Ignition timing

Its funny I have always taken the setting of the ignition timing to be a thing of simplicity; read the manual to see what the timing should be (lets say 8 degrees before the piston is at top dead centre). Attach a strobe light to spark plug number one, start the engine, turn the distributor until the pointer points to 8 BTDC. Done, have a cup of tea.

Vintage cars, no surprise had not evolved to the point where they had timing marks. Okay step one, read the manual – nope I don have one of those so revert to the internet. Zero degrees before top dead centre. Really? Okay i can live with that. 0 BTDC with the ignition fully retarded – oh thats the lever on the steering wheel, i remember. ok done. now what… of how do i know when the piston is at TDC? Back on the internet… use a ‘timing stick’. Oh one of those things that no one has seen in donkeys years – a tool that is screwed into spark plug socket number 1 and has a rod in the centre that is pushed upwards by the piston which then rotates the built in dial gauge so you can see down to one thousandth of an inch when the piston is at the absolute top of its arc.

Well I have a dial gauge that measures thousandths of an inch – and the race boys set the ignition at 5 degrees before TDC so a bit of simple maths taking into account the length of the piston conrod, the arc rotation of the crankshaft and some black magic means that i am looking for 8.5 thousands of an inch before TDC. Got it. but i still don’t have a timing rod – perhaps a bit of wood? Nope it wobbles in the plug hole, an 8mm brass rod? Better but still no. Oh bother lets make one properly…

FatBadger Garage timing stick instructions:

  • Take one spark plug
  • Remove all its internals
  • Fill the inside with a drill-able material (metal filler will do it)
  • Drill a hole a smidge wider than a rod of suitable length – beware of dropping the rod inside the engine!
  • insert new tool into spark plug hole no.1
  • rotate engine using the starting handle (i knew it would come in handy) until the engine is in the right place.
  • Rotate the engine until the points just open. Doh! I have rebuild the distributor so that it no longer has points…. umm
  • Rotate the engine until you get a spark at the end of the lead that would have gone to plug 1 – yep that’ll work
  • Robert is apparently now my  uncle

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Yes – i know… the dial gauge is showing 4 not 8.5 – i don’t seem to have a photo at its correct position and i am not going to do it all again. Whilst the valve covers are off, i will clean up the cylinder head a bit and replace the cork gaskets etc… onwards and upwards.

I have only one month before the car goes to the coach builder – i have some detailed design stuff to do…


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