New Distributor-Initial Timing Help

Helllo All,

I've went through a nightmare of a distibutor replacement. the olld one was nearly impossiby seiv=zed into the block but I removed it (pictures to be added) put the new one in and now I've having throuble setting the initial timing.

What Ive tied

1. No 1 Cyl to TDC (with 0Degr timing mark on Harmonic Balancer confirmed with compression tester)
2. Lined up No 1 Terminal on Dist Cap and made a mark on housing
3. Lined up housing to rotor and inserted into Block and engaged with Oil pump Shaft
4. Replaced spark plug and attached No 1 Spark Wire
5. Fired up the engine
6. Idles on choke High Idle appox 1500 RPM (timing marks show 20-ish dgrs before TC (BTC)
7. after it warms up it begins to idel rough and  now I cant see the timing marks

What is going on?

I confirmed the dis. has not moved.

Please Help.

I am sure you will get better advice.

Sounds like a lot of timing. With the vacuum advance (if you have it) disconnected try to get the initial timing to 10-12DBTDC.

What is your warm idle speed set too? Is it very low? I think ~750 would be a good target. If you are at ~550 it could be rough, my 351w is happy about 700. More in the winter less in the summer.

Oh, and check your firing order. People have commented in the past about having a 302 firing order on 351w after a rebuild.. an outside option I know.. change the spark leads around, real easy test!

Thank for any info,

I'll check the firing order today that has been on my list, and provide an update

What kind of timing light are you using? If it's the kind that supports "dial-back", make sure you have it dialed back to zero. This can either be a knob on the gun, or up/down buttons if the gun is newer.

Make sure the vacuum advance is disconnected at the distributor, and make sure to cap the hose somehow, otherwise you will have a vacuum leak and it might idle higher. Capping the can on the distributor is not necessary.

With the gun at 0 on the dialback (or if it's not a dial-back type gun), see if you can pick up the timing marks. Taking a silver or white marker and making a big stripe where you want the initial timing to be can help. Start with about 8 btdc if your engine is stock-ish.

Once you have that established, the procedure differs depending on if you have a dial-back gun or not.

Dial-back:

Dial the gun back to the desired total timing (probably somewhere in the 34-36 degrees btdc range). Rev the engine to about 3500 and observe where the timing is at. A lot of people like to set the timing based on max advance at higher RPMs, and then let the idle timing fall where it may.

No Dial-back:

Use geometry to calculate how far on the circumference of your harmonic balancer is 34-36 degrees. You can kind of approximate this because they give you a 0 to -10 stamped on the balancer, so about 3.5x that distance from 0 will get you there. Make a red stripe across the balancer there. Alternative: places like Summit or Jegs also sell what's called "timing tape", there are different versions according to the diameter of your balancer. Get the right size and then you will have timing marks all the way around your balancer so you can see where it is if you can't see the factory marks.

Whichever method you use, if you find that you can't obtain acceptable (compatible) readings at both ends of the scale (idle, and above 3500), then you need to tinker inside the distributor. If the range is too big, most distributors can have stops installed, to limit the total timing. If the range is too small, you can install lighter springs. Or if the curve is not acceptable, you can install different springs, depending on what you need. You can measure/plot your curve by taking readings every 500 rpm between idle and 4000 rpm.

Finally, remember to reconnect the manifold vacuum.

What kind of timing light are you using? If it's the kind that supports "dial-back", make sure you have it dialed back to zero. This can either be a knob on the gun, or up/down buttons if the gun is newer.
Yes Pete, it's a newer light and it has buttons that I confirmed they are not adding any advance.

Make sure the vacuum advance is disconnected at the distributor, and make sure to cap the hose somehow, otherwise you will have a vacuum leak and it might idle higher. Capping the can on the distributor is not necessary.

Yes, Did that.

With the gun at 0 on the dial back (or if it's not a dial-back type gun), see if you can pick up the timing marks. Taking a silver or white marker and making a big stripe where you want the initial timing to be can help. Start with about 8 btdc if your engine is stock-ish.

Cleaned the balenacer, and added paint to make sure I could see the marks and numbers, and started with 8Dgrs, right where I set it, unfortunately while i was running and warming it up, the timing shifted?

Once you have that established, the procedure differs depending on if you have a dial-back gun or not.

Dial-back:

Dial the gun back to the desired total timing (probably somewhere in the 34-36 degrees btdc range). Rev the engine to about 3500 and observe where the timing is at. A lot of people like to set the timing based on max advance at higher RPMs, and then let the idle timing fall where it may.

No Dial-back:

Use geometry to calculate how far on the circumference of your harmonic balancer is 34-36 degrees. You can kind of approximate this because they give you a 0 to -10 stamped on the balancer, so about 3.5x that distance from 0 will get you there. Make a red stripe across the balancer there. Alternative: places like Summit or Jegs also sell what's called "timing tape", there are different versions according to the diameter of your balancer. Get the right size and then you will have timing marks all the way around your balancer so you can see where it is if you can't see the factory marks.

 my Balancer goes up to 30 dgrs,  If thee tuning of the initial timing should be 34-36dges at 3500? My light can do that, is this without the vac adv plugged in still?

Whichever method you use, if you find that you can't obtain acceptable (compatible) readings at both ends of the scale (idle, and above 3500), then you need to tinker inside the distributor. If the range is too big, most distributors can have stops installed, to limit the total timing. If the range is too small, you can install lighter springs. Or if the curve is not acceptable, you can install different springs, depending on what you need. You can measure/plot your curve by taking readings every 500 rpm between idle and 4000 rpm.

 This is great info Pete, Thanks for this I'll try this approach tomorrow

Finally, remember to reconnect the manifold vacuum.

Bulletproof250 wrote

Cleaned the balenacer, and added paint to make sure I could see the marks and numbers, and started with 8Dgrs, right where I set it, unfortunately while i was running and warming it up, the timing shifted?

Are you saying that the initial timing shifted?  Meaning that you have the vacuum hose pulled off and at ~650 RPM (idle) the timing changed after you started?

If so then it sounds like your harmonic balancer is slipping.

Yes, the entire timing procedure should be done with the manifold vacuum disconnected.

On the 34-36 degrees at 3500, that's just a ballpark. Many variables affect what your actual max timing should be. For example, a more modern combustion chamber shape in a newer aluminum head will require less advance, more like 31-33 degrees. Compression ratio, piston shape, and other factors also play a role. In general, if you have factory iron heads, 34 is a good number to shoot for, but that can certainly be tuned to what your engine likes.

I'm also unclear on "the timing shifted". Do you mean you didn't have the distributor tightened down enough and the housing moved because of the rotation of the shaft within it? Or do you mean it was all bolted down good and tight and the timing moved without the distributor slipping? If that happened, Gary is right, your balancer is slipping and you need a new one.

Thanks Gary, and Pete again,

 Gary
To your point, I was concerned about this as well, but since I am able to bring the timing back to 0 dgrs, and TDC multiple times, I thought that this would disprove this as a factor, this will be my first experience with a slipping harmonic balancer, although I've heard about it plenty of times.

 Pete

I haven't retried it today (went fishing for a bit) before Hurricane Nicole's remnants cause too much wind and rain.
This is leading up to the install which I will use the pullies I believe that you sent to me a while back.

I'm looking forward to having this solved this weekend, but i'm quickly losing momentum, in frustration.

Thanks again for your time,

Lesson Learned

Don't let this happen to you:

It looked like a great place to store the timing light while I made the necessary adjustment. However between the Radiator support and the Battery was the MAIN issue all along, It kept hitting the advance button on the light and when I picked it up again, viola!, timing appeared to have changed.


  

So the timing is fine, it was just that the advance button was pushed?  Problem solved, there was no problem?

That's correct Gary,

The problem in the timing, was the interface of the timing light and the person operating it!

I've got the truck running fantastic, but I'm open to any tips on adjusting the Vac advance.

Vacuum advance is the last timing element to adjust.  First is initial, and it is usually the factory setting plus 2 - 4 degrees.  Then mechanical/centrifugal, and it is frequently left stock - especially given the trouble it is to get to the springs on a Ford dizzy.  Then vacuum.

On that, I use the very small Allen wrench (3/32") to move the stop to allow more advance until I get pinging with part throttle in a high gear for the situation.  And then I take some advance out until the pinging stops.  Said another way, you need a relatively high gear to put a load on the engine at fairly low RPM, like maybe 1500 - 2000.  But you need to only be giving it part throttle so the vacuum stays high and the advance comes in.

But the Crane instructions (Documentation/Electrical/Ignition and then the Instructions tab and then the Crane Cam Instructions tab) do a better job of explaining:

23. Check for full clockwise adjustment and connect the adjustable vacuum advance unit to the manifold vacuum source. (FIG. 17)

24. Test-drive the vehicle in the city and on the highway while listen­ing for audible spark knock under heavy load and part throttle. If spark knock occurs under part throttle conditions, a change in the vacuum advance curve is needed. This adjustment is made by inserting the 3/32” alien wrench into the vacuum advance unit and turning the adjuster counterclockwise two turns at a time, testing the vehicle after each change, until part throttle spark knock is eliminated.

That's Great Gary that's the same place that I started with (Crane Cams).

However, when you describe the initial timing being "...the factory setting plus 2 - 4 degrees"

If the Factory for my Truck is 8° BTDC

Does that mean my initial timing could be 10°-12° BTDC?

I have desmogged this engine and plugged the heads, I think I've seen somewhere on this forum some claim to re-adjust after be about 5° BTDC.

Just curious if I need to review the initial timing or is the Vac Advance my last step.

Thanks again to the Bullnose Crew

Yes, you can add 2 to 4 degrees the the factory spec.

So I’d set initial to 10 or 12 and see if it starts ok hot. If it kicks back when starting hot take out a couple of degrees.

Then worry about vacuum when the initial is set.