mcerd1
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| posted on 4/3/09 at 12:21 PM |
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T.D.C. finder ? (DIY)
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]
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mad4x4
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| posted on 4/3/09 at 12:24 PM |
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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
Scot's do it better in Kilts.
MK INDY's Don't Self Centre Regardless of MK Setting !
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02GF74
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| posted on 4/3/09 at 12:34 PM |
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yes, it is called a pencil or chopstick.
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mcerd1
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| posted on 4/3/09 at 12:38 PM |
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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.
more or less my thinking, but I was going to machine up something to go in the plug hole to support some kind of lever with a ball or some plastic on
the end so it doesn't damage anything
maybe start with an old sparkplug and remove the centre (shouldn't be to hard - I've done it accedent a few times  )
make some sort of pivot to hold a bit of steel rod and weld an old bearing on the end
I'm hopeing that I can make something that would be able to push on a dial gauge :?
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daviep
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| posted on 4/3/09 at 12:48 PM |
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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
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Mr Whippy
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| posted on 4/3/09 at 01:11 PM |
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isn't the crank key not machined at TDC? if so just project that up onto the pully
Fame is when your old car is plastered all over the internet
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mcerd1
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| posted on 4/3/09 at 01:36 PM |
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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)
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Mr Whippy
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| posted on 4/3/09 at 02:30 PM |
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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)
how too linky
Fame is when your old car is plastered all over the internet
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BenB
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| posted on 4/3/09 at 02:33 PM |
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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....
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Canada EH!
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| posted on 4/3/09 at 04:46 PM |
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Used it on a Francis Barnett 50cc motorcylce when I was 16, problem was the pencil disappeared, big hole in piston.
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mcerd1
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| posted on 4/3/09 at 05:07 PM |
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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
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clairetoo
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| posted on 4/3/09 at 07:05 PM |
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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......... )
Its cuz I is blond , innit
Claire xx
Will weld for food......
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rusty nuts
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| posted on 4/3/09 at 07:19 PM |
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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......... )
Works a treat, been using this method for years
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clairetoo
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| posted on 4/3/09 at 07:25 PM |
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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)
Its cuz I is blond , innit
Claire xx
Will weld for food......
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rusty nuts
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| posted on 4/3/09 at 07:29 PM |
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You don't look a day over 21.
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daviep
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| posted on 4/3/09 at 09:07 PM |
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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 like that a lot. Simple and accurate.
Everyday is a school day.
Cheers
Davie
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02GF74
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| posted on 5/3/09 at 08:58 AM |
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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)
yep, it is quite suprising the number of degrees where the piston is not moving.
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