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1916 - 1936

1928 Chevrolet AB Canopy Express

Discussing issues specific to the pre-1937 trucks.

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#130569 Thu Dec 06 2001 02:43 PM
Been thinking about all the stuff you can do to warm up a six cylinder. Does anybody know how the FI systems work on later model Chevy cars and trucks? The injectors . . . are they just solenoid valves that open when you hit them with 12Volts? Are they digital (on/off)and fuel delivery is a function of duration or are they analog (low voltage = low flow / High voltage = high flow and fuel delivery is a function of voltage)

I have a couple of surplus DSP controllers laying around and have been thinking about putting together an engine management system. What about crank / cam position sensors? Or should I put something on the distributor shaft? Just thinking out loud.

Also, while I am at it, is there any advantage to phasing the cam while running? Wish these old sixes had a separate intake and exhaust cam so you could phase them separately.

Anyway, just wondering if any of you guys have some input here. I have gone through the calcs on timing and it wouldn't be that tough to fire injectors as a function of shaft position and be able to tweak timing and duration on the fly.

#130570 Thu Dec 06 2001 03:31 PM
Joined: Oct 2000
Posts: 804
Shop Shark
Clifford research (the 6=8 people) has a fuel injection for the Chevy six in their catalog. smile

1948 Chevy Pickup
Chopped and sectioned
owned since 1974 when I was 15.
#130571 Thu Dec 06 2001 06:10 PM
Joined: Jan 2000
Posts: 1,609
Extreme Gabster
Ken, I know that GM throttle body injectors pulse on and off. To deliver more fuel, the pulse on rate is increased.Obivously, the the vehicle's computer controls the rate through feed back from the various sensors.I'm pretty sure that sequential port injectors work on the same principle.The port injectors are not timed to the individual cylinders like the older mechanical fuel injection or Diesel injection.They just spray in order in a constant cycle. Holley makes programable throttle body injection systems with an ECM and sensors.I think to get the system up and running properly, you would need dynometer time to map out fuel curves for street use.Adapting a GM throttle body is tough since, the stock system has limited adjustment.Maybe if the engine you want to use the system on is a similar capacity and tuning to a known GM engine ,you may be able to adapt it. Like using a 4.3 complete system on a 261 engine etc.The hardest part would be setting up a speedometer speed sensor on an older vehicle.I bet some one out there has done it.But would it work better than well sorted carburation, considering the time and money spent.

[ 12-06-2001: Message edited by: Tony ]

#130572 Fri Dec 07 2001 08:03 AM
Joined: Feb 2000
Posts: 4,655
I don't know much about this, but why can't you take a system from a engine of the same size and adapt? It seems to me the injectors or computor wouldn't know the difference. The mechanical part of adapting shouldn't be to hard. The timing could run off of the crank, I have seen 5HP B&S with crank trigger timing. The rest of the sensors could be mount easy enough. Its going to take somebody with a understanding of the computor to make it work. Just think how cool it would be! New hood emblems
" 261 L6 FI " !!! Joe

#130573 Fri Dec 07 2001 12:00 PM
Joined: Jan 2001
Posts: 667
Shop Shark
This may help

[ 12-07-2001: Message edited by: chuckthetruck ]

#130574 Sat Dec 08 2001 01:20 AM
Joined: Nov 2001
Posts: 72
Might try some of the F**d guys have been using it on OZ engines. The advantage is that you can make adjustments on the fly and don't have to have a laptop to do it. Also it is relatively inexpensive compared to some of the other stuff.
I was OK but I got over it.

#130575 Sat Dec 08 2001 05:38 PM
Dabond . . . great site! These guys seem to have a much better approach than what I have seen on other sites. An injection system on a 292 with a T-bird supercharger . . . hmmmmmm

#130576 Sun Dec 09 2001 02:17 AM
Joined: Nov 2001
Posts: 72
The only problem I see with the GM 6's is the siamesed intake port. That could probably be overcome with a port divider. F**d made it easier with their 300 6. As a side note my neightbor came into a treasure trove of Crosley motors. We were looking at them today and although they have siamesed ports, they could be port divided, and the head/cylinders are in one casting. If we could come up with some injector nozzles small enough ( only 45 CI) and turbocharge one of these ( 7 to 1 stock compression) we thought about building a belly tank or something and going to Bonneville. Probably a pipe dream but WTH it's fun.
I was OK but I got over it.

#130577 Sun Dec 09 2001 05:09 AM
I have read about folks who have put dividers in the runners leading up to the port. Or I guess you could do 3 injectors and just run them with the pair of signals associated with the two runners. If the controller doesn't like it, all you would have to do is put a flyback diode in each of the signal wires and it would never be the wiser.

#130578 Sun Dec 09 2001 06:06 AM
Joined: Nov 2001
Posts: 72
From what I,ve read you want to point the injector at the intake valve. If you put port dividers in that wouldn't be a problem, but you would have extend the dividers out of the port enough to get past the injectors. The port injection injection isn't exactly a precise injection like a diesel. Therefore you almost have to have the ports divided to keep the mixture right.
From what I've read and experienced on these things it gets worse if you have much overlap in the cam. Probably the best bet on the Chevys is to use a throttle body setup, but then you get back into the management problem. Well everyone said Stovebolts were easy.

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