MG Car Repair: Piper 285 Camshaft timing, crankshaft pulley, timing chain cover

Question
Hello Barrie,
I would like to thank you for your answers concern engine compression problems. The answers was very helpful.
I’m going to install Piper HR 285 camshaft in my MGB engine. Could you explain step by step how to setup the camshaft timing using  VERNIER TIMING GEARS. I have the engine outside the car and the head is off.
Best regards,
MAriusz


Answer
Hi Mariusz.  To do the job properly you need to beg, borrow or buy a dial gauge and an engine protractor.

With the head off and the timing chain cover on, set the gauge on top of the piston, attach the protractor to the crankshaft pulley, and confirm the true TDC position on the crankshaft pulley by turning the crankshaft clockwise and noting the minimum and maximum protractor readings where #1 piston is at the top of its stroke.  There is usually about 10 degrees of maximum lift at the top, and you are trying to find the middle of the maximum lift.  Keep turning the engine over clockwise, so that you take up any slack in the timing chain, and stop at the middle of maximum lift.  Look at the TDC markings.  You may be surprised how far true TDC differs from the markings on the pulley.  Mark the crankshaft pulley with the true TDC position.  I use a V-shaped file for this operation.

Having found the true TDC, rotate the protractor on the pulley, setting it to zero.  Now fit the head to the block.  I sometimes set up a piece of bent wire to mark TDC with the timing chain cover removed, so that I don’t have to keep removing and re-fitting the cover.

With your camshaft there should be a data sheet telling you when full lift occurs.  My old data sheet for the Piper 285 says 106 degrees after TDC, but your camshaft may be different.

Install the dial gauge so that it touches the top of the inlet valve for #1 cylinder.  (That will be the second valve from the front).  

Turn the engine clockwise, and this time note the minimum and maximum angles on the protractor where the valve is at maximum lift.  Calculate the middle point, which should be 106 degrees (or whatever your data sheet says).  If it isn’t set correctly, you will have to adjust the vernier wheel until you get the correct reading.