Cyl Select onna 747

[Bruce Plecan]

-----Original Message-----
From: Shannen Durphey <shannen at mcn.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Saturday, October 17, 1998 10:46 PM
Subject: Re: Cyl Select onna 747


>Bruce Plecan wrote:
>>
>> -----Original Message-----
>> From: Shannen Durphey <shannen at mcn.net>
>> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>> Date: Saturday, October 17, 1998 4:34 AM
>> Subject: Re: Cyl Select onna 747
>>
>> >> Well seems like someone had too much free time, so he set
>> >> the cyl sel on his 747, to 4 cyl.,and tried it in his 7.4L gm Pickup.
>> >> Was way rich but rpm read right, and drivibile.
>>
>
>>   I'd think that ECM would see
>> >extremely rapid RPM increase and advance timing too fast.
>>
>> Me and Doc are confused here.  Even spinning the tires with a
>> higher than stock stall converter has never been a problem.
>> I don't see where a rate of change, would be a problem.
>> Cheers
>> Bruce
>>
>>   That
>> >is, if rpm read 2x(right for 4 cyl).
>> >Shannen
>> >
>I said that wrong.
>
>If rpm reads double (4cyl), the ecm would see 2K rpm at 1k actual,
>timing advance would be for 2K rpm (not forgetting map, here).  No,
>rate of change makes no difference, but higher RPM+map would seem like
>less load and so more advance.  Limit would be in the calibration.

Yes, this is true.   But, this is just an initial diddle, and not meant to
be the final word.
  Just because we have a ALDL saying the ecm is seeing something, doesn't
mean the calculations are being applied right.
Cheers
Bruce
>
>Been playing with vacuum advance can and mech. springs tlast couple of
>days, you see.
>
>Shannen
>