Greetings,
Really enjoyed reading both your project proposal as well as all of the follow-on
discussion by the ECU subject matter experts -- I've actually wondered about the
pros & cons & real-world feasibility of fabbing up a Q-Jet / 4L80-E hybrid that's good
enough to be a '
get to drive' instead of a '
have to sell' machine. Amazing
how many of my implementation questions were answered...even ones I hadn't
thought of yet on my own. :0)
Anyway, I'm not going to try to persuade you to convert the truck to
carburetion. Or, for that matter, attempt to persuade you to try to
grok EFI. Instead, I'd ask you to simply figure out which of the
2 different approaches will make
you actually look forward to opening
the hood (hopefully in preparation for a bucket list road trip) ...and
that
is the way to go.
****
Having said that, hypothetically speaking let's assume that you decide
to go ahead and return to Venturi-land. And that all the remaining
ECU <> 4L80-E details are properly sorted out.
So now we're down to choosing a carburetor that isn't just good enough
for a trailer queen or dedicated 1/4 mile racer. Instead, the carburetion is
good enough in the real world to be used for daily driving / carefree
cross-country touring.
Although I may be in the minority, IMHO the absolute best combination
of driveability, efficiency, and full-throttle operation is the Quadrajet.
More specifically, a Quadrajet that is carefully dialed in to
your powerplant
according to Doe Roe's book from the mid-'70s titled "Rochester Carburetors":
You must be registered for see images attach
I just checked, and even though this book has been out of print for ages,
there are currently copies of this book for sale, from rough to NOS condition,
for ~$12 & up.
IF you decide to run a Q-Jet and don't already have this in your
shop library, do yourself a favor & pick up a copy.
FWIW, Doug Roe worked at GM's AZ proving grounds, and was also a
motorsports competitor, especially in hillclimbs. His knowledge of how to tune
these carbs to the specific needs of a particular build is encyclopedic.
NOTE: Many people don't realize that the part-throttle driveability of a carb
is determined mainly by the
strength of the venturi signal obtained from the
air being ingested into the engine. In the case of the Q-Jet, not only are
the primaries small (high velocity airflow) but they are also stuffed with a triple
venturi setup. Jetted up properly, this design quickly responds to the slightest
change in throttle position. (near-zero lag)
NOTE: The only other carb I can think of that comes close to the throttle
response of a modern EFI setup is the Holley 4180 4-bbl that was used
on the '83-'85 Ford 5.0 HO motors. The biggest difference between this
carb vs it's 4160 ancestor was the use of the large annular discharge venturi
in the primaries. The main justification was more precise metering for
lower emissions (again, due to a much stronger venturi signal) ...but the
side effect was improved throttle response/driveability. As a matter of fact,
my first new car was a '84.5 Mustang GT with the 5.0/5-spd, and it drove
EFI good -- made for an entertaining daily driver!
Last but not least, the sound of a Quadrajet at WOT on top of a sharp
350 or 454 (preferably with air cleaner lid flipped) *still* gives me
goosebumps. If everything else technically came up even, the siren song of
the old Q-Jet at full throat would tip the scales for yours truly in favor
of the old school solution.
Good thing we aren't neighbors...I got a feeling that some dumb stuff
would commence in short order. :0)
From one old dude to another best of luck with whatever you brew up!
