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Maineshops Samba Member
Joined: April 23, 2016 Posts: 29 Location: Ludlow maine
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Posted: Mon May 09, 2016 4:29 pm Post subject: Dwell tach |
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Got the dwell tach today and it seems squirrelly . Bounces around so it is unreadable. Red wire to coil ,distributer , and black to bat neg. any ideas what is going on? Name is standard digital multimeter. Thanks Dan |
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sjbartnik Samba Member
Joined: September 01, 2011 Posts: 5986 Location: Brooklyn
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Posted: Mon May 09, 2016 4:46 pm Post subject: Re: Dwell tach |
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Ah the eternal question: is your dwell/tach screwy or is your distributor nice and worn out? _________________ 1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
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Glenn Mr. 010
Joined: December 25, 2001 Posts: 76761 Location: Sneaking up behind you
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Posted: Mon May 09, 2016 5:34 pm Post subject: Re: Dwell tach |
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Try it on another engine. _________________ Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
#BlueSquare |
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Maineshops Samba Member
Joined: April 23, 2016 Posts: 29 Location: Ludlow maine
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Posted: Tue May 10, 2016 4:42 am Post subject: Re: Dwell tach |
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It dosen't appear to have excessive wear . What would I look for ? I had the tach close to the engine. Could I be picking up noise from the plug wires? |
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kenj06 Samba Member
Joined: November 28, 2011 Posts: 198 Location: Ohio
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Posted: Tue May 10, 2016 9:39 am Post subject: Re: Dwell tach |
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If your dwell meter is digital, it certainly could be interference from ignition. I had that problem with my old set of plug wires, couldn't get steady voltage, rpm, or any other readings on digital equipment. New set of plug wires and everything was fine. |
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Maineshops Samba Member
Joined: April 23, 2016 Posts: 29 Location: Ludlow maine
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Posted: Tue May 10, 2016 2:10 pm Post subject: Re: Dwell tach |
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Yes digital....Sineometer ut100. Company makes a bunch of these so I guess it should be fairly reliable.
I've looked at the blue wires in the dark and can't see any leakage but old eyes play tricks n me too.
Any way to check for noise? |
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kenj06 Samba Member
Joined: November 28, 2011 Posts: 198 Location: Ohio
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Posted: Wed May 11, 2016 8:22 am Post subject: Re: Dwell tach |
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Well if you get a lot of static on the radio and it changes with RPM, that is always an indicator. The wires could be non-suppression which would cause the same issue.
As suggested, check the dwell on another vehicle to verify the meter is good. |
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Maineshops Samba Member
Joined: April 23, 2016 Posts: 29 Location: Ludlow maine
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Posted: Wed May 11, 2016 2:23 pm Post subject: Re: Dwell tach |
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Don't have a radio or another engine with points. I wonder if I can put a resistor inline with the meter to settle it down? What size resister? |
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Maineshops Samba Member
Joined: April 23, 2016 Posts: 29 Location: Ludlow maine
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Posted: Tue May 17, 2016 4:41 am Post subject: Re: Dwell tach |
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As per Ken's advice I put new bosh wires in and that solved the tach jumping around problem thanks
However the tach reads steady at about 325 but by ear it seems to be idling about right for a vw if memory serves me. But it's been about 30 yrs since I worked on one. |
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kenj06 Samba Member
Joined: November 28, 2011 Posts: 198 Location: Ohio
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Posted: Tue May 17, 2016 8:48 am Post subject: Re: Dwell tach |
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bad wires will do that. affected my voltage measurements on the generator for me.
Is it possible the tach has a 4,6,8 cylinder position and it's in the 8 position or do you need to double the reading for a 4 cyl? |
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Maineshops Samba Member
Joined: April 23, 2016 Posts: 29 Location: Ludlow maine
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Posted: Tue May 17, 2016 3:20 pm Post subject: Re: Dwell tach |
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Yes this one has 3,4,6,8 and it is set on 4. It is a puzzle but I learn with every challenge . I'll try the 8 setting and see if there is any coralation between the two. |
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Mark Lewalski Samba Member
Joined: June 19, 2010 Posts: 405 Location: Safety Harbor, FL (Tampa Bay)
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Posted: Tue May 17, 2016 9:46 pm Post subject: Re: Dwell tach |
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I used an analog dwell meter and had no problems.
I referenced Rob and Dave's tune up procedure:
http://vw-resource.com/tune_up.html
Although kind of lengthy, it explained everything I needed to know. I just printed out the whole thing so I could reference it while at the engine.
Rebuilding the carb at the same time made a huge difference when I did the full tune up. Everything ran very nicely since the whole system was refreshed and worked on as a whole.
Mark _________________ '89 Vanagon GL Wolfsburg "Bluestar" (given to and owned by my son now)
'87 Vanagon Weekender
'74 Thing |
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Maineshops Samba Member
Joined: April 23, 2016 Posts: 29 Location: Ludlow maine
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Posted: Wed May 18, 2016 5:39 am Post subject: Re: Dwell tach |
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I have Rob and Daves printed out too. I've cleaned the carb and replaced o rings and gaskets. I'm going to try to set the fast idle with a feeler gauge today. Can't do it by eye and get it accurate and from what I read that is critical to do the other two adjustments right.
Finding "stuff" here in northern Maine is a pain. Will a dashboard tach work? I may be able to find one of them |
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