RE: I finally took the leap - general tuning questions

["Jim Sloan" <leroy@sunflower.com>]

>
> I got back the first chip I had another lister burn from a
> bin I modified
> myself.  And it ran different in just the way I would expect,
> so i guess I
> have the modify thing figured out.

Congratulations Ryan!

> I also ordered everything
> I need from
> digikey, including a PB10, eraser, 27c512's, and some
> assorted adapter
> goodies.  I got tired of trying to get an old beater burner
> to work and
> waiting for a deal on EBAY.  (which I must say there are a
> lot under EPROM
> and TPI).  So I will soon be in the hunt.  I also have
> trouble firing a rich
> mixture at high cyl pressure, So i ordered the accell
> amp/coil apckage for 87

Did you try a narrower plug gap?

> up GM from naparts.com.  If no one has any comment about this
> IGN unit, I
> guess I will let you all know.  The crane unit looks like it
> did exactly the
> same thing for less bucks, but the website info said it was
> not waterproof
> and should be mounted inside.  Screw that!
>
> OK - in stock TBI 350 bins, there is a big dip in the fuel
> map aound about
> 4800 prm, and it comes back up around 5600.  This is exactly
> where my truck
> was slow with the howell bin, which turned out to be a stock
> bin only with
> too much advance and the idle turned up.  Why is this dip
> there?  I can
> understand that the stock application shifts at 4000 and
> shuts off at 4800,
> so why the dip.  Even if the VE of the engine starts dropping
> off as you run
> out of cam and into intake, head, exhaust restrictions, why
> does it the fuel
> curve take off again at 5000+.?  You could never get there,
> so what gives?

I wouldn't worry about it too much. Things change as you start making
modifications. Make the fuel map that works best for you.  Do some
performance testing and datalogging to make sure you're on the right track.

HTH,

Jim Sloan
leroy@sunflower.com

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