I bought one the CRT tach drive distributors in Sept. I didn't install it till early Dec. It looked very well made and seem identical as far as the part that fit into the distributor. It is taller and I got the female type cap. When I road tested my Bird I was very impressed. has more power and ran fine. BUT after I came home and open the hood, I discover the distributor is wobbling a little! The hold down was tight, great, after market crap. Called the seller, too bad I had it too long. After lots of measuring I discovered that the drive gear seems to be is deeper on the shaft and is bottoming out against the block. I am going to space the distributor housing up-away from the block. I am pretty sure this will cure the problem. I am going to put it back in and see if I can put a feeler gauge between the block and the distributor. before I make some shims. I bought some thin metal stock from Hobby Lobby of all places,to make the shims. I'll let you guys know how this works. Ted said he has run into the same problem with FE engines and cured the problem by taking the pin out and drilling a new hole to reposition the gear. This problem does not seem to be that much difference, will see.

How far off are we talking about, if the gear is installed to low on the shaft it is holding the shaft up and it may not be completely engaging the oil pump drive shaft

Both Paul and Joe have ordered the CRT distributors.  Paul is having his dropped shipped to me and when I receive it, I’ll be measuring the gear location on the shaft to insure it’s not too low thus being in a bind within the engine I plan on testing it in.  As a general rule, the MSD distributors for the Y have the gear positioned on the high side so none of those have an interference problem within the block.  The gear being a little bit high is not a problem with the MSD distributors but being any shade of too low definitely is.  Before sending that CRT distributor back to Paul, I’ll have him measure the distributor cavity in his block to insure that his distributor is also good for his particular block.
 
Part of the problem with distributor gear placement lies in the block machining as not all the FYB blocks are at that 4.990”or more cavity depth for the distributors.  While most are okay, there are those blocks that are machined too shallow on the distributor hole and just being 0.025” less than 4.990” does create a problem with some distributors.  Hence the reasoning why MSD intentionally installs their gears on the high side for the FYB.  The easy fix is just shim the distributor where it sits on the block with a special shim so it’s raised the appropriate amount.  A fix that’s more involved is removing the gear and relocating it to the appropriate spot on the shaft that also coincides with what is needed at the block.
 
The Ford 351W engines seem to be more prone to the distributor holes in the block being too shallow thus creating premature wear problems when replacement distributors are used.  I’ve also come across this same problem with a 460 BBF block but that issue does not appear to be as common as what I find on the 351W engines.  The 460 BBF was fixed by just simply shimming the distributor higher.  All other engines I have corrected by just relocating the gear on the shaft which does involve drilling new hole for the pin that retains the gear to the shaft.

Lorena, Texas (South of Waco)

Interesting. It hadn’t occurred to me, but I should likely measure the gear location on the 50s NOS Mallory Dual Point that I bought on eBay before installing it.  Quality control & machining precision is something that probably couldn’t have been taken for granted 65 yrs. ago.

6 VOLTS/POS. GRD. NW INDIANA

I think they did better 65 years ago then the Chinese do today..

It will be very interesting to learn what Ted finds once he gets one of these on his operating table.  If it has, as I suspect, a ball bearing instead of a sleeve bearing, there may be little or no axial float thus binding when clamped down. Often ball bearings have "some" interference fit. Curious to know if the strib has at least minimum .022" up & down shaft movement and what the distance of the gear installation is? It should be 4.991 to 4.996" bottom of gear to underside of the mounting flange with shaft pushed downward if I'm remembering correctly. If someone has one not installed,, a caliper would provide a good indication. The new strib may be made too precision and therefore not compatible with the manufacturing tolerances of the 50's. Just a thought...............


64F100 57FAIRLANE500

Paul sent to me one of the new TSP distributors designed specifically for the ’55-’57 Thunderbirds.  The packaging on the supplied box says TSP and not CRT.  This distributor is mechanical tach capable.  The quality of the parts looks good and some careful measurements of the gear placement on the shaft found it to be 4.983” collapsed and 4.998” extended.  The specification within the 1957 Ford service manual calls for the collapsed measurement or pushed up dimension to be 4.991-4.996” with end play being 0.022-0.030”.  My experience has shown that the distributor hole measurement should fall anywhere between the extended and collapsed distributor gear measurements.  I measured the distributor hole depth in the 312 dyno mule and it is 4.990”.  That makes the new TSP distributor correct in its gear measurement as the gear will not be in a bind when installed in the block.
 
As a FYI, the MSD distributors do have their distributor gears placed higher on the shafts (reduced collapsed measurement) than what’s called for in the Ford manuals but after having dealt with a number of blocks that are machined on the shallow side (not deep enough), I can understand the reasoning for having the gears higher rather than lower on the shafts.  Having the gears not running on the distributor pad in the block is not an issue for the MSD distributors.  No major issues with the gear being on the high side but any gears that are too low can have some severe wear issues in that area.
  
The distributor cap on the TSP distributor is ~3/4” higher than the MSD cap so switching the wires from the MSD cap to the CRT cap was not an issue.  Both caps in this case incorporated HEI terminals so no problems were encountered in switching the spark plug wires from one cap to the other.  With the ignition timing for the CRT distributor set exactly the same as the MSD distributor (39° total), the engine was run on the dyno and it made exactly the same horsepower as the MSD distributor so the electronics are doing their job.
 
I found no issues with this new distributor so I heartily recommend it to anyone with an early ‘Bird wanting to retain the factory mechanical tachometer.  Be forewarned that there are blocks out there with distributor cavities that are on the shallow side and appropriate changes must be made to accommodate those particular blocks.  That would involve either relocating the gear higher on the shaft for those shallow holes or a thin shim where the distributor and the block mate up to space the distributor up accordingly.
 
This particular distributor gets a clean bill of health and will be prepared for use in Paul’s engine.

Lorena, Texas (South of Waco)

Good information, thanks.....................

64F100 57FAIRLANE500

Good morning, Ted.

I'm confused by your numbers. There's approximately a 1-inch difference in gear placement between the CRT and the 57 manual specs. Is this a typo?

Thanks

Good catch as that was a typo.  I’ve gone back into that post and fixed that.  Only the inch number changed and not the decimal portion.  Thanks for the alert to that.

Lorena, Texas (South of Waco)