[Gmecm] Adjusting 7730/$8D for larger cam

[JohnsHome]

I would suggest upping your idle timing a bit to see if that helps. (closed
throttle table L81FD-8209)
Removing about 40mV from the o2 constants may help as well.
They are at L8496 thru L8498 locations. Will get the smell of unburnt fuel
to get better as well.
Not knowing what cam you are running, although it sounds like its mid 220
range from the description I'm not sure what else to suggest. Hopefully you
are running a heated o2. If not, get one for sure.
Idle will probably need to be around 700-800 rpm.
There is a hard code idle limiter in AUJP if that is what you are running.
It can be increased by changing BOTH values to be the same at locations
L426C & L4270.
these are in the code and will need to be added to your XDF or just done in
the hex editor.
They are single byte, RPM = 6400/255 = 25 rpm increments.
For 1000 RPM max idle you would use a value of $50
These have helped me out with my 224/230 roller 350. My idle is at 58Kpa @
800 RPM.
HTH
John

> -----Original Message-----
> From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org]On
> Behalf Of Clair Davis
> Sent: Thursday, February 01, 2007 9:20 PM
> To: For discussion of GM EFI hardware and software
> Subject: [Gmecm] Adjusting 7730/$8D for larger cam
>
>
> Now that my engine is running pretty reasonably, it's apparent
> that it's PIG
> RICH at idle. I'm about 99% sure this is due to the
> lower-than-I-hoped idle
> vacuum reading. When running with a carb, this engine managed about 13-14"
> of vacuum (44-47kPa if I'm doing the conversion right), now it's 10-12"
> (34-40kPa). The tune I received from my chip supplier supposedly
> wanted 15"
> at idle (51kPa). Since I'm not reaching this level, even after
> advancing the
> cam 2*, I think I need to change my idle vacuum level.
>
> Going through TPRT, it doesn't appear that this is any kind of one-point
> setting, and is probably in the tables. Is it reasonable to
> adjust the table
> points on the idle end down to where I need them? It might be that I get
> better vacuum if the mixture is leaner, but I'm thinking that the rich mix
> is due to the apparent load on the engine, not a quirk in the VE table
> (yet).
>
> Any wisdom would be greatly appreciated...
>
> Clair
> _________________
> 67 Cuda Vert (?/833)
> 68 Sport Fury Vert (NOM 440/727)
> 69 Valiant 100 (340/833/7730EFI)
> 74 Dart Swinger (440/727)
>
>
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