Subject: [TR] [TR6] dist drive gear not engaging?

From: "Brendan O'Shea" <[email-masked]>
Date: Sat, 25 Aug 2012 14:58:01 -0700

Hello all,

     After a multi-year restoration & engine rebuild on my 73 TR6, I'm to the
point of starting the engine. The bad news is : no oil pressure when spinning
the engine with the starter motor.

     My first guess was the new oil pump was bad, so I put another new one in
- didn't help. Pulling the distributor & spinning the oil pump with a 0.5"
dowel brings up the pressure, so the pump itself is working.

     I finally started measuring things - the shaft on the distributor drive
gear is 1.375" from the bottom of the shoulder of the gear and has a 0.3125"
slot cut in the end; the oil pump shaft is 3.25" from the pump housing to the
start of the tongue, the tongue is 0.3125" (matching the slot on the
distributor drive gear). I've uploaded annotated photos in case my description
doesn't make sense : http://www.flickr.com/photos/85259444@N03/

     Heres the problem: the distance from the top of the oil pump bush (what
the distributor drive gear sits on) to the top of the installed oil pump
shaft's tongue is 1.375", so the distributor drive gear is not engaging the
oil pump. The oil pump is mounted flush with the engine block, there is no
slop in the oil pump shaft when the oil pump is assembled. The lengths of all
3 oil pump shafts (original, 1st & 2nd replacement) match; the housings are
all identical in height, so I think those lengths are correct. The distributor
drive gear has a pin through the shaft, so I don't think that has slipped.

   Does anyone have a distributor drive gear they could measure the shaft on?
Is 1.375" the correct length? How about an oil pump - is 3.25" from housing to
start of tongue correct? This page :
http://www.mossmotors.com/forum/forums/10761/ShowThread.aspx says it should be
110mm (4.33"), but that can't be correct - maybe that is from top-of-rotor.

   What about the oil pump bush? Should that be flush with the engine block
from above or below? Mine is flush from below (oil pump side), about 0.125"
high on the distributor drive gear side. Note : I didn't remove this during
the rebuild, but I can't swear that the machine shop didn't; I don't feel any
gap below the lip of the bush, and it seems if it were any further in, the
gear wouldn't mesh with the cam.

  I've considered pushing the oil pump shaft out 0.125" - it is a press fit to
the rotor, so it might work - but it doesn't seem like I should have to do
that.

  Any idea what could be wrong?

Thanks in advance,
-Brendan O'Shea

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