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Message
That
does seem strange that the smaller injectors produce the same idle results. Are you 100% sure that those are the
injectors that are running at low speed ? Maybe the primary and secondary are
reversed ?
I'm about 99% sure it's running on the correct injectors, but I've also
turned off the primary switch, and run on the secondaries. It has
always idles slightly better on the MSD injectors, perhaps because they
behave leaner for some
reason.
With the 550 turbo injectors as primary, and 525 MSD injectors as
secondary, switching between the two at low throttle requires about 180
degree turn of the mixture knob. In other words, say I'm running on
the 550 Mazda injectors, and the mixture is set to 12:00. If I turn off
the primary injector switch, I'm now running on the MSD injectors, and the
mixture is way lean. I have to turn the mixture knob to the CW limit to
get back to about the same mixture that I had at 12:00 with Mazda
injectors. When I had
larger primaries than secondaries, I could at least imagine that's why the
secondaries seemed leaner. The baffling part is that this
behavior is unchanged with the new injectors. In other words, the
primaries are now smaller (460) than the secondaries (525), but the
secondaries still seem to be much
leaner.
I'll probably order the new plastic diverter thingies that go in the
block, so I can install the '88 NA square plug injectors as
primaries. I don't suspect that will change anything mixture-wise
though. I sure wish I could install the MSD injectors in the block,
and I may have to look at that again.
Also how
is the fuel pressure ? If it is too
high, maybe it is running very rich on both the large and small injectors. Does you fuel regulator have a MAP
reference so that it reduces fuel pressure at lower power settings ?
The fuel pressure is
42 psi when the engine is not running, and the regulator does have a MAP
reference. I've never really watched it while running to see if it
changed though. I just scribbled that on my note for
today.
My
engine is now running pretty good and idles very well at 1000 RPMs. My only rough spot is somewhere around
1500, it stumbles occasionally.
Mainly when the engine is hot. Now if I could just get my
temperatures down another 15 degrees I’d have it
made.
Pity I can't trade you 15 degrees for
a better idle :-)
Hey Tracy, how well does your engine idle
below 1500? Porting the engine should have some effect on the idle
quality, and since Bruce ported both of our engines, I would suspect
they'll be the same. Also, is anyone with a ported engine getting good
idle at 1000 or less? I can live with 1500, especially when I go
to the 2.85 gear drive. The bigger problem now is that I can't get
the B controller to idle at even
1500.
Cheers,
Rusty (FD goes on Auto Trader this
week)
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