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Raycgainey
Samba Member
Joined: April 03, 2020
Posts: 9
Location: Greenwood, Indiana
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 Posted: Wed Mar 20, 2024 8:29 pm Post subject: Distributor drive gear installation |
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| Simple question is this: Does the slot in the distributor drive gear have to line up parallel with the rear of the engine, parallel to the pulleys? I've found half a dozen manuals indicating that this is the correct orientation of the gear shaft. However, I've seen posts in the forum that seem to indicate this isn't critical. Am I just not understanding? My '71 Super is proving very difficult to time. The drive gear shaft is at 40 degrees off from parallel to the rear of the engine. Would that make it difficult or impossible to set the timing correctly? |
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kreemoweet
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Joined: March 13, 2008
Posts: 3900
Location: Seattle, WA
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| Posted: Wed Mar 20, 2024 9:43 pm Post subject: Re: Distributor drive gear installation |
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It's the "standard", factory-set setup position. It is not critical in that the engine can be properly timed in just about any position of the distributor drive, but the distributor may end up in a weird position, and the spark plug wires will end up godknowswhere.
All ya have to do to be one of the "correct" fellers is to make sure the engine is at TDC on the compression stroke of cylinder #1, then lift up the drive and drop it back down so it ends up in the "standard" position. Ignition wires may have to be moved, and distributer twirled around to get right timing.
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Glenn 
Mr. 010
Joined: December 25, 2001
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| Posted: Thu Mar 21, 2024 5:15 am Post subject: Re: Distributor drive gear installation |
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bsairhead
Samba Member
Joined: October 08, 2008
Posts: 3590
Location: viroqua wi.
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| Posted: Thu Mar 21, 2024 7:01 am Post subject: Re: Distributor drive gear installation |
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| kreemoweet wrote: |
It's the "standard", factory-set setup position. It is not critical in that the engine can be properly timed in just about any position of the distributor drive, but the distributor may end up in a weird position, and the spark plug wires will end up godknowswhere.
All ya have to do to be one of the "correct" fellers is to make sure the engine is at TDC on the compression stroke of cylinder #1, then lift up the drive and drop it back down so it ends up in the "standard" position. Ignition wires may have to be moved, and distributer twirled around to get right timing. |
Should read ,can be properly timed in any position. I have not seen an engine were the vacuum can hits no matter where the distributor is located. |
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Busstom
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Joined: November 23, 2014
Posts: 3855
Location: San Jose, CA
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| Posted: Thu Mar 21, 2024 8:17 am Post subject: Re: Distributor drive gear installation |
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This image that VW produced would seem convenient if it weren't so subtly misleading; I don't think I've ever seen an engine where the drive slots were ever truly perpendicular to the case seams, it's always off a couple/few degrees (if I recall correctly, CCW to this image, but either way still).
So don't let that worry you if your final result doesn't look exactly like the picture.
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Cusser
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Joined: October 02, 2006
Posts: 31389
Location: Hot Arizona
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| Posted: Thu Mar 21, 2024 8:24 am Post subject: Re: Distributor drive gear installation |
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| kreemoweet wrote: |
All ya have to do to be one of the "correct" fellers is to make sure the engine is at TDC on the compression stroke of cylinder #1, then lift up the drive and drop it back down so it ends up in the "standard" position. Ignition wires may have to be moved, and distributer twirled around to get right timing. |
If I remember correctly, the fuel pump flange needs to be removed to pull up or re-orient the distributor drive shaft.
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bsairhead
Samba Member
Joined: October 08, 2008
Posts: 3590
Location: viroqua wi.
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| Posted: Thu Mar 21, 2024 11:30 am Post subject: Re: Distributor drive gear installation |
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| Cusser wrote: |
| kreemoweet wrote: |
All ya have to do to be one of the "correct" fellers is to make sure the engine is at TDC on the compression stroke of cylinder #1, then lift up the drive and drop it back down so it ends up in the "standard" position. Ignition wires may have to be moved, and distributer twirled around to get right timing. |
If I remember correctly, the fuel pump flange needs to be removed to pull up or re-orient the distributor drive shaft. |
Yes some do. The pump and rod for sure. |
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KTPhil
Samba Member
Joined: April 06, 2006
Posts: 34023
Location: Conejo Valley, CA
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| Posted: Thu Mar 21, 2024 12:02 pm Post subject: Re: Distributor drive gear installation |
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| Busstom wrote: |
This image that VW produced would seem convenient if it weren't so subtly misleading; I don't think I've ever seen an engine where the drive slots were ever truly perpendicular to the case seams, it's always off a couple/few degrees (if I recall correctly, CCW to this image, but either way still).
So don't let that worry you if your final result doesn't look exactly like the picture. |
And furthermore, it will rotate slightly as it bottoms out and meshes with the crank gear. It should end up close to this position, but it doesn't start there. |
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ashman40
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Joined: February 16, 2007
Posts: 15989
Location: North Florida, USA
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| Posted: Thu Mar 21, 2024 12:50 pm Post subject: Re: Distributor drive gear installation |
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| Raycgainey wrote: |
| Simple question is this: Does the slot in the distributor drive gear have to line up parallel with the rear of the engine, parallel to the pulleys? ... The drive gear shaft is at 40 degrees off from parallel to the rear of the engine. Would that make it difficult or impossible to set the timing correctly? |
As with most things the answer is... "It depends" 
Short answer, most of the time the position of the drive gear down in the case has no direct impact on being able to correctly set ignition timing. So for most cases the 40deg gear offset just means the #1 spark plug will be 40deg offset from where it would normally be located around the cap. For most, this is not a problem.
When does it become a problem? Typically when the 40deg gear rotation forces you to rotate the distributor body and the vacuum canister ends up contacting the intake manifold or the fuel pump. In most cases, when the drive gear is installed correctly the vacuum canister will be at the 7-o'clock position as viewed from the rear of the car. This allows reasonable CW and CCW rotation to adjust ignition timing. If the incorrectly installed distributor forces you to rotate the distributor so that the canister has very little room to move you may lack the needed adjustment room to time the ignition correctly.
Solution = In most cases, if you don't like how your distributor is oriented, you can
1) Rotate the engine until the rotor is pointing to the #1 plug wire post on the cap and the timing notch on the crank pulley is lined up near the case split. Note where the rotor is pointing. Different distributors place the #1 distributor post in different spots.
Remove the spark plug wires from the distributor cap.
Rotate the distributor body in 90deg increments You will need to readjust timing as most "mere mortals" cannot rotate the distributor exactly 90degs. 
Reinstall the spark plug wires starting with the #1 spark plug wire onto the post which is now over the tip of the rotor. The remaining wires are installed in the CW firing order 1-4-3-2.
If you can, static time the distributor to 7BTDC just to get the engine running. Are you able to adjust the timing with some room to make adjustments? Will another 90deg position work better?
Once you get the engine running, use a strobe timing light to set the ignition timing correctly for the model distributor you have installed. Do not set ignition timing based on your model year unless you have the original model distributor and carb still installed. If you changed the distributor to a different model, adjust timing for THAT model distributor.
There is another problem for a small group of OE distributors... in the late '60s (maybe also early '70s??) VW released a few distributor models with a retarded #3 plug wire position. This only came on SP engines as a means of cooling the #3 cylinder as it lacked good air ciculation. The later DP engines fixed this so later distributor models did not have this retarded #3. For these distributors, you really cannot randomly rotate the distributor 90deg because you will be changing which cylinder is retarded. The notch on the rim of the distributor indicates where the #1 plug wire should be installed. For these special retarded #3 distributors the post opposite the notch is the one retarded a few degrees.
How do you know if your distributor has the retarded #3? Using a strobe timing light check the idle ignition timing for cylinders #1 and #3. You do this by moving the indictive clamp from plug wire #1 to #3. Under the strobe light the timing marks on the pulley should be in the same place regardless of whether you connect to #1 or #3.
For cylinders #2 & #4 you need to add a reference mark on the crank pulley 180deg from the TDC mark. It doesn't need to be perfect as it is just a common reference point. This mark is also used when setting valve clearance. Neither requires it be exactly at BDC. Within a few degress is fine.
Check timing for both #2 and #4 cylinders and make suure their sparks are firing at nearly the same timing. The BDC mark will look the same for both cylinders.
If you find that one cylinder is noticeably different (retarded) from its opposing cylinder it means one of your cylinders is retarded at the distributor. I believe this is done at the cam lobes that open the point contacts. You (as the mechanic) must make sure this retarded post on the distributor is connected to the #3 cylinder which is opposite the #1 plug wire on the cap (notch). Installing the plug wires into the cap in any other orientation means you are instead retarding one of the other 3 cylinders and giving up power unnecessarily.
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KTPhil
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Joined: April 06, 2006
Posts: 34023
Location: Conejo Valley, CA
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| Posted: Thu Mar 21, 2024 1:42 pm Post subject: Re: Distributor drive gear installation |
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Yep:
And on some Type 3 engines, too:
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15989
Location: North Florida, USA
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| Posted: Thu Mar 21, 2024 2:01 pm Post subject: Re: Distributor drive gear installation |
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| Raycgainey wrote: |
| The drive gear shaft is at 40 degrees off from parallel to the rear of the engine. |
I forgot to mention... the drive gear down in the case has 12-teeth. This means adjusting its position by 1 tooth = 30deg changes (360 / 12 = 30deg). If your slot appears to be off by 40deg from parallel to the crank pulley... adjusting it by 1 tooth should place it 10deg offset in the opposite direction.
As mentioned earlier, don't expect it to be perfectly parallel (nor should you expect it to be perfectly perpendiculare to the case split). But 10deg is much closer than 40deg. 
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