In adding any EFI system, it should be remembered that it is only a fuel/air mixing mechanism, just as carburetors are. Except the EFI system can usually get better atomization of the fuel droplets as it does its thing. NO massive amounts of horsepower increases, either.
Even with the Throttle Body Injection types, what WILL be noticed is better drivability (as it is computer controlled), especially when cold. That was my impression from the first OEM GM 2bbl TBI systems in 1987.
Reason? In a carburetor, open the throttle plates, more airflow due to intake manifold vacuum. More air flow through the venturis pulls more fuel out of the float bowl as needed. If everything is working well, no real lag results in getting fuel into the engine that way. Worked for ages.
With electronic EFI, as soon as the throttle position sensor is moved one nano-degree, additional fuel is put into the engine THEN, not later. Result is much better throttle response and perceived power. With the better fuel spray pattern from the TBI injectors, fuel economy CAN increase, too, but this can be variable as to driving style (i.e., how steady the driver keeps the accel pedal, rather than constantly moving it!). Of course, how much enrichment comes from such movements is a part of the OEM and aftermarket programming!
On the then new 5.7L 1/2-ton pickups, when people got into them (after driving a 305 4bbl), they immediately smiled as to the additional power and throttle response ("This thing runs GREAT!"), but at the free 3000 mile oil change, they were complaining about fuel economy. "Driving style".
On the new '87 5.7L pickup I had as a company truck, driven mostly on freeways with a bit of surface streets . . . I was asked to log my mpg for several tanks of gas, which I did. It was 55mph for the national speed limit back then. Driving conservatively and cruising at 55-60mph, I logged several tanks at 19.5-20mph average! 5.7L, THM700 OD automatic, 3.08 gears, P235/75R-15 factory radials. Consistent "fill levels" at refueling stops, from the same gas pump. 87 Pump Octane fuel. a/c working, too.
Now, after getting those results, I was totally amazed. Considering the '78 1/2-ton I had with a 5.7L, THM700, with the only main spec differences being the QuadraJet and 3.42 axle ratio. The best mpg that truck did was 13.25mpg average on its first full tank, when new. Then settling into about 11.5mpg after that. Which was not too much worse than the 7-8mpg 454 3/4 and 1-tons that were selling like hotcakes back then.
A few notable things, though. The '87 head castings had the cleanest intake ports of any GM head casting I had ever seen, to that time. The exh manifolds looked the same, but had larger passages and a larger exit hole, like 2.125" diameter rather than 1.875" or 2.00". The single exhaust system was better as to consistent pipe sizes, into and out of the single muffler, to the end of the tail pipe. ALL little things that helped.
You WILL need an electric fuel pump that can supply 55psi pressures, period. Either the external pump near the rear of the car or the "sump pump" in the engine compartment (which Edelbrock seemed to first use a while back), which can use the existing mechanical pump to supply the sump with, then an internal pump in the sump will elevate the pressures to what the EFI injectors need to work well. IF you have enough under hood real estate to mount the sump pump items!
ONE other thing pointed out in a Chevy TSB about 454 TBI engines. All of the total airflow into the engine will be at abt 90% at approx 75% of WOT. That was on a 2bbl TBI unit. NO "4bbl feel" going to WOT, either, when the secondaries were expected to kick in on a 4bbl.
I'm not sure if the throttle plate linkage on that new system is staged to have all four plates open at once, or if primaries first, then secondaries, as a normal 4bbl carb does.
In cases where the cam and intake ports are each too big, an electronic EFI TBI can somewhat tame that system where a well-finessed carb usually can't. Computer controls and such working their magic.
You will also need at least one, possibly two ganged together, oxygen sensors a specified distance past the front of the head pipes of the exhaust system. Getting those done is easier now with "no welding", bolt-on bungs to screw then into, by observation. Very possibly included in the basic install kit for the unit? Usually, the TBI is sold separately and the full install kit has the pump and a roll of high-pressure rubber fuel lines in it.
As MUCH as I might like and appreciate these aftermarket, add-on, self-learnign EFI systems, it can take a good while to get the purchase price of the unit (not counting any outside labor charges for installation!) saved in fuel savings alone. Which can make the annular discharge venturis of the Edelbrock AVS2 much more attractive (due to lower purchase costs and less installation complexity).
You can probably find all printed information on the system in the Edelbrock website. INCLUDING the installation instructions.
Edelbrock might not mention it, BUT for best results, you probably need to have a pair of cylinder heads with the modern "heart-shaped" combustion chamber for best combustion dynamics. Better combustion dynamics than stock Chrysler cyl heads, typically. On the other hand, a set of closed-chamber B/RB cyl heads might be a good "iron head" choice, too, due to all of their "squish" action not present in the 906-style open chamber head combustion chambers.
I'm NOT sure what your goals might be in getting the system? Bragging rights? Better mpg and throttle response? More total power? OR the size and performance level of the engine you desire to install the system on?
Hope this might help,
CBODY67
