How to: TDC indicator by the positive stop indicator.

[Mart]

Next time you are putting a motor together or just have a head off for a refresh, consider this little addition. It isn't difficult and can save a lot of head scratching later.

First you need to have a head off, and if no.1 cylinder is open, use that. If you only have the left head off, use number 6. As no.1's companion cylinder, it is at TDC at the same time.

Bolt a solid piece of metal across the centre of the cylinder. It has to be nice and strong. I used one of the brackets that came with my engine stand.




You then need to make up a simple pointer. You can get as inventive as you want, but I just bent something up from some scrap. I ground the end to a chisel point. Once the pointer is in place you carefully turn the crank in a clockwise direction and stop as the piston makes contact with the solid stop. Make a mark on the pulley in line with the pointer. This is a temporary mark, so I used some masking tape on the pulley so I could use a pen to make the mark.




Now you have to turn the crank almost one full turn anticlockwise until the piston comes into contact again with the stop. Make a second mark on the pulley.



Now you have to measure the distance between the marks and make a new mark half way between the first two. In my case this was easy as the marks were 40mm apart so I just made a mark at the 20mm point.

Then file a groove at that mark, as that is at TDC.

Remove the stop, take the tape off, stand back and congratulate yourself on how clever you are.



The whole job probably took probably less than a half hour.

A couple of notes: This works on a flathead because of the domed piston. For flat pistons, or any other type of engine you need a spacer of some sort on your solid stop to keep the piston below TDC.
Secondly, be careful when turning the motor over, because if your stop also goes across the valves, you could bend something. I didn't do this, but was wary of it.

Mart.

[40cpe]

Good job, Mart. I see some marks above the TDC point. Did you measure/mark some advance points?

[Mart]

Originally Posted by 40cpe

Good job, Mart. I see some marks above the TDC point. Did you measure/mark some advance points?

no, there is some damage on the pulley that looks like another mark. Murphy's law, I guess.

Mart.

[Walt Dupont--Me.]

I do that on about all my flatheads but instead putt that piece of metel across the top of the piston I just bolt a heavy piece on the block and have it stick over the piston about 1/2in. from the edge, that will put your 2 marks closer together, about 1in. apart and then 1/2 way between them. Walt

[Bill OH]

I used the same procedure, but with two differences: 1. I made the pointer from two pieces of strap iron welded together at one of the two bolt holes 3/8 NC, one strap going across both bolt holes and the other strap bent 90 degs with a pointer on it and drilled for the 38ths bolt, the two straps then welded together to maintain the correct position of the pointer. 2. I used a 1/2 inch drive socket secured on one of the head studs and used that as the stop.

The pointer can always be reinstalled in the correct position. My pointer is not bolted to the timing cover.

[Mike B]

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Timing tape is pretty cheap and might be more accurate than measuring over a circumference...plus added ability to continue your notches/scribes, in degrees and be able to use a timing light and be dead on with engine running...just tossing it out there fore more things for you to do

[Harylufa]

Hi
I did the same...I attach a pic

Hary

[40 Deluxe]

With timing tape, it has to be for the exact same diameter pulley as the one on your flathead. Do modern engines (for which there is tape) have the same diameter pulley as a flathead? Even more important, how will you get it to stick to that thin rim on the pulley? Modern engines have a wide flat surface on the harmonic balancer to put the tape on.

[51 MERC-CT]

Originally Posted by 40 Deluxe

With timing tape, it has to be for the exact same diameter pulley as the one on your flathead. Do modern engines (for which there is tape) have the same diameter pulley as a flathead? Even more important, how will you get it to stick to that thin rim on the pulley? Modern engines have a wide flat surface on the harmonic balancer to put the tape on.

Once you establish the location of T.D.C. there is no need for any other marking or tape.
Just about all the new digital timing lights will tell you what the timing is.

[Ol' Ron]

Two things wrong with this: If you remove the timing cover the pointer comes with it. Can't think of the other reason just yet. GHowever if the head is on use the Bruce lancaster method of sliging a larg tie wram through the spark plug hole. Then follow these directions. By deviding the circumfrence of the crank pullet by 360 you can get a 20 degree mark on the pulley as well as the TDC and that's the important one.

[Richard in Florida]

Originally Posted by 40 Deluxe

Even more important, how will you get it to stick to that thin rim on the pulley?

Maybe like this? Ignore the arrow.

[34PKUP]

Quote:
Originally Posted by 40 Deluxe
Even more important, how will you get it to stick to that thin rim on the pulley?

Originally Posted by Richard in Florida

Maybe like this? Ignore the arrow.

Unfortunately as pretty as yours is, it is not the same as the early single groove pulley that is referred to.

[Mart]

Thanks for all the lively discussion, guys, I just wanted to demo that it is quite a simple job. I did the same job on a 21 stud motor a decade ago and the front cover hasn't been off in that time so the makeshift pointer is fine for my needs. You can make it as fancy as you want to. Timing tape? Can't buy that at any parts places in the UK, plus the pulley isn't suitable. I have a snap on digital timing light so I only need the one mark.

Mart.

[51 MERC-CT]

Originally Posted by Mart

I have a snap on digital timing light so I only need the one mark.

Mart.

Right on with digital timing light, Ain't they amazing?

[Mart]

Originally Posted by 51 MERC-CT

Right on with digital timing light, Ain't they amazing?

Yeah, an excellent piece of kit. I like that it has a rev counter function. I can use it to check the curve of the dist. as the revs come up.

Mart.