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Installation Home

TBI Electronic Distributor Conversion
with Instructional Video

For Throttle Body Injection operation, it is necessary to convert the point style distributor to an electronic unit.  This can be done via one of the two options that follow. In addition to the distributor conversion, you'll need to upgrade your coil to one of the ones listed below.

Option 1 (Preferred Method) -  Lucas Conversion Kit from Patton Machine

These instructions cover an original Lucas distributor conversion to electronic operation with timing controlled by the ECM. This is the preferred method as it will provide complete ECM control and ignition mapping for you car.

Look over the following procedure and if you aren't confident doing it yourself, I will gladly do the modification for you. The cost for the Lucas distributor kit is $124.99. If you would like me to do the conversion for you, send me your distributor and the cost will be an additional $50.00 plus return shipping costs.

For a fully functional TBI system your original Lucas distributor needs to be converted from a contact point type to electronic. The magnetic pick up assembly provides a steady timing signal to the ECM to monitor engine RPM. For use with the TBI conversion, both the vacuum and mechanical advance will be disabled. What we are about to do can be reversed should you ever decide to go back to original equipment, not that you ever would.

In addition to the instructions below there are two videos at the vey bottom of this page.

With the engine at Top Dead Center, remove the distributor cap. Make note of the rotor's position (should be pointing toward #1 plug wire); do not turn the engine until the distributor has been reinstalled. Working on a bench with a vise makes things much easier. If you have a mechanical tachometer remove the cable by loosening the knurled nut on the side of the distributor. The wires need to be labeled and disconnected. Remove the bolt from hold down clamp at the base of the distributor. Pull out the distributor with a twisting motion. Lightly clamp the bottom section of the distributor shaft in a vise.
To remove the breaker point plate you will need a small Phillips screwdriver for the two little screws on the plate. After removing the two little screws, swing the plate up and over the center post pivoting on the spring linkage of the vacuum advance. Reach in with a small flat blade screwdriver and slip the vacuum spring linkage off the post. You should now have the breaker plate in hand.
Grab the upper portion of the shaft with the cam lobes and see if it will rotate slightly on the shaft. This rotation is controlled by the weights down inside the housing. Now remove the screw in the center of the shaft with a flat blade screwdriver. Does the shaft lift slightly before the springs get tight? If not, the two shafts are probably rusted together. Free up these parts using a combination of penetrating oils and perhaps gentle heat, (be careful as the tach drive gear is plastic).
If the shafts are free to rotate, using a small flat blade screwdriver reach down inside and disconnect the two springs. Careful not to harm the springs if you may someday want to restore the distributor to original specs. With the springs disconnected the upper shaft will simply lift out. The weights are no longer used so set them aside.
The removed upper shaft will look like the photo.
Shown here is the new shaft and reluctor assembly. It is a precise fit onto the spring posts. NOTE: IT IS DIRECTIONAL AND WILL ONLY FIT WHEN ALIGNED PROPERLY! You may need to rotate the assembly 180 degrees for proper alignment.
It should be a sliding fit with the spring posts sticking up roughly 1/4" above the plate. If the fit is too tight due to variances in the spring posts you may need to open the drive plate notches ever so slightly with a file. It's not time to actually install the shaft assembly now so set it aside.
 The distributor housing requires a slight adjustment to allow the pick up assembly sufficient clearance. The red arrow shows a stanchion that needs to be shortened by 1/4". The best tool I've found for the job is a Dremel tool with a 1/2" sanding drum. Grinding wheels should be avoided as they load up with the removed aluminum. A burr on a die grinder or even a moderate to high speed drill can also do a nice job.
Shown is the stanchion trimmed back. And yes it's a different distributor but the result is the same. Be sure to blow out the housing to remove the dust from grinding.
Shown here is the magnetic pick up mounted to a stainless plate. The red arrow highlights a screw used to adjust the air gap between the pick up and the ridges of the reluctor. To install this assembly first set the reluctor in place and engage it's drive plate over the pins. Then lift it slightly to slip the pick up assembly in place. Carefully tighten the two screws that hold the plate to the housing while rotating the distributor shaft checking there is no interference between the reluctor and the pick up. With the shaft assembly back in place install and tighten the screw in the recess at the top of the shaft. You may need to loosen the adjustment screw to increase the clearance.
 Looking good. The red arrow highlights the air gap between the reluctor and the pick up. It will vary a few thousandths as the distributor shaft is rotated. Using a feeler gauge set the width of the smallest gap to 0.006" by loosening the adjustment screw and pivoting the pick up. Carefully tighten and recheck the air gap. If you can't get sufficient clearance it may be necessary to remove a bit more material from the housing as you did when trimming the stanchion. Before reinstalling the distributor put the rotor on and snap the dist cap on. Again turn the dist shaft by hand and check that there is no binding or rubbing. Install your new electronic distributor!
The red wire from the pick up goes to the spade on the module marked "N". The black goes to the spade marked "P". If you are connecting to an AFI harness it's black to black and red to clear.

Coils suitable for use with the TBI conversion using the converted distributor and ignition module that is part of the kit. See Pertronix note below

NAPA coil # MPE IC88SB

MSD Blaster coils 8200 or 8203

Pertronix 40001, 40011, or 40111

Crane PS20 or PS40

NOTE: It's always a good idea to have a fire extinguisher handy when starting the car for the first few times. Turn on the key and you'll hear the fuel pump run and then stop. Check for leaks at all fuel line connections.

Setting the timing while still running on carbs:

You can run the car using the electronic distributor while still running on carburetors. To set the timing make the connections to the module BUT first disconnect the single pin connector near the module. Loosen the distributor locking clamp so it can be rotated with a little bit of friction. Position the distributor approximately in the same position as it was before the conversion. The cap and plug wires should be installed as originally. Connect a timing light to "1" spark plug. Be careful as the engine is able to start when cranking in this condition. Matter of fact once the timing is set it will run nicely on the carbs. While cranking the engine on the starter or at idle, set the timing to 14 degrees before top dead center. Lock the distributor down. If the ECM is installed and powered, you can connect the single pin connector which will allow the ECM to control timing even though the fuel injectors have not yet been installed.

Setting the timing when running fuel injection:

If the engine has been running with the converted distributor on carburetors (directions above) it requires no further adjustment.

Much the same as "Setting the timing while still running on carbs" but you will set the timing while the engine is spun over by the starter.

IMPORTANT: DISABLE THE FUEL PUMP OR DISCONNECT THE INJECTORS WHEN SETTING THE TIMING FOR FUEL INJECTION OPERATION! We're NOT trying to start the car yet. We just going to set the timing by cranking the engine.

If the engine has not yet run on the converted distributor a backfire is possible so disabling the fuel supply will allow timing to be set safely.  Disconnect the single wire connector near the ignition module. Using a timing light while cranking the motor with the starter rotate the distributor until the timing is set to 14 degrees. If you don't have a remote starter switch, you'll need a helper to turn the key while you set the timing.

To complete the distributor installation, lock down the distributor and reconnect the single wire connector. Make sure you enable the injectors or fuel pump that you previously disabled.  Providing the ECM is connected to it's sensors and powered up, you are now running a programmable computer controlled electronic ignition system! With a timing light you can check timing at various RPM's. For instance, just above idle speed, timing should jump out to about 20 degrees.

IMPORTANT: When driving if you hear pinging the timing is probably too far advanced, drop it back a couple of degrees. Excessive pinging can damage the engine. From this point on the timing should not require further adjustment and, unless someone is really looking, the conversion is really hard to spot.

 Option 2 - installation of a Pertronix Ignitor Electronic Ignition

This aftermarket component is readily available and typically costs about $100. With this option you don't have the advantage of electronic ignition mapping as performed by the Engine Control Module (ECM). For that capability you'll need to install my conversion kit as detailed in Option 1 above.

Please follow their directions for setting the timing.
 

NOTE: If you are running a Pertronix ignition, please check with Pertronix for the proper coil noting that there are two models of Pertronix Ignitor. The original Ignitor as used with most British cars requires a coil or coil/ballast resistor combination of at least 1.5 ohms while the Ignitor II has current limiting abilities

The following two videos walk you through the conversion process for making your Lucas distributor an electronic distributor.

Here's Part 1 of 2
 
And....... Part 2 of 2
 

 

 

Patton Machine LLC - Custom Components for Classic Cars