end of the rotor electrode because there is now 40 degrees of advance.

This is why the electrode on the rotor has a long arc shape to it. It needs to be long enough to handle the entire range of ignition advance that the engine will be used under. This is normally around a 40 degree range.

If you install the distributor and move it one tooth in either direction and repeat the experiment, you will find that the spark is now going to happen closer to one end of the rotor electrode in all cases. Under some amount of ignition advance, the spark will happen when there is a gap between the two electrodes, because it is past the end of the rotor electrode. When this happens the engine may totally misfire as the spark can't jump.

This is why Ford used octane rods on some of the distributors. This rod that goes into the side of the distributor rotates the baseplate which holds the Hall affect sensor. Doing so, allows a different base ignition timing to be used (for different fuel grade) while keeping the distributor engaged on the same cam tooth and having enough overlap between the two electrodes for the entire range of ignition advance curves.

[dynodon64]

Jack, no the distributor does not need to be on the right tooth of the cam. If you are using a crank trigger and are just using the distributor to carry the spark to the plugs only, then yes you need to get the distributor in phase to work with a crank trigger set up.

[Jack Hidley]

Do my experiment and it will prove that it does matter. If you install the distributor two teeth off, even though it is timed correctly, you will not even be able to start the engine because the spark won't be able to jump the gap.

If you don't believe me, explain why Ford put the octane rods in the distributor?

If I still had a car with a distributor, I'd video this and post it on YouTube to prove it.

[mmb617]

Interesting discussion you two guys are having. While I'm no expert I'm inclined to believe what dynodon says. I can't wrap my mind around any reason it matters where the distributor is placed as long as the #1 terminal is properly located at TDC on the compression stroke. All the cam gear does is spin the distributor shaft, it's the orientation of the distributor housing in relation to when it fires #1 that matters. At least that's been my experience.

My car has no vacuum advance and without that canister the distributor has clearance to be dropped almost anywhere. I've never worried about which tooth it's on when dropping it. I just bring #1 cylinder up on compression and make sure the rotor is pointing at the #1 terminal and the car fires up and can be timed from there.

I don't know anything about octane rods, what they are or why they'd be used, but the gap between the contact on the end of the rotor button as it rotates past the contact inside the distributor cap doesn't change regardless of where the distributor is stabbed. Rotating the distributor housing is what changes exactly when the gap between them is small enough for the spark to occur. From the description given it sounds to me like those octane rods are used to change the entire advance curve, no different than you could do by rotating the distributor housing. Perhaps it's just an easier way to alter the timing for different grades of fuel.

In my mind if the plug wires are installed in the correct sequence, and housing clearance wasn't an issue, you could stab the distributor on any cam tooth and rotate the housing to properly aim the rotor at #1 and the car would run. As far as that goes you should be able to drop the distributor anywhere you want then insert the plug wires into the cap so that the rotor is pointing at #1 (assuming you have #1 cylinder at TDC on compression stroke), as long as you insert the rest of the wires all in the proper sequence for your firing order.

As I said I'm no expert and I could be wrong, but I'm pretty sure my thinking on this is logical.