I've been thinking about making a T.D.C. finder that would fit a pinto (with the head on)
has anyone done this already ?
[Edited on 4/3/09 by mcerd1]
Simple
Whip out a plug and put a very long screw driver done the plug hole and use it as a "feeler" to watch when piston 1 is at TDC. Careful
not to jam the screwdriver or damage anything.
OR
Whip of the rocker and watch the valves
yes, it is called a pencil or chopstick.
I should have said that I'll be using it for adjusting the valve timing so watching the valves isn't really an option....
quote:
Originally posted by mad4x4
Simple
Whip out a plug and put a very long screw driver done the plug hole and use it as a "feeler" to watch when piston 1 is at TDC. Careful not to jam the screwdriver or damage anything.
) 1:Something long down the spark plug hole,
2: rotate crank until pointer stops rising then put a mark on the crank pulley,
3: turn past tdc and then turn the engine backwards and again mark the crank when the pointer stops rising.
Halfway in between the marks should be TDC. The reason for doing it in both directions is to eliminate the few degrees at TDC where there is very
little piston movement compared to rotation of the crank, google: ineffective crank angle.
Cheers
Davie
isn't the crank key not machined at TDC? if so just project that up onto the pully
quote:
Originally posted by Mr Whippy
isn't the crank key not machined at TDC? if so just project that up onto the pully
quote:
Originally posted by mcerd1
quote:
Originally posted by Mr Whippy
isn't the crank key not machined at TDC? if so just project that up onto the pully
yes, but the mark on the block isn't directly above the pulley - its offset to about 10 o'clock(ish)
The "thing down the plug hole" trick as described by Daviep is the method advised by Dave Walker.
It's what I'm going to use on my upcoming EFi installation....
Used it on a Francis Barnett 50cc motorcylce when I was 16, problem was the pencil disappeared, big hole in piston.
cheers all
actually now that I look at it again - all I'd need is pushrod/extension for the DTI and something for it to slide in smoothly
a bit like the vulcan video above, but I don't think it needs to be that long 
I'll bodge something together when I get a chance
What you need is a positive stop just before TDC , remove the porcelain and electrode from an old plug and replace with a bolt (being carefull not to
damge the thread).
Then simply turn the engine by hand till it stops on the `stopper` , mark the front pully , turn the engine in the opposite direction till it stops
again , and mark the pully again .
Exact TDC is smack bang in between the two marks - super accurate , and costs precisely nothing to do .
The trouble with using a DTI down the plug-hole is that the plug will be angled , and this can snap the end off the DTI leaving you with something
(often non-magnetic...) sitting in the combustion chamber (dont ask me how I know that one......... )
quote:
Originally posted by clairetoo
What you need is a positive stop just before TDC , remove the porcelain and electrode from an old plug and replace with a bolt (being carefull not to damge the thread).
Then simply turn the engine by hand till it stops on the `stopper` , mark the front pully , turn the engine in the opposite direction till it stops again , and mark the pully again .
Exact TDC is smack bang in between the two marks - super accurate , and costs precisely nothing to do .
The trouble with using a DTI down the plug-hole is that the plug will be angled , and this can snap the end off the DTI leaving you with something (often non-magnetic...) sitting in the combustion chamber (dont ask me how I know that one.........
I've been doing it this way for about thirty years (yep , started very young 
) , the DTI method only works with a twin cam/central plug setup
- and even then it's not very accurate as there will be a significant dwell period at TDC (when a few degree's of crank movement makes no
significant change to piston position)
You don't look a day over 21.
quote:
Originally posted by clairetoo
What you need is a positive stop just before TDC , remove the porcelain and electrode from an old plug and replace with a bolt (being carefull not to damge the thread).
Then simply turn the engine by hand till it stops on the `stopper` , mark the front pully , turn the engine in the opposite direction till it stops again , and mark the pully again .
Exact TDC is smack bang in between the two marks - super accurate , and costs precisely nothing to do .
The trouble with using a DTI down the plug-hole is that the plug will be angled , and this can snap the end off the DTI leaving you with something (often non-magnetic...) sitting in the combustion chamber (dont ask me how I know that one.........
quote:
Originally posted by clairetoo
as there will be a significant dwell period at TDC (when a few degree's of crank movement makes no significant change to piston position)