Need Help re. TDC

[dblinsqaun]

Still a relative newbie to my '74 tii.  Mistakenly pulled distributor without properly marking it nor at TDC to fix broken screw holding down points.  At any rate, now looking to set engine to TDC.  My buddy (quite mechanically inclined) and I can not for the life of us find the "port" up top in back nor in front to get engine to TDC.  This despite seeing pics in owner's and workshop manuals.  Certainly nothing we can point a timing light into or visually observe.  Nor do we see anything markers under front of car as I've read some people use marks at bottom of timing chain cover.  Pics would be greatly appreciated, from up close and further back for perspective.  I've attached a somewhat murky pic of the only thing we might think is the port, taken from the rear of the valve cover, passenger side.  Finally, what is the best way to turn the engine by hand.  Appreciate any help.

[zinz]

Nice write up in the Articles section

 

 

 

 

[TobyB]

Take out spark plug #1, or valve cover.

 

easy

 

t

 

[ray_]

Assuming a manual gearbox, I have taken to putting the car in 2nd and turning a (lifted) drive wheel. at least to set the valves.

 

Cheers,

[dblinsqaun]

Thanks all so far.  Back at it tomorrow I hope.  Toby, can you expand?  Pull the #1 plug then what?

 

[visionaut]

[visionaut]

It’s a simple/crude method — you can remove the #1 spark plug to find top dead center of Cyl 1.

 

Insert a small diameter wooden or plastic dowel into the spark plug hole until it contacts the top of the piston. As the engine is slowly rotated, the piston will force the dowel up and down. When the end of the dowel is at its highest point, the engine is at TDC for the #1 cylinder. (or 180 degrees off, since  4-stroke)
 

Caveat is the piston only rises/falls very slightly near the top dead center point, so it’s easy to be off a couple degrees.

Edited September 25, 2022 by visionaut

[Mark92131]

18 hours ago, dblinsqaun said:

Finally, what is the best way to turn the engine by hand.

 

Pull the plugs, put it in gear, roll it back and forth.  To find TDC, you can pull the valve cover, use @visionaut suggestion, and then verify that the cam lobe for #1 cylinder is off the valve stems and both valves are closed.  Also, the timing mark on the front of the cam should be lined up on the oil tube.  Then stab the distributor so the rotor lines up with the #1 spark plug lead on the distributor cap.

 

Mark92131

 

 

[visionaut]

Mark took you home, I only went to first base  lol

[dblinsqaun]

You guys are funny.  I read somewhere about putting the car in 4th gear, jacking up one side of the rear, turning the tire by hand.  That worked wonderfully for turning the engine.  Meanwhile, my buddy came by with a combo vacuum/pressure gauge.  We hooked it up to #1 cylinder and turned the tire till we got the inflection point between pressure (piston coming up) and vacuum (piston going down) - TDC.  Re-inserted distributor with rotor pointing at #1.  Car started right up and we tweaked the distributor rotation a bit to get it roaring.

 

I still don't understand how people are able to use a timing light thru that hole that Visionaut pointed out in my own picture.  Impossible to get to with all the crap in the way, beginning with the intake manifold.  I'll likely set timing by seat of the pants - just driving the car and going by how it feels.

[Hans]

Keeping in mind that #1 reaches TDC twice during a firing cycle. 

[dblinsqaun]

Yup, 50/50 chance to get it right first time.  But we did.

[tech71]

5 hours ago, dblinsqaun said:

 

I still don't understand how people are able to use a timing light thru that hole that Visionaut pointed out in my own picture.

It isn't easy, helps if the ball is marked with paint but I still have given up on it as a means of timing. Old bones, bad eyes.

I painted the indicator pin on the lower timing cover and marked my crank pulley like the one shown. Also not easy to get a clear view but less hard than "the ball" method.

My battery is in the trunk so that helps, get a clear view😉

Edited September 25, 2022 by tech71

[visionaut]

7 hours ago, dblinsqaun said:

I still don't understand how people are able to use a timing light thru that hole that Visionaut pointed out in my own picture.  Impossible to get to with all the crap in the way, beginning with the intake manifold.  I'll likely set timing by seat of the pants - just driving the car and going by how it feels.

Yay!

 

I showed you where the hole is, not that I use it.  Lol - lotsa ways to skin that cat…

[Tommy]

8 hours ago, dblinsqaun said:

Yup, 50/50 chance to get it right first time.  But we did.

But only once there is vacuum/pressure because the other time valves are open. First time I've heard about using a pressure gauge to find the TDC. Seems to work👍