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Sun Jul 25, 2021 7:02 pm

Hi, I have my stock 1300 engine on my 1966 beetle and I’m setting the ignition timing. I have stroboscopic light and am aligning the left hand mark on the pulley with the mark on the motor with the light set up to 7.5 degrees.
My question is: should I do this with the vacuum advance connected or disconnected?

Sun Jul 25, 2021 7:12 pm

Disconnected and the vacuum port on the carb sealed.

But it really depends on your distributor.

What ya running?

Sun Jul 25, 2021 7:40 pm

Don’t really know what distributor it is.
Here are some pictures

Sun Jul 25, 2021 7:47 pm

Looks like an SVA distributor.

Set it at 7.5° and check it with a timing light once you have it running and fully warmed up.

Sun Jul 25, 2021 7:54 pm

67rustavenger wrote: Looks like an SVA distributor.

Set it at 7.5° and check it with a timing light once you have it running and fully warmed up.

As you said, with the vacuum hose off and blocking the nipple on the carburetor?

Sun Jul 25, 2021 8:37 pm

No, on a SVA distributor keep the vacuum line connected. It is more accurate and a simpler procedure. The part number is facing the fan shroud. It's likely a 113 K which is static timed at 7-8 degrees BTDC. But it could also be a 113 M which is static timed at TDC. I'm making this assertion based on the short cap and large diameter vacuum canister. Static timing is ignition on but engine not running. After determining which distributor you have verify with your timing light that you are not getting more than 32 degrees total advance at full throttle.

Mon Jul 26, 2021 10:04 am

Today I checked the serial number on the distributor. It is a
JUR 4
0 231 137 009
113 905 205K
I appreciate if you can confirm me the correct timing for it and if the vacuum line should be connected or disconnected.

Mon Jul 26, 2021 12:09 pm

jlinares wrote: 0 231 137 009
113 905 205K
Here you go:
http://www.type2.com/~keen/ignition.html#A6667

Beetle 1966-1967 * 1300/1500
Distributor: VW 113-905-205K/L, Bosch 0231 137 009/010 > 315-905-205B, 0231 137 031
Can Use: VW 113-905-205M, Bosch 0231 137 021, 113-905-205T, 0231 137 035 or 036
Points: 01 009
Points Replacement Plate Assy: 1237 110 139
(Note: Order 01 013 Points if using this Plate Assy)
Condensor: 02 007 - Note: If equipped w/AC use 02 069
Rotor: 04 006
Cap: 03 001
Coil: 6 Volt - 00 001, 12 Volt - 00 015
Blue Coil: 6 Volt - 00 016, 12 Volt - 00 012
Vacuum Can: 07 017
Ignition Wires: 09 001
Spark Plug: W8AC
Timing Set At:: 7.5deg BTDC Static or @ 800-950rpm w/strobe w/vacuum hose disconnected and plugged
Advance/Retard Range: Vacuum (Advance Only): 17-19deg @ 1.3 In. Hg, 24-28deg @ 3.2 In. Hg

The question is, what timing marks do you have on your crank pulley? After decade of mods the timing marks on your crank pulley may not be correct for your installed distributor.
Setting your advance timing light to 7.5deg and lining up the TDC mark on your crank pulley with the case split is one way to time your ignition at idle if your crank pulley doesn't have a 7.5BTDC notch. If you have a 7.5BTDC notch, it may be easier to just set your timing light to 0-deg and line up the 7.5BTDC notch with the case split. It just depends which marking are on your pulley.

On the topic of whether the vacuum hose should be connected or not when checking your ignition timing at idle... check the timing with and without. At warmed up idle (800-950rpm) and the choke off, there should be no vacuum on the left side vacuum port (venturi vacuum). This means it should make very little difference. But if it matters... I say check it with the hose disconnected and plugged. :wink:

Mon Jul 26, 2021 7:15 pm

That will work.

Mon Jul 26, 2021 7:59 pm

ashman40 wrote: The question is, what timing marks do you have on your crank pulley? After decade of mods the timing marks on your crank pulley may not be correct for your installed distributor.
Setting your advance timing light to 7.5deg and lining up the TDC mark on your crank pulley with the case split is one way to time your ignition at idle if your crank pulley doesn't have a 7.5BTDC notch. If you have a 7.5BTDC notch, it may be easier to just set your timing light to 0-deg and line up the 7.5BTDC notch with the case split. It just depends which marking are on your pulley.

On the topic of whether the vacuum hose should be connected or not when checking your ignition timing at idle... check the timing with and without. At warmed up idle (800-950rpm) and the choke off, there should be no vacuum on the left side vacuum port (venturi vacuum). This means it should make very little difference. But if it matters... I say check it with the hose disconnected and plugged. :wink:

I have just 2 notches next to each other. I'm not sure, but from what I have learned doing research, they are 7.5 and 10 degrees from top dead center. And with my stroboscopic light, depending on what degrees I set it up to, the corresponding notches will line up with the cranckcase center line. Am I correct?

Mon Jul 26, 2021 8:59 pm

jlinares wrote: I have just 2 notches next to each other. I'm not sure, but from what I have learned doing research, they are 7.5 and 10 degrees from top dead center.
That sounds correct.
But without any other markings on your pulley you don't have a TDC indicator. This basically means you can't easily use the advance function on your timing light. The advance function was designed to work as the difference in degrees from TDC.
To avoid confusion, set your timing light to zero degrees and just use it like a traditional timing light which pulses when the spark plug fires.

jlinares wrote: And with my stroboscopic light, depending on what degrees I set it up to, the corresponding notches will line up with the cranckcase center line. Am I correct?
Not sure what you mean??? For example...
You rev your engine until the timing marks under the timing light stops advancing. While you hold the rpms here, you adjust your timing light until the 10BTDC mark lines up with the case split. You let the rpms drop to idle and your read the adjustment on the timing light and it shows 30deg. With this you know your distributor is maxing out at 40BTDC (30deg + 10BTDC = 40BTDC).
If this is what you meant... then Yes, you are correct and know how to use your timing light and its advance function.

If you instead, set your timing light to 8deg; adjust the idle timing so the 7.5BTDC notch lines up with the case split. Now you believe your idle timing is set to 8BTDC. No, this is incorrect. Your idle timing is now 15.5BTDC (8deg + 7.5BTDC = 15.5BTDC).

How are you adjusting your idle timing? Walk us thru the steps?

Mon Jul 26, 2021 9:53 pm

ashman40 wrote: If you instead, set your timing light to 8deg; adjust the idle timing so the 7.5BTDC notch lines up with the case split. Now you believe your idle timing is set to 8BTDC. No, this is incorrect. Your idle timing is now 15.5BTDC (8deg + 7.5BTDC = 15.5BTDC).

How are you adjusting your idle timing? Walk us thru the steps?

Then I'm doing it wrong, I do more of what you say at the end.
What I do is first, warm up the engine, then loosen the distributor, take my light, put it to 7 degrees and look at the marks. I switch the light to 7 and 8 repeatedly to kind of estimate 7.5 degrees. What I look for is that the left hand mark on the pulley is aligned with the case line. If it isn't, I slightly rotate the distributor until it is. This I do it in idle speed, and don't mind so much the revolutions.
I saw this in a youtube video, maybe if you have a video that explains what you're saying I appreciate if you post the link.

This is the way I have timed it since I do it myself, about 2 years ago. I recently am timing it up again because about 3 months ago a mechanic replaced a broken part of my carb and left the car choking a lot, so while tuning the carburetor, I checked the ignition timing too and this time I asked myself, which I never did before, if the vacuum should be connected or not.
Now I'm very confused. Seems like I've been doing it wrong the whole time although before the carburetor damage, I felt like it ran perfectly.

Thank you for the help.

Tue Jul 27, 2021 7:25 am

The advance timing lights (the ones with adjustable degree settings) were meant to be used with a TDC mark. If you want to set your timing to 13BTDC you don't need a 13BTDC mark, you just set the timing light to 13deg and line up the TDC mark, done.
Want to check if your max ignition timing is 28BTDC? Set the timing light to 28deg, rev the engine and confirm that the TDC mark lines up, done.

It is a very handy timing light when you have a TDC mark. Since most cars have a TDC reference it works for most cars. Unfortunately, your crank pulley does not have a TDC mark. But you can add one!
Either measure 7.5deg CCW from the 7.5BTDC mark... break out your geometry skills and figure out how many inches 7.5deg is around the circumference of a 7inch pulley (circle).
Or you can print out a paper degree wheel and place it over the pulley. Line up the 7.5 and 10deg lines then you can mark where the TDC is on the edge of your pulley.

Once you have a TDC paint mark on the pulley, using the advance timing light will make more sense.

Until then, just set the timing light to 0-deg and use it the "old school" way... line up the 7.5BTDC notch with the case split and your timing is 7.5BTDC.

Tue Jul 27, 2021 6:44 pm

a TDC paint mark is also useful when you need to do a valve tappet adjustment.