1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

CAS and FD coils

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Old Feb 1, 2014 | 02:07 PM
  #1  
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Kim
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CAS and FD coils

Hi.
Well the deal is, that my friend and I decided to do a DFIS on his FB - using parts from the parts bin

My head is hurting from thinking this through so a little help is needed.

We want to use: 13B Cosmo CAS (similar to S5)
FD igniter and coils

My concern is, as this will be a "mechanical" ignition systen running no ecu, Will it even work as is, or do we need to swap the dizzy shaft with the four points into the Cosmo CAS.

Best REgards
Kim
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Old Feb 1, 2014 | 04:49 PM
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From: https://www2.mazda.com/en/100th/
the CAS generates an AC voltage, so i don't think it will trigger the ignitor by itself.
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Old Feb 1, 2014 | 05:04 PM
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you would be better off using a 1st gen electronic distributor, you can even gut it to eliminate the cap and points firing if you want for the leading but for the trailing you would have to split the signal into two separate 180* increments somehow with an additional trigger so i leave the cap/rotor on and move the trailing coil inputs to fire through the old leading positions on the cap(basically the trailing ignition is nearly factory still).

you can then tie that into an MSD box to trigger a coil as an ignitor, by removing the J109 ignitors and using just the crank trigger circuit. ideally you only upgrade the leading to DLIDFIS and you can even leave the trailing somewhat unmodified since it requires an additional 2 MSD boxes for virtually almost no benefit on a complete upgrade.

using a crank angle sensor from a 2nd gen will eliminate any possible mechanical advance you will get from the 1st gen distributor, so a 2nd gen CAS will basically act as a "locked" distributor, which is fine if you can live with a locked timing figure.

the FD coils are also inferior compared to the cheaper and easier to attain FC coil packs.

Last edited by RotaryEvolution; Feb 1, 2014 at 05:12 PM.
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