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post #1 of (permalink) Old 05-31-2000, 06:44 PM
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Buick V6 Odd-fire fuel Injection works

Many experts in aftermarket fuel injection have said in the past that a Buick 225/231 odd-fire engine could not be fuel injected--even TBI (throttle Body injection) injected.
However, I have successfully done it with a crank shaft sensor that signals the injection computer(instead of the odd-fire distributor)
The engine is a 1975 231 Buick V6 odd-fire, a .50 inch over bored 225 engine (just like a Jeepster 225 V6)
I mounted the TBI unit using a home-made aluminum plate adapter to the 231's intake manifold . The TBI unit is off of a 1990 ChevyAstrovan. The TBI unit is a Rochester model 220 throttle body injection unit and is factory equipment on a 4.3 liter Chevy V6.
The ECU(computer is also from the same Astrovan).
The 4.3 Chevy V6 throttle body injector was designed to get a signal from the ignition system that tells the throttle body injectors to squirt
gasoline at when each spark plug fires. Buick odd-fire engines could not be run an electronic injection system by distributor pulses as a means of fueling the engine because the odd-fire pattern of the distributor confused the injection computer.
So to get around the odd-pulses of the odd-fire Buick V6, I mounted
a Holley Crank Trigger to my Buick V6's crank shaft and used the Crank Trigger's pulse to signal the computer though an ignition module.
The Crank Trigger provides an even 120 degee spaced pulse that triggers the injectors, and monitors the engine RPMs.

With the Help of Affordable Fuel Injection at http://www.affordable-injection.com --for the TBI and Harness , ignition module, the system was fired up this weekend--- it works! Affordable Fuel Injection (AFI) is a new small company that might decide to market a Buick V6 Odd-fire kit based on a crank sensor driven TBI unit. If you are interested visit their WWW site and send them an e-mail---

I will get together some pictures of the system and details in the near future.

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post #2 of (permalink) Old 05-31-2000, 07:19 PM
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Re: Buick V6 Odd-fire fuel Injection works

Awesome work! It is a shame that the so-called "experts" are taken for their word way too often. Looking forward to the pics!

On a side note: A few years ago I saw a documentary on someone developing an electronic valve system. Thus you could essentially change your valve timing at the push of a button. Super fuel efficiency until you meet up with someone at a stoplight. The ultimate in "sleeper" technology. I wish I knew who was developing the idea. Quite a project. Maybe when I get some time will play with a computer program for it.

post #3 of (permalink) Old 05-31-2000, 09:27 PM
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Re: Buick V6 Odd-fire fuel Injection works

I'd like to know what was used for the VSS (Vehicle Speed Sensor). I'm also wondering if the system is a "closed loop" system with an oxygen sensor.

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post #4 of (permalink) Old 05-31-2000, 09:34 PM
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Re: Buick V6 Odd-fire fuel Injection works

Congratulations SRR_Denver, you've done good. The GM TBI is probably the most reliable system out there.
Now I wonder where the best location would be for drilling the holes for PFI ----?

Re the electronic valve timing. Chrysler did quite a bit of work on it a few years ago. The Cadillac 4-6-8 system was along the same lines, sort of.

The Caddy used a solenoid to rotate a shaft that kept the intake valves closed, thus disabling cylinders. It ran on 4 at idle and light cruise, step on it a little, it went to 6, nail it, it went to 8 cylinders working. There were problems with it, the controls stuck, the solenoids broke etc. Eventually everyone just pulled the connectors loose on the valve covers, reverting it to normal 8 cylinders. It also had a tendency to catch on fire.

The Chrysler experimnents were awsome. They had individual solenoid driven valves. The computer could dial in most any valve timing it wanted, based on temp, load, RPM, and throttle position. From a very short duration to lots of overlap, ranging from economy to sheer power.
But, being electrical, pass a radio station, a CB set, or another car with a bad plug wire, any electrical interference, the valves would open at the wrong time - not all the time, just occasionally. But, once is enough to warrant new heads and pistons.
They were able to demonstrate what happens when a valve opens at the wrong time.
Someday it will be perfected and we'll see it, and it will be fantastic. But for now it's too unstable. Have you ever had your PC lock-up or do something strange? You can see why.

Another great invention that hasn't been used much but I think will be someday, is the pre-combustion chamber idea like some Hondas use.

Excuse me Bill, --- OK, OK, I know Microsoft says windows never crashes.

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post #5 of (permalink) Old 05-31-2000, 11:44 PM
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Re: Buick V6 Odd-fire fuel Injection works

Congrats Steve. You have been working this out for a while. I'm like Dave what input sensors are you using ?
Crank sensor. Temp sensor. O2 sensor. Are you using all the sensors from the original donor to allow the puder to go into "closed Loop"?
Congrats again.

Lenny in Colorado Springs
67 Jeepster 225 3 speed(building me a T18 now!!)
post #6 of (permalink) Old 06-01-2000, 12:21 AM
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Re: Buick V6 Odd-fire fuel Injection works

Nice work, let us know what it does for you, sounds great. I would be interested in the PFI system, but the rochester hums along for now, no complaints yet.

yes, my user name is a typo, go figure.
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post #7 of (permalink) Old 06-01-2000, 01:36 PM
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Re: Buick V6 Odd-fire fuel Injection works

Good work, Congratulation..

I would like to do TBI for my Jeepster..

Jeepsternut Duane

post #8 of (permalink) Old 06-01-2000, 01:37 PM
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Re: Buick V6 Odd-fire fuel Injection works

Good work, Congratulation..

I would like to do TBI for my Jeepster..

I wonder if you'll see an improvement in fuel economy...

Jeepsternut Duane

post #9 of (permalink) Old 06-01-2000, 02:48 PM
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Re: Buick V6 Odd-fire fuel Injection works

My Buick Odd-fire TBI is run by a closed loop system.

This breed of Fuel Injection is old by the most current fuel injection standards, being used on GM luxury cars in the 1980s and Chevy Pick up trucks and Vans in the early 90s.

But it offers many advantages to a 1960s era engine.

There are FIVE sensors involved in the system :

1) Crank Position Sensor a.k.a. Crank Trigger
The Crank sensor I adapted to the Buick Odd-fire is a Holley aftermarket device. It is composed of an aluminum wheel with three magnets in it that are spaced at 120 degrees around the wheel. This wheel with magnets is about 6 inches in diameter and bolts behind the crankshaft pully. A magnetic pickup is mounted on s bracket off of where the mechanical fuel pump once was mounted. The pick-up is adjusted .040 of an inch from the wheel and generates a micro voltage signal that the computer reads everytime a magnet passes by the pick-up point. This is needed by an odd-fire engine, but not for an even-fire Buick V6.
On the even-fire Buick V6 the distributor signal will work, but the odd-fire Buick V6 distributor signal is irregular and confuses the computer.
The Crank Trigger signal tells the computer when to tell the injectors to squirt gasoline-- and is one of the inputs that regulates how much gasoline enters the engine at various RPMS.

2) O2 sensor--
Mounted in one exhaust pipe, reads the amount of oxygen in the exhaust and is adjusted to maintain the gas to air mixture at about 14 to 1. The O2 sensor is a generic GM sensor.

3) MAP sensor--
The Manifold Absolute Pressure (MAP) sensor sends a signal to the computer to adjust gas to air mixture based on Intake manifold vacuum.

4) Throttle Position sensor (TPS)
Sends a voltage change to the computer as the throttle position changes-- runs mixture during open system (cold) operation, and acts like an accelerator pump squirter during closed system operation(engine warm)

5) Coolant Sensor
Tells the computer when the engine is warm enough to switch over to closed loop from open loop.

To tune the system I will first get a scanner and monitor the outputs of each sensor at various engine loads and RPMs-- and take notes. A new chip could be designed to specifically handle any special needs revealed by the scanning notes.

I am running a 1975 odd-fire vacuum controlled HEI

I am using an odd-fire engine because I like the way they run with a sentimental lump-lump-----lump-lump

The system I built is 100% usable on a Buick V6 even-fire 3.8 engine- so if I blew my odd-fire engine, I have a 1987 even-fire in the garage waiting to go as a possible replacement.

My vehicle ( 1983 Nissan 4x4 PU ) by law will have to run a closed loop system in order to be smog legal in Denver, Colorado.

One other good WWW on an older 4x4 vehicle getting TBI is found at ---

As long as your carburator runs good on your engine--- maybe just keep a carb...
You could buy a lot of gasoline for the price and effort of fuel injection. Changing
to an electronic fuel control system for me was a legal requirement imposed on me by
the legal powers that exist in the Denver Colorado Metro area.
Once upon a time I just swapped engines and away I went-- but that was when I lived in a non-smog controlled area of the

I am of the opinion that the odd-fire Buick V6 is worth rebuilding and running in a light 4x4 vehicle.
It has some high torque, light weight, and compact size properties worth preserving---and I love that
old Buick odd-fire Lumpy-lump rythum.

I will get some pics up on the www within a couple of weeks


post #10 of (permalink) Old 06-01-2000, 06:16 PM
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Re: Buick V6 Odd-fire fuel Injection works


How recent were these Chrysler experiments you are talking about? Do you remember any articles or books on the subject? Very interested. I dunno if a Windows machine would be necessary. Possibly get by with machine code without a gui.
I've never seen the Caddy864 in action, though I've read about there lack of reliability. Have worked on a 87? Honda CRX. Was wondering what those wacky valve things were for. They didn't work too good, leaked oil in cylinders real bad. I'm sure they have worked out the, or at least some, of the bugs by now.

neat stuff

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