Ford Distributor Gear Install
Depending on who writes the instructions, the method and the dimensions can be different, but in any case, the objective is to press the distributor gear on such that when the distributor gear bearing face is resting on it's mating surface in the block, the distributor shaft should be floating in the middle of it's free play. Regardless of instructions, the following method will ensure the gear is set up absolutely perfect
Process using a MSD distributor in a 351Windsor engine
1. Measure the depth of the bearing surface in the block 4.027 in this case
2. Measure the end play in the distributor .032" in this case. This dimension can vary, but .024"-.035" is considered in spec.
3. Using the bearing surface depth in step 1, add half of the free play measured in step 2. This will give you the maximum dimension to which the gear should be pressed on. In this case 4.043. Note in the photo below, the shaft is held to the right, or distributor base to the left so that it is at it's maximum length
4. To verify a proper press fit, install the distributor in the block, tighten it down and set a dial indicator to indicate the distributor shaft. Adjust the dial to zero
5. Lift the shaft to the end of it's end play and note the dial reading. Ideally it will read .016", but any dimension from .005 to .027 would be acceptable. This indicates that the distributor gear is riding on it's mating surface in the block and that is is not in bind.
When proper end play is verified, remove the distributor and install the roll pin through the gear and shaft.
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