472/500 fuel injection ?????

[Speach]

I have heard that some of the later 500 had this. Curious if it would be a beneficial swap/addition. Any thoughts on the pro's and cons of doing this.

[DaveM]

If the system is working right they are not bad.... But they can not be changed or reprogramed  , So they are best used on a stock low compression motor... If you want to run a aftermarket computer, like megsquirt or I use a haltech... They are not cheap , take a long time to get right...  With a aftermarket computer they can be set-up with any mods and any HP range... If you want to spend a lot of time and money I can tell you more...

[bcroe]

Its still possible to keep those old systems running.  The fuel handling components are pretty decent.  But
the system is completely open loop, and the electronics are incompatible with anything later.  Almost
everyone using parts from these systems, uses a much more up to date computer to run it, adding a
bunch of new features in the process (OX sensor, knock sensor, idle air motor, 3D ignition map, logging,
diagnostics, complex fuel-air maps, more...).  It is just barely possible to do minor tuning on the old ECU,
by changing parts, not by programming.  I did this to replace a 350 with a 403. 

There are a lot of threads on adding modern EFI using 76 500 or 77-79 425 parts, esp the GMC motor home
guys.  These are major projects, taking huge quantities of time and bucks.  good luck, Bruce Roe CLC @ 14630

[Speach]

Thanks guys. If I ever get one of those amazing tandem axle GMC motorhomes maybe I would consider tackling this. Too much for me. Those haltecc computers are for sure not cheap, I sold one for a friend used and it brought around a grand.

[blue68deville]

Affordable Fuel Injection shows a TBI kit for the 425/472/500 motors. Not sure which version ECU they are using, but they do offer a version with timing controlled by the ECU.

[c322348]

I have a complete stock Caddy fuel injection system I would sell if anyone is interested.

[Denise]

  Is it from a 425, or a 500, and how much do you want for it?  I can let my hearse club friends know about it.

[bcroe]

a "COMPLETE" stock system is a long list.  Includes in tank and in frame fuel pumps, fuel filter with mount to engine + tube,
intake manifold with 8 green or blue injectors + hold downs + fuel rails + 2 good temp sensors + pressure regulator + throttle
body with good cold idle air valve + special EGR controls + air cleaner spacer, fuel return tube, special HEI, 500 or 425 ECU,
and cables to above, battery, ignition, and starter.  Better add some documentation manuals and maybe my number to fix or
modify the ECU. 

good luck, Bruce Roe  CC # 14630

[DaveM]

I also have a bunch of those parts if someone needs something...

[c322348]

  Is it from a 425, or a 500, and how much do you want for it?  I can let my hearse club friends know about it.

I think it is from a 500, but not sure how to tell. I have the manifold with injectors, fuel pump and computer I think. If someone is interested I'll take pictures of everything.

[bcroe]

The injectors on a 500 are blue, 49 lb per hour.  The 425 has green-39 lb per hour.  I can look up
the ECU to identify the engine. 500s used a 160 8339, 160 8340, 160 8820, 160 8822, 160 8823,
160 8868, 161 1163, or 161 1491.     

Bruce Roe

[c322348]

Great info, thanks!