This page was developed to help trouble shoot any possible problems and provide helpful technical tips for the products we sell. The following trouble shooting tips will cover the most common problems that can be encountered with our distributor systems. Also provided are answers to our most frequently asked questions. If you have purchased one of our products and encounter a problem not covered here, please call 901-396-5782 or email us at info@performancedistributors.com for further technical assistance.
Problems with irregular distributor gear wear can be caused by the distributor being "bottomed" out on the oil pump or cam walk. This problem can be easily prevented if the proper precautions are used. First, we will cover the problem with "bottoming" the distributor. Bottoming of the distributor usually occurs when engine work such as the block, heads and intake have been milled. This will allow the distributor to sit farther down in the engine. The best method for checking the distributor to find out if it is bottomed, drop the distributor in the engine with no gasket. Also, make sure the cap and rotor have been removed for this test.
Firmly hold the distributor against the intake with one hand and with the other, pull on the top plate of the main shaft. Very Important! Make sure you grab the top plate where the weights and center cam are riding. Do Not grab the reluctor (the part the rotor attaches to) because this part has up and down movement at all times. By grabbing the top plate you are checking for any up and down play in the shaft. If the shaft has up and down movement, you are now ready to install the distributor permanantly by adding the gasket and installing your hold-down clamp. If there is no up and down movement in the shaft, then the distributor is bottomed on the oil pump.
You will need to add a nylon distributor shim of correct thickness until the up and down play is achieved. Nylon distributor shims are available from Performance Distributors in thicknesses of .030", .060" and .100". When the correct shim has been determined, add the gasket and proceed with the final installation. Always use a gasket with the shims. Warning! Do not stack gaskets in an attempt to raise the distributor height on the intake. Gaskets will compress and the distributor will eventually bottom out. Always use a shim when necessary.
Another method of checking for bottoming, is applying machinists dye to the distributor gear. Spin the engine by hand several rotations. Remove the distributor and inspect the wear pattern. You should have an even pattern through the middle of the gear. If this is not the case, add distributor shims until the correct pattern is obtained.
If you have checked the distributor for bottoming and you are still experiencing irregular gear wear, then the problem could be "cam walk" or "cam run-out". This condition is where the cam is moving back and forth as the engine is running. Use of a cam button will help prevent "cam walk" but is not very effective if you are using a stock timing chain cover. The stock timing chain cover is made of tin and flexes easily, which can allow the cam to move even with a cam button. Use an aftermarket steel or aluminum timing chain cover that is reinforced for extreme cam loads. This should solve any problems with "cam walk".
Excessive distributor gear wear can be a problem with Ford engines. Most of the time, the problem is a result from the use of a high volume oil pump. High volume oil pumps put a lot of stress on the distributor and cam gears. A high volume oil pump is not necessary on a street driven engine that turns no more than 7000 rpms. Only extreme racing engines require the high volume pump. Should you use this type of oil pump, the following precautions will save your distributor gear from early destruction.
(1) Drill a .030" hole in the lifter/oil galley plug behind the distributor. This will allow additional lubrication on the distributor and cam gears. This will not lower oil pressure enough to hurt the engine.
(2) Ford oil pump mounting brackets have elongated holes. Due to this, the distributor shaft and oil pump shaft should be aligned so that the distributor turns freely before tightening the mounting bracket bolts. Failure to do this will cause a binding situation, thus damaging the gear.
(3) Stock Ford hex oil pump drive shafts are know to vary in length which could cause a bottoming or binding situation.
(4) Brass distributor gears can be used to avoid damaging the cam gear. Brass gears are softer and can wear out quicker than the cast gear, but will not cause damage to the cam gear. If using a brass gear, check it occasionally for wear.
If you are having a problem with the distributor not producing a spark, then follow these steps to help determine the problem. First and foremost, check to make sure your hot wire has 12 volts going into the distributor. Your hot wire must be at least 12 gage and have no resistors inline. Also, check to make sure all your grounds are good. A bad ground will keep the distributor from firing. If the hot wire and ground checks good then the problem could be with one of the electronic components inside the distributor. The distributor has three electronic parts which make it fire. The magnetic pick up coil, the module and the coil.
The magnetic pick up coil is located inside the distributor underneath the rotor and weight and spring assembly. It has a white and green wire coming out of it that plugs into the module with a yellow plastic insulator. The magnetic pick up coil can be tested using an ohm meter. With the green and white wires disconnected from the module, touch the meter leads to the terminals of these wires. The reading should be between 800-900 ohms. A normal reading is about 830-850. But as long as it is within the 800-900 range then the part is good.
The coil (in the cap) can be tested with an ohm meter as well. The resistance values for the coil are as follows. To check the primary side of the coil, touch the meter leads to the red and yellow wires. The reading should fall between 0.3-1.0 ohm. Usually 0.6 - 0.9 ohms is normal. Note that the red wire is positive (+) and yellow is negative (-). To check the secondary side of the coil, it must be removed from the cap. Touch one lead to the center black wire and the other to the bottom of the coil where the rotor bushing makes contact. This reading should be between 6.00K-30.00K ohms. The normal reading is about 8.5K - 9.0K for our Street/Strip coil. Refer to illustration 1 for proper testing of the primary and secondary resistance of the coil.
For the module, there is no resistance check that you can perform to see if it is good or bad. If you suspect the module is bad, you can replace it with another module to see if this will get the distributor to fire. A stock GM module can be used for this test. Or you could take the module to an auto parts store such as Auto Zone or NAPA and have them test it. It is recommended to have the test procedure performed 4-5 times. Reason is, each time the module is tested it develops more heat and heat is a major factor in the breakdown of the module.
Oil in the top of the distributor housing around the pick up coil and module is caused by too much crankcase pressure. The distributor does not suck oil up into itself. The shaft and gear only rotate, they do not force oil upward into the housing. The crankcase pressure forces the oil up into the distributor. The best way to eliminate the oil problem is to vent both sides of the engine. Moroso and Canton Racing Products both make a crossover tube with two beathers that allow you to breathe both sides of the engine. This crossover tube will not allow oil to splash out on the right side of the engine.
Another procedure to help alleviate the oil problem is to drill two oil relief holes in the distributor housing. First, remove the roll pin from the gear and remove the gear from the shaft. Be careful not to lose the shims and tang washer that are between the gear and housing. With the cap and rotor off, remove the shaft from the housing. On the housing itself, drill a 1/4" hole into one side about 2" up from the bottom of the housing. Do not drill all the way through, just to the center and back out. Make sure you drill above the two rings at the bottom of the housing. These are oil bosses and you do not want to drill into them. On the opposite side of where you drilled the first hole (180 degrees), drill another 1/4" hole about 1" underneath the flange that rests on the intake (where the hold down clamp is attached). Again, do not drill through to the other side, just to the center and then back out. These two holes will allow the oil to drain back down into the engine and will not hurt the strength of the housing.
One last procedure we recommend that is very effective and probably the easiest to perform is to fill four of the five slots around the bottom bushing with RTV silicone. The RTV silicone will stop most of the oil thats being blown past the bushing from going to the top. Leaving one of the slots open will allow the bushing to receive enough oil to prevent any damage to the shaft or bushing itself. To perform this procedure you will need to remove the distributor gear by knocking out the roll pin. Once you remove the gear, keep all of the shims and tang washer together. Remove the main shaft. Use an RTV silicone (available at any auto parts store) to fill in four of the 5 slots around the bushing. The illustration to the left has the arrows pointing to the areas that need the silicone. Allow the silicone to dry completely before reassembling the distributor. Once dry, install the shaft and put the tang washer and shims back on in the order they were removed. Reinstall the distributor gear and you are ready to go racing!
If you are installing a DUI distributor into an engine that has an ignition system presently, then this simple procedure will have your engine running in no time. On the old distributor, remove the distributor cap and the vacuum advance hose. Note the position of the rotor. We suggest cranking the engine over until the rotor faces the firewall and mark it with chalk. Remove the distributor hold-down clamp and bolt. Pull the distributor up and out of the engine noting the postion of the rotor as the distributor clears the engine. With the cap off of the new DUI distributor, position the rotor to where it was when the distributor was just removed from the engine. Slide the distributor down into the engine. Be sure the rotor turns back to the original position (mark on firewall).
If the oil pump drive does not engage, check that the rotor is pointing in the correct direction. If not, repeat the installation procedure. If it still doesn't engage, bump the engine over until the distributor drive drops into the oil pump drive. Reinstall the hold-down clamp and bolt finger tight. Install the distributor cap and transfer the plug wires. It is recommended to open the plug gaps up to .055" and this would be a good time to change them.
We recommend setting your initial timing at 12 degrees BTDC while the engine is idleing very slow (+ or - 600 RPM) and with the vacuum advance disconnected and the vacuum hose plugged.
If you are starting fresh and installing a DUI Distributor in a new or rebuilt engine, then you will need to bring the number one cylinder up to top dead center (TDC) on the compression stroke. Note: Make sure you are on the compression stroke or you will be 180 degrees out on the timing. If necessary, have someone spin the engine over while holding your thumb over the number one spark plug hole until you feel it "blow", and this will be your compression stroke. Turn the engine by hand to line the timing mark up to 0 on the balancer. Once this is established, drop the distributor in the block (without the cap) and point the rotor toward the terminal you want to designate as number one. Once the distributor is installed and all clearances have been checked (see Topic 1), re-install the cap. Now, add the spark plug wires and follow the firing order starting with the terminal that was designated as number one. For optimum performance, set the spark plug gaps at .050" - .055". Leave the vacuum advance disconnected and plug the vacuum line. Your engine should now be ready to start. Crank the engine and adjust the distributor until it fires. Once the engine is runnning adjust the initial timing to about 10-12 degrees before top dead center (BTDC) while it is idleing at 750 rpms or less. Once initial timing is set, lock the distributor down and recheck the timing. Plug in the vacuum line and go for a road test. Make sure there is no pinging under hard acceleration. If pinging is detected, retard the timing until it is eliminated.
