Hello All,

Looking to replace my distributor and I am having a tough time finding TDC.

I am following the Haynes manual and this is the diagram shown:




I see engravings on my crankshaft dampener but my vehicle does not have the pointer to line up with the 0:



I can see a white paint line on the water pump pulley too:



Appreciate the help of the forum!

 

Never seen that before, or that bolt in the oil pan, does it go right into the pan, or does the hole stop.

There should be an inspection hole at the bottom of the trans bell-housing and a TDC timing mark on the ring gear.

If that's not there, then there is a way to find TDC and that bolt can be used with a piece of steel to create your own arrow.

 

I time my motorcycles accurately with a timing disc, sometimes called a degree plate, which is bolted onto the end of the crankshaft with a nearby pointer fixed to a handy bolt or screw.

It's first positioned as close to top-dead centre as can be found by looking or feeling down No 1 plughole on the firing stroke. A piston stop is made from an old hollowed-out sparking plug with a short, nicely-rounded rod welded to the inside and then screwed in with the piston halfway up its stroke, so that when the engine is slowly turned forwards, it's brought to a halt by the piston stop. A note is made of the degrees before tdc, turn it all the way backwards until it meets the piston stop in the other direction and tdc is exactly half way between those two points. The stop is removed, the disc is centralised so 0 degrees is aligned with the pointer and there you have it. Turn it back off tdc, put the piston stop back in and recheck forwards and backwards again to make sure the disc reads the same number of degrees each side of 0 degrees.Nought degrees is top dead centre and a permanent pointer with suitable degree marks can be made on the flywheel or front pulley for future timing.

These timing discs are available on ebay or from suppliers of classic motorcycle parts. I think my Dave Degens Timing Disc came free with a motorcycle magazine back in the '60s.

Ray

 

Is that an XJ6 sump? An alloy Mk2 sump has rows of parallel ribs on the oil pan while the XJ has just a few, sharply defined ribs in a square pattern. The XJ doesn't have the centre bottom timing pointer.

 

As Jeff stated I have not seen that sump design before. Mine on a 1968 S Type with an alloy sump has two tapped holes at the front for the arrow marker to be screwed into and I do not have that extra bolt. Could this be an after market sump that has been fitted?
Poor photo as it was not taken to show the timing mark but gives you an idea of what the front of my engine looks like with the timing arrow and two nuts holding it in place. The timing mark on the pulley cannot be seen.


To find TDC I remove the plugs and rotate the engine using a socket on the front pulley bolt. I insert a long thin screw driver in the back plug hole (number one cylinder) and slowly rotate the engine until the screw driver comes to the top and starts to drop again. This needs to be on the ignition stoke or just before it so you might have to take the cam cover off to note when the inlet valve closes just prior to the screw driver coming to the top of its highest point. If its the exhaust valve that is just closing then you are 180 degrees out. Having established TDC this way mark where the line on the front pulley with a line on the sump and then you can rotate the engine back slightly to give you the before TDC. If you had a timing wheel like Ray suggests you can then use this to set the degrees before TDC that you need. With me I tend to set the TDC just before, start the car and then rotate the distributor a fraction left or right until I find the sweet spot. All cars have a sweet spot that might not be due to age with wear and tear as per the manual which suggests 5 to 10 degrees. It also depends on which engine you have as an 8:1 compression engine will have a different timing set up from a 9:1 engine. The type of fuel you use also dictates what your timing should be, A higher RON rating allows you to advance the timing. My 3.4 with 9:1 pistons is running close to 10 degrees before TDC.

 

That bolt at the front corner makes it an XJ6 sump. They can be fitted to Mk2 engines with some work. However, it raises the question of whether the car has its original engine. Does it have a B type head like a Mk2 or the straight port of an XJ6? What's the engine number on the side of the block?

If the engine is from an XJ6, the pointer is (I think) on the water pump and visible from above if you look down past the alternator. It's a bit more convenient than the Mk2 arrangement.

 

I had the same problem, so i just ordered the pointer from Moss Motors - its bolts into place. IIRC i ordered the middle one.

 

Hello All,

Thank you everybody for your input. I am the new owner of the Mark II and the PO previously had the engine rebuilt. I appreciate your insights, it does make sense that the oil pan is from an xj6 as the car uses a spin-on oil filter.

Thank you for your advice, I will manually measure where TDC is.

Here is a photo of the engine:

 

Twins

 

Lovely car! Really are twins, my interior is also red!