TR2/3/3A Installing the distributor pedestal.

[sp53]

Installing the distributor pedestal. I have read in the Haynes Manual how the end float of distributor drive shaft hidden in the pedestal is important and is achieved by using shims if necessary. Reading in Haynes books on page 52, they want a temporary washer that is 0.5 to help establish a temporary gap and adding shims if needed between the block and pedestal to maintain the gap for the shaft.

Is that 0.5 they want a typo because that is a ½ inch? I would think they wanted to say .05 which would be 1/20 of an inch and to me that sounds about right for a float distance. I have never set the distributor float on the engines I have rebuilt this way. I put them together with no shims because that is how the engine was running before I did the rebuild. I use the gaskets in a gasket kit to stop oil leaking between the block and pedestal and they probably hold the pedestal up the. 007 the book talk about for an end result and float and call it good.

I was hoping a member who is better at math than me could help out and see if my math is correct.

steve

 

[mastaphixa]

I believe the .5" figure is the inside diameter of the hole in the washer so it will slip onto the oil pump drive shaft. It doesn't matter how thick it is, but you need to measure the thickness. After placing the washer on the shaft and inserting it into the bushing and engaging the oil pump put the pedestal on and measure the gap. Lets say the washer you used was .060" thick. The gap between the pedestal and the block measures .056". That would indicate you have .004" of float. Make anymore sense? **WARNING, FIRST CUP OF COFFE MATH WAS INVOLVED"

 

[Popeye]

I just went through this on my TR4A:

Mastaphixia is correct: the half inch refers to the ID of the washer. Not critical; you just want something under the gear, to push it up, such that the pedestal firmly touches the top of the gear. (A 1/2" washer nicely fits on the oil pump drive shaft.)

It is important to measure the thickness of the washer. Note, washers may not be flat... I used the parallel flats of a caliper to find the thickest point (i.e. how much the gear will be pushed up).

Once the washer is under the gear, assemble the pedestal, torqueing the bolts per spec (8 ft-lb??), and measure the gap between pedestal and block using feeler gauges (I also measured with a caliper to confirm).

Then, as Mastaphixa described, the difference is the float. Float = thickness of washer - gap between pedestal and block. (0.004 = 0.060-0.056, in Mastaphixa's example)

For my engine, I was at the top of the spec without any gaskets / spacers (0.006 measured float, vs. a spec of 0.004-0.007). So I reassembled using only a thin layer of Permatex flexible sealant, but no spacers. (Following a recommendation by Randall on a previous post. Post #3: > Distributor Drive End Float <)

 

[Sarastro]

I know that the procedure seems odd, but the point is that you can't get into the distributor pedestal with a feeler gauge to measure the end float directly. So, you have to do the indirect measurement described in the shop manual.

The setting is important, because the shaft goes through the oil gallery on the side of the engine, allowing full oil pressure on the underside of the distributor drive gear. Too much end float and it could affect oil pressure. Of course, if there is any looseness in the structure it will result in irregular timing, and gears always must mesh properly for minimum wear.

When I did this, I made a washer, so it was perfectly flat. If you use an ordinary half-inch washer, you might want to polish it a bit on some sandpaper, laid on a flat surface, to take out any burrs or lip around its edges.