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Wiring for stock ignitor w. fixed timing (no ecu)?

Posted: Mon Jul 04, 2016 10:16 am
by erictharg
I want to run the stock distributor (4 pole trigger) straight to the ignitor module with fixed timing as I'm not using an ECU (on carbs). Anyone know the correct wiring to do this? As suggested on Bill Sherwood's old page...
Thanks,

Re: Wiring for stock ignitor w. fixed timing (no ecu)?

Posted: Mon Jul 04, 2016 3:07 pm
by jondee86
I think that you will need to replace the stock igniter with something like this...

Image

Image
https://dgtlmoon.com/bosch_bim_024_elec ... ion_module

I've never tried the conversion, but it seems to be the low cost DIY conversion.
Plenty of threads like the above around, so do some research before you decide
which way to go.

Cheers... jondee86

Re: Wiring for stock ignitor w. fixed timing (no ecu)?

Posted: Mon Jul 04, 2016 3:17 pm
by sirdeuce
Be better to go with something like an MSD 6A, you'd have the option of a rev limiter. Cost is not excessive and wiring is simple enough. You can post in the "want to buy" section and probably find one for a reasonable price.

Re: Wiring for stock ignitor w. fixed timing (no ecu)?

Posted: Mon Jul 04, 2016 3:28 pm
by sirdeuce
As for wiring the stock igniter. If yours is USDM AFM, the distributor signal goes to the igniter, then from the igniter to the ECU and back to the igniter. The distributor pick-up ground would go to the igniter to ECU ground and the + signal from the distributor would go to the terminal where the ECU's signal goes to the igniter. I could give you specifics if I had access to my wiring diagrams, but all is packed again as we are moving. It is simple enough. Wiring per Sherwoods site is easier as the wiring is a bit different. Their dizzy signals go directly to the ECU so they just bypass the ECU.

Re: Wiring for stock ignitor w. fixed timing (no ecu)?

Posted: Mon Jul 04, 2016 4:21 pm
by Jeff Lange
The stock igniter can definitely do this, and it's actually pretty easy to get working as well, since without an IGt input, it will just run at 10 degrees BTDC timing advance (which you could adjust stlightly to get a bit more advance for fixed timing).

Jeff

Re: Wiring for stock ignitor w. fixed timing (no ecu)?

Posted: Mon Jul 04, 2016 6:58 pm
by jondee86
True that ^^^^ on the VAST ignition system :) If the pickup wires connect directly
to the igniter and not to the ECU, then the engine will run at initial timing without
the ECU. IIRC initial timing is 10deg, so you would need to bump that up to around
25-30deg. Some experimentation may be required to find a setting that allows the
engine to start while still making good power.

If you don't have the VAST ignition system (pickup wires connect to ECU) then the
engine will not run, as the ECU has to be there to generate the trigger signal for
the igniter. In that case you need something like the Bosch module (fixed advance)
or a MSD, Hyperpack type module with built-in advance, or a modified K-series dissy.

Cheers... jondee86