TDC

[Bingster]

Okay, put the finger in #1 and pushed the fan around. I don't know exactly how many revolutions it takes to get to TDC but it seems like more than one. Anyway, did feel the push on the finger and that was satisfying, in a mechanical way.  But the first time I got to TDC on the flywheel I passed it by about three inches. I kept going round and round, and finally I got to TDC again but was about an inch past the pointer.

 

I'm puzzled, though. When the finger first feels the push on it, it seems like there are three or four cylinder "pushes" past that. I don't know if I should check the pulley right after the first or if I have the entire number of pushes to hit DC. The pulley days DC and not TDC. I assume it's the same thing.

 

So obviously I'm very close to being right on DC but why the discrepancy?  Is it okay to be an inch off? Probably not. And my right arm is getting bruised by a nasty little sharp corner of radiator every time I move the fan. I know. Don't say it!

 

Anyway, I'm very pleased that I figured out how to get TDC, but I need to fine tune it a bit more.

[bacelaw]

What engine?  Does it have a plug on the top of the cylinder head towards the firewall?  If so, that's what the plug is for... finding TDC.

[Los_Control]

In a perfect world your method would be fine.

 

You need to remove the pipe plug on #6 cylinder .... then when you feel the air on #1, you need to insert a long wire and get #6 to tdc.

 

When 6 it is at TDC it will be on exhaust stroke while #1 is on intake and ready to fire. Because 1 was pushing the air out.

 

When you have a vehicle 75 years old, it is not uncommon for the lower pulley to be out of sync .... when you truly get it on TDC .... nobody here will be surprised  if the timing marks do not line up.

 

You really need to use the timing plug over #6 cylinder to get #1 on TDC firing position .... Then many have been known to remark the lower pulley to correct position.

Often they are just not correct anymore .... same time you will never know unless you use the pipe plug over #6

You can feel the compression coming from #1, you will know #1 is on it's firing stroke ..... you can only tell TDC from the # 6 pipe plug ... or a disassembled engine.

The spark plug is over the valves, not the piston .... you can not tell TDC from #1 cylinder. .... You need the pipe plug over #6.

 

 

[kencombs]

There are a number pulley and pointer combinations that will physically fit.   And only one combination will be correct.  Not uncommon to find mismatches.   So, the advice to find it with the plug over #6 and mark the pulley is good advice.

 

I had four engines on hand when I started on my pickup.   None of them were the same!  One piece pulley, two piece pulley, two different pointer configurations etc.

[Tom Skinner]

On e-bay they sell a TDC Whistle. I bought one. Cut the top off of a spark plug, glued the whistle on the end of a short hose (1" Long). at the top of the plug.

Screw it into no.1 cylinder turn you engine around by hand with the plugs out. The instance the whistle stops blowing your at TDC.

I also built a Micrometer with a longer Rod that inserts into no.6 cylinder passage at the top of the piston that works even more accurately. 

Either one works just depends which one you grab out of the cabinet first. Once at TDC your ready to remove the Distributor or re-time the engine or whatever.

[Dave72dt]

You'll get "3 or 4 pushes" of air because you're probably stopping to get a new grip on the fan/belt and there is still air in the cylinder as the piston continues on it's way up.  Compression stroke comes around every other complete rotation of the crankshaft.  Now that you're finding a compression stroke, you can use the rod on cyl 6.  If you go past TDC, you can go backwards  a bit and then forward again to your marks.

[DonaldSmith]

I once tried to check TDC by pulling the plug on Cylinder No. 6.  It was hard to tell when the stick really bottomed, especially with the problems I had turning the engine.  

 

Even with the spark plugs out, as should be, I could never turn the engine by pulling on the fan.  A few times I would pry the flywheel teeth.  Try that while watching the stick rise and fall.   Then I started just tunking the starter; the engine always seemed to stop past TDC.  Eventually it would hit a sweet spot. 

 

Lately, with the pusher fan working and the pulley fan removed, I have excellent shots with my battery-operated timiing light, from the right or left side of the engine, to see the timing marks clearly. 

 

As they used to day, "The proof of the pudding is in the eating."  With the timing about 4 to 6 dgrees before TDC, manifold vacuum is about 19 inches of engine vacuum.   Good enough for me.   My damper/pulley must still be together.     

[Bingster]

I did a post and it disappeared for some reason. Maybe I forgot to submit it. I have a Flathead 6. Yes, I have the pipe plug above #6.  Some good advice above. Thanks. Very ingenious the TDC whistle. Love to see a photo of it.

[Sam Buchanan]

[Bingster]

Have to ask why you modified the whistle?

[keithb7]

https://youtu.be/J5Wbyengb8U?si=Biko9ILXnYTqnwMp

[rcl700]

5 hours ago, Sam Buchanan said:

I take it you hear the compression stroke on #1?

[Sam Buchanan]

4 hours ago, rcl700 said:

I take it you hear the compression stroke on #1?

Correct.