914-6 Conversion - Relay board to coil questions Options

[mtbr_mark]

Hi guys. I'm buttoning up a 914-6 conversion right now and ran into a problem the other night when I got the wiring hooked up (big surprise huh?). Turned the key to the on position then saw a waft of smoke floating by. Smoked the wires going to the hot side of the coil. I'm looking for anyone that's put a 2.0-6cyl engine into their 914 that can help. I've read tons and tons of posts on here about how the coil needs to be wired up but the problem comes in that everyone seems to give advice on wiring a 4-cyl coil (i.e. black/purple wire goes to one side and then black wire to other, blah blah blah).

I attached a quick schematic of how the 914-6 wiring is between the coil, the battery, the distributor, the Ignition box, and the relay board. As you can see there are a set of black/red wires coming from the relay board to the coil and the CD box. With the 4-cyl wiring harness there's only one black/red wire.

Anyhow, enough of my monologue here. Any help at all on how all my wiring needs to be to make my 1970 914-6 2.0 6cylinder motor work (wiring wise) in my 1971 914-4 2.0 4-cylinder car would be greatly appreciated.



Thanks,
Mark

[ClayPerrine]

This should help.....



But you won't have a tach if you use the factory 914-6 tach. There is no place for a tach amplifier. Use the tach out of an 911 SC and it will work fine.

[mtbr_mark]

This should help.....



But you won't have a tach if you use the factory 914-6 tach. There is no place for a tach amplifier. Use the tach out of an 911 SC and it will work fine.

I think that's exactly what I'm looking for. Thanks Clay. Just out of curiosity, have you personally wired up a 6-cylinder car using this info?

[ClayPerrine]

[quote name='mtbr_mark' date='Aug 6 2009, 12:56 AM' post='1199962']
[quote name='ClayPerrine' post='1199731' date='Aug 5 2009, 02:55 PM']
This should help.....



But you won't have a tach if you use the factory 914-6 tach. There is no place for a tach amplifier. Use the tach out of an 911 SC and it will work fine.
[/quote]

I think that's exactly what I'm looking for. Thanks Clay. Just out of curiosity, have you personally wired up a 6-cylinder car using this info?
[/quote


I drew the diagram, and I guarantee it works.



I built the wiring harness for my 73 six conversion car using a 73 914 harness, a 914-6 relay board, and parts of a 68 912 harness and a 75 911 harness. Yes, it will work, but like I said, you need an SC tach. The CD box on a 911 uses a lower voltage through the points, so there is not enough to fire the tach. When Porsche added the CD box to the 911, they used a "tach amplifier" which uppped the voltage to the tach, and they used the exact same parts on the 914-6. Later Porsche recalibrated the tach to work with the lower voltage.


Maybe I should start building 914/6 conversion harnesses?? (IMG:style_emoticons/default/idea.gif)

[mtbr_mark]

I drew the diagram, and I guarantee it works.


Maybe I should start building 914/6 conversion harnesses?? (IMG:style_emoticons/default/idea.gif)

Perfect. I hope I didn't come across as rude when I asked if you'd done this I just wanted to make sure that the rubber had met the road before I ran any current through my system again. Thank you VERY VERY much for the help. I'll get everything up and going like you suggest. Any leads on where to find a 911 SC Tach? (IMG:style_emoticons/default/smile.gif)