Checking TDC

"Dave Plowman (News)" wrote in news: snipped-for-privacy@davenoise.co.uk:

Heh, now you can get a second or indeed a third opinion.

But is a dial gauge really *accurate* enough for you?

Surely that 1/100mm limit will stop you finding out *exactly* where TDC is?

What surprised me in this tread was the near total lack of basic mechanical knowledge of some...

Perhaps they measure bearing clearances with a ruler?

To be fair, most people wanting to know where TDC is are perfectly well served by a welding rod/pencil down the hole.

Using the right tool for the job is an important part of any task - but generally for this job an easily available, cheap and *accurate enough* tool is the *right* tool.

It's only because you wanted a much more precise measurement to satisfy your own curiosity that you need to go to more complicated and expensive setups.

As for bearing clearances for many car related tasks just feeling the play in whatever the bearing supports is 'accurate enough'.

That's not to say that sometimes sub-micron accuracy *is* needed, but it is to say that *sometimes it's not*.

This group generally gets a good balance between the 'official' way to do it and the pragmatic way that's good enough.

Yes - as a rough guide. But then the TDC mark on the crank already does this in my case - I simply want to check its accuracy. For my own curiousity, if nothing else.

Which is what I eventually found. About a fiver for the tool itself. A bit more for a 14mm adaptor if needed. Total cost including (expensive) P&P 15 quid.

But I made that clear from the outset. I'm perfectly aware of the many methods of finding an approximate TDC.

Again it might be. Or might not. Depends on what the application is and I thought I'd been clear about that.

I was pretty clear that I wanted something quite accurate. And poking pencils down plug holes is never going to be accurate - and more so if the plug ain't vertical.

Yes - but the answer I needed (and guessed was the likely one) - came up in the first couple of posts. It was all downhill after that. ;-)