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Whaanga Samba Member
Joined: May 07, 2016 Posts: 625 Location: Rochester, NY
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Posted: Sat May 27, 2023 5:11 pm Post subject: A quick TDC/Timing Question |
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Hello All,
I'm thinking through a conceptual question and am seeking input from the CollectiveSambaWisdom.
When rotating and setting the timing on a type 4 engine, should the rotor be pointed directly at the wire connecter on the distributer? Or is there a 'range' within making an electronic connection with each spark plug wire?
I'm helping a fellow VW owner and noticed that when the engine is set at TDC on the scale, the rotor is not pointing directly at the spark plug wire but about 10 degrees off (the trouble is, now I can't remember if it's 10 degrees ahead or behind).
We removed the engine recently and as part of the process, removed the distributer. Before doing so, we carefully marked its setting and have returned it to the exactly the same place. As a reference, I checked my own type 4 engine and when the engine is rotated to TDC on any cylinder, the rotor is pointing directly at the spark plug wire boss on the distributer.
Why am I seeing two different behaviors from these two Type 4 engines? _________________ Late 1973 Bay w/a transplanted 914 Engine |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51125 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Sat May 27, 2023 5:15 pm Post subject: Re: A quick TDC/Timing Question |
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Because a spark can jump a somewhat large gap it just has to be in the ballpark, that's why most rotors have a fairly wide tip.
Points gap plays a big part in where the spark occurs, combine that with gear wear and mechanical advance movement and it's all over the place, what you see static doesn't always equate to running conditions. _________________ Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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Слава Україні! |
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bsairhead Samba Member
Joined: October 08, 2008 Posts: 3561 Location: viroqua wi.
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Posted: Sat May 27, 2023 6:10 pm Post subject: Re: A quick TDC/Timing Question |
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All that and points gap (dwell) |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50337
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Posted: Sat May 27, 2023 9:53 pm Post subject: Re: A quick TDC/Timing Question |
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In normal use the rotor to tower angle will change by around 30-35°. |
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Whaanga Samba Member
Joined: May 07, 2016 Posts: 625 Location: Rochester, NY
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Posted: Sun May 28, 2023 6:24 am Post subject: Re: A quick TDC/Timing Question |
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Thank You - This makes sense. _________________ Late 1973 Bay w/a transplanted 914 Engine |
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