16 replies to this topic

[nicklouse]

without using the fly or pulley markings. I guess the best way is to fit a stop to one spark plug hole (home made) rotate engine one way to stop. then rotate the other way to stop marking the pully against the same mark each time and then divide the distance on the surface by 2.

 

is there a better way? (I am not taking the head off).

[jime17]

Dial gauge?

[nicklouse]

Dial gauge?

on what? more info?

 

 I don't have an extension that will reach that far into the engine. but that is another thing to think about.

[unburntfuelinthemorning]

without using the fly or pulley markings. I guess the best way is to fit a stop to one spark plug hole (home made) rotate engine one way to stop. then rotate the other way to stop marking the pully against the same mark each time and then divide the distance on the surface by 2.

I think that's probably the simplest way and will be very accurate.

[Bobbins]

 

Dial gauge?

on what? more info?

 

 I don't have an extension that will reach that far into the engine. but that is another thing to think about.

 

 

A dial gauge doesn't need to reach very far in, only enough to create dial movement at and around TDC.

[mini13]

yeah this really is the best way,

 

to be honest, i think the 20 mins faffing around making a dead stop will be quicker than any other method and its gonna be right. best thing IMO is to make it adjustable to you can get near to TDC then you have marks on the pulley/flywheel that are nice and close so its easier to interpolate for TDC, also you can use it with different dish sizes. Dont forget to put a nice radius on the end so it dosent dig in the piston.

 

 

 

without using the fly or pulley markings. I guess the best way is to fit a stop to one spark plug hole (home made) rotate engine one way to stop. then rotate the other way to stop marking the pully against the same mark each time and then divide the distance on the surface by 2.

 

is there a better way? (I am not taking the head off).

[nicklouse]

 

yeah this really is the best way,

 

to be honest, i think the 20 mins faffing around making a dead stop will be quicker than any other method and its gonna be right. best thing IMO is to make it adjustable to you can get near to TDC then you have marks on the pulley/flywheel that are nice and close so its easier to interpolate for TDC, also you can use it with different dish sizes. Dont forget to put a nice radius on the end so it dosent dig in the piston.

 

 

 

without using the fly or pulley markings. I guess the best way is to fit a stop to one spark plug hole (home made) rotate engine one way to stop. then rotate the other way to stop marking the pully against the same mark each time and then divide the distance on the surface by 2.

 

is there a better way? (I am not taking the head off).

 

yep was the plan have some hard plastic balls that can screw onto some threaded rod. and some old spark plugs.

[mini13]

i just had the bolt straigt onto the piston, IIRC the lat one i did was an old head stud and nut through plug, nut tacked to  the plug with mig and another nut to lock so it didnt move/ wiggle.

[DeadSquare]

You can rotate a crank a couple of degrees at TDC without a dial gauge registering any movement.

 

The most accurate place to measure piston movement is 1/2 way up (or down) the bore.

[nicklouse]

You can rotate a crank a couple of degrees at TDC without a dial gauge registering any movement.

 

The most accurate place to measure piston movement is 1/2 way up (or down) the bore.

that's why I am measuring either side of TDC and taking the middle as TDC.

[andyapanel]

I have whistle, similar to this:

 

 

I have never used it in anger, though.

[imack]

I made a dead stop to find tdc last time I timed my cam with the head on. Can you get a cam timing disc on the crank pulley bolt? Not sure that the dial gauge through a plug hole would be all that accurate unless you can reliably get onto a flat section of piston crown.

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[nicklouse]

been in the shed after work will weld up later. made it a size i can find and has a large allen head bolt so i can undo it it it gets stuck. might replace the end with some brass or alloy. as i have threaded the inside.

 

[croc7]

Piston position indicator.  Kinda like a hollow spark plug with a spring loaded, graduated 1/4" bar inside.  I think that they are used by the motorcycle mechanics.

[timmy850]

There's a video here with the basics - making one from an old spark plug and marking the pulley to find TDC

https://youtu.be/2Yh2ZpKHkq4