Tuning - Fuel vs. Spark, questions

[Bruce Plecan]

How do you know when it's time to start tweaking the spark advance instead
of fuel?   Under light acceleration (1600-1800, 65-75kpa range) I can't
tell if I should be tweaking fuel or timing - BLM's are around 120-123, but
it doesn't pull smoothly.

This area can test your will to live, least the first couple times getting
thru it.
There are just some cars that drive ya crazy in this area, too.
Kinda helps if you have some shallow grade hills.
*Generally*  I'll try working things out initally on flat land, and then the
small grades to finalise how much and how fast I pull the timing out from
cruise toward WOT.
If you have 128s at light cruise, then you know your at least right there,
so start adding fuel in that 60 to 80 K/Pa area.  You have to reach to other
side of the problem area often, so as the engine transistions to these
areas, the ecm is interpulating the fuel as it goes.  Like I mentioned in
tuning sometimes best to be at the low side of 128s so that their is a
slight excess of fuel available for that light tip in without using the AE
stuff.
Assumiing your cruise timing is like 34d at 40 Kpa, then just ramp it down
progressively to 20 at 100Kpa, in even steps.

BLM's at cruise are right at the magic 127-128.
Also, why in WinBin are the columns for fuel at 1600rpm so different from
the lower and upper tables?

Upper lower?
Open throttle vs closed?.
What address area ya talking about?
Bruce

-> Bob Valentine
-> bob at tecmark.com

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