[T3] Giving up Stock FI

[Phil Hof]

Regarding gas mileage, my ’71 with almost-stock D-Jet gets about 25 in normal use, which includes short (5mile) trips to work, errands in town, and occasional cruises to the coast.  On the last couple of highway/freeway cruises (Cost Rally and Meet in the Middle) it was more like 30-32.

My setup is a 1776 with larger injectors, and tuned a few years ago using a F/A meter with the sensor right at the neck of the resonator where it clamps to the main muffler body.  Now that it’s broken in, and after I rebuild my distributor, I’ll probably recalibrate the MPS and do a few tweaks to smooth transitions and improve the in-town mpg a little.

What’s interesting, is that this difference of maybe 20-25% between highway and town driving is much larger than it used to be.  When the car was pretty new, and stock, it didn’t really matter how I drove.  I could feather-foot it, and get maybe 33-34; if I lead-footed it, it would still rarely drop under 30, more like a 10% band.  I attributed this to the FI, which would seek to have the right A/F mixture better even under widely varying loads.  So either that was a myth, or i need to lean out mine a little under power and transitions.  I figure I’m a little rich on acceleration, but pretty good on cruise.

-Phil