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pop.pop1955 Samba Member
Joined: October 31, 2021 Posts: 46 Location: Palm Coast, Fl.
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Posted: Sun Jun 26, 2022 7:54 am Post subject: checking dwell |
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I just replaced pts. cond. cap and rotor on my 71 super beetle. I wanted to check the dwell and timing. however when I hook up the timing light/ dwell meter the car stalls. If I hook it up and try to start the car it won't start. Otherwise the car runs and sounds good. Any thoughts? _________________ let your conscious be your guide |
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Cusser Samba Member
Joined: October 02, 2006 Posts: 31387 Location: Hot Arizona
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Posted: Sun Jun 26, 2022 8:05 am Post subject: Re: checking dwell |
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pop.pop1955 wrote: |
I just replaced pts. cond. cap and rotor on my 71 super beetle. I wanted to check the dwell and timing. however when I hook up the timing light/ dwell meter the car stalls. If I hook it up and try to start the car it won't start. Otherwise the car runs and sounds good. Any thoughts? |
Let's assume that you have positive meter cable on positive, negative cable on negative - and feed cable to the NEGATIVE terminal #1 on the coil. If all that is correct, and still stalls, I might try the meter on a different older vehicle. If that doesn't work as well, likely something with the meter, and I'd just rely on the points gap to be 0.016 inches as you measured with your feeler gauge - like we did this in the old days when we couldn't afford a dwell meter !!! _________________ 1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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cletus_zuber Samba Member
Joined: January 08, 2010 Posts: 2408 Location: Gladstone, Ore
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Posted: Sun Jun 26, 2022 8:19 am Post subject: Re: checking dwell |
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This side of the road method works great. _________________ 1972 1302
HPMX 40's & 019 |
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Cusser Samba Member
Joined: October 02, 2006 Posts: 31387 Location: Hot Arizona
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ashman40 Samba Member
Joined: February 16, 2007 Posts: 15989 Location: North Florida, USA
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Posted: Mon Jun 27, 2022 5:54 am Post subject: Re: checking dwell |
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You need to describe how you have your light/meter connected. I suspect one of two issues:
1) The meter is grounding the #1 (-) terminal of the ignition coil. This would prevent the coil from firing. This is probably and indicator of a bad meter.
2) You are powering your light/meter from the ignition coil #15 (+) terminal. While this may be the most convenient point to get 12v+ From, any additional devices connected here take current away from the ignition coil. Over time the wire to the ignition coil increases internal resistance and limits the current that will make it to the ignition coil. All the devices connected to the #15 terminal must share this limited amount of current.
This used to happen on my old ‘75. Engine would run but as soon as I triggered the timing light you would hear the rpms drop and eventually the engine would die. This was the timing light pulling current away from the coil and weakening the spark that made it to the spark plugs.
Try a different power source for the timing light. If you have an alternator, the B+ terminal is the same as connecting to the battery + terminal. Worse case, use your battery jumper cables to extend the battery terminals to the engine compartment where you can connect the timing light to the other end. _________________ AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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BMFBMF Samba Member
Joined: November 13, 2020 Posts: 358 Location: Swtzerland
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Posted: Mon Jun 27, 2022 6:52 am Post subject: Re: checking dwell |
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In the motorcycle world one always uses a second battery to power the timing light. There are too many potential problematic interactions. |
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ashman40 Samba Member
Joined: February 16, 2007 Posts: 15989 Location: North Florida, USA
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Posted: Mon Jun 27, 2022 12:12 pm Post subject: Re: checking dwell |
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BMFBMF wrote: |
In the motorcycle world one always uses a second battery to power the timing light. There are too many potential problematic interactions. |
Beetle engines suffer from this problem because the battery is not in the engine compartment. Most (but not all) other cars have the battery in or near the engine compartment where it can be used while setting the ignition timing. Tapping the battery to power the timing light is the best source. Having a spare 12v battery, even a drycell 12v battery is convenient, but usually not required. Last time we timed the ignition my buddy rolled his motorcycle up so we could use its battery as a power source. _________________ AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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raydog Samba Member
Joined: February 09, 2006 Posts: 1163 Location: Cape Cod
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Posted: Mon Jun 27, 2022 12:38 pm Post subject: Re: checking dwell |
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Yes, direct from the battery is the best and easiest source for power. With my VW, I have always tapped power at the D+ generator terminal or the 12v source at the coil. Any downfall to doing it this way? Although I did get whacked twice with ignition voltage that sent me on my ass. I chalked it up to being a metal timing light with a bad ground. I still have a small scar on my knee from when I hit the curb. _________________ Come on, It's not rocket science. KISS |
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ashman40 Samba Member
Joined: February 16, 2007 Posts: 15989 Location: North Florida, USA
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Posted: Wed Jun 29, 2022 7:48 am Post subject: Re: checking dwell |
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raydog wrote: |
Yes, direct from the battery is the best and easiest source for power. With my VW, I have always tapped power at the D+ generator terminal or the 12v source at the coil. Any downfall to doing it this way? |
As described above… old wires with high resistance will limit the amount of current that can reach the end of the black #15 wire that powers the ignition coil. If there is just enough to power the coil and other devices powered from the wire (eg. idle cutoff solenoid, choke, reverse lights) any additional devices drawing current will draw that current away from the ignition coil; reducing the power available to spark the spark plugs.
raydog wrote: |
Although I did get whacked twice with ignition voltage that sent me on my ass. I chalked it up to being a metal timing light with a bad ground. I still have a small scar on my knee from when I hit the curb. |
Normally getting a shock from the ignition system (10,000v+) means there is a gap in the plug wire insulation. Even a small crack in the insulation can allow a spark to jump from the wire to any grounded item… like your hand/arm. As a test for this, ground one end of a wire and pass the striped other end along the length of the spark plug wire. You might even fashion a loop that you can pass around the plug wire. Do this in the evening when you can turn off the lights and more easily see sparks jumping from the spark plug wires to the striped end. Some will also spray water around the wires as another way to offer an alternate path for sparks. _________________ AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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