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  1. #23
    Fuel Injected! Willys43's Avatar
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    Quote Originally Posted by 1project2many View Post
    I learned that Maserati's approach to odd fire was to use dual coils connected to a single distributor. The 225 will likely never see the same RPM as the Maserati and will likely never have a dwell issue. But we have a solution should there be a need for 5k+ rpm revs in the old Willys.

    It appears the MS2 code can use an option bit for odd fire engines and a user entered value for "small angle" to help differentiate the pulses. However, this solution is not universal. Several posters on the msextra board used dual pickups in a single distributor and a special input mode in MS that took the input from the dual pickups. One poster even ran dual MS systems.

    GMECM's actually average the crank pulse signal some. It may be possible to rewrite the GM code so it will do the same. There are also changes needed to the dwell computation to account for small / large time variations. I suppose we could determine a window of time representing maximum possible engine acceleration and determine that any substantial change in time less than that window must represent the switch from "large" to "small." It would follow that the next pulse is a "small" to "large" transition. I really wish I had time to play with this stuff. It would be an interesting excercise.
    It's not even a 225, it's a 198 Fireball, just too damn cool to throw out. I checked my gear ratio chart and the highest RPM I used was 4000 to get 82 mph, which it will never see with this nut behind the wheel. I'm going to try to use two ign modules and 1 HEI coil and see if it will work. Do you think I'll have a dwell issue? I thought dwell was adjust in respect to fuel burn time in each Cyl rather than when the Cyl burns it(odd fire). The Odd fire HEI distributor didn't have any provision for adjusting the dwell,(outside of the initial setting). Please shed some light on this. While reading in the MsPro manual I found a very good explaination of IAC stepper motor operation, I understand the 4 wire system now.
    Last edited by Willys43; 04-19-2016 at 05:02 PM.

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