TDC how to locate

T

trevo

Senior Member
Ford Men what is the best way to locate TDC number 1 cylinder on my 34 without removing the head?
 
On any vehicle, remove the #1 plug and turn it over manually with your finger stuck in the hole. You will feel a sucking motion on the intake stroke and then air being pushed up against your finger on the compression stroke. At the top of the compression stroke, that cylinder's piston is at the top.....thus, TDC for #1.
 
dean333 said:
On any vehicle, remove the #1 plug and turn it over manually with your finger stuck in the hole. You will feel a sucking motion on the intake stroke and then air being pushed up against your finger on the compression stroke. At the top of the compression stroke, that cylinder's piston is at the top.....thus, TDC for #1.
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Why do you want to find TDC on a 34 engine. Are you planning to make a pointer and a TDC mark on the front pulley? It's pretty hard to get exact TDC. I think the best way is to make a pointer on the front cover to point to the edge of the front pulley, don't mark the pulley at this time, Now take one of those big fat plastic wire ties, stick the fat end down the plug hole so the it about over the piston, now buy hand, turn the crank, right hand rotation until the piston hits the plastic ball, now put a chalk mark on the pulley in front of the pointer, now turn the engine in the other direction until the piston comes up and hit's the plastic ball again, now make another chalk mark on the pulley in front of the pointer. now you'll find the 2 choke marks are about an inch or more apart, half way between to 2 marks is TDC. That's as close as your going to get it. Walt
 
To more precisely find TDC. Make a pointer stud to line up with the edge of the crank pulley. Do what Dean says. Then insert the big end (latch) of a wire tie into the spark plug hole to stop the piston. When the piston stops mark the pulley. Reverse rotate the engine until the piston stops again against the wire tie. Mark the pulley there. The distance half way between the marks is TDC. Make a permanent mark there.

Walt beat me to it.
 
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Thanks for the ideas never thought of a plastic cable tie I am going electronic ignition the 34s had no timing marks as did the later V8s just want to get it close as possible am fiddling with a bored out spark plug with a copper tube brazed into it connected to a water gauge the tie idea seems easier Cheers.
 
When you get the pulley marked as Walt and Phil described, have the wife hold the tip of the #1 spark plug wire, turn the ignition on and slowly hand crank the engine over. When she stiffens and lets out a yelp, check where the mark is and this will give you an idea where the timing is set. This tip only works 3 or 4 times before the wife gets wise to it and refuses to hold the wire anymore.
John
 
John that's pretty nasty....do you suggest Trevo do this before or after the electronic distributer is installed? LOL
 
That reminds me when I was a teen, I'd charge up a condenser and hand it to a girl in the car, they were bound to play with long enough until they touch the hot end. I did that once and slide in the car and gave her a kiss and spark jumped between our lips. That was the hottest kiss I've ever had. Walt
 
I call tyhis the Bruce Lancaster method of finding TDC. He posted it 10 or 15 years ago, been using it ever since. Biggest problem is: On some engines the combustion chamber is too big for the tie rap to hit anything.
 
At that point it is time to buy some hotrod parts!
On the early engines the tie wrap should work well...huge plug hole allowing a bigger lump to go in, and a completely flat area in chamber where everything should come together nicely.
The method is very quick, so mark your TDC with pencil, repeat the test several times, and if you wind up in the same place you know the blocker has been held in place properly and you have found a good and repeatable place. Once sure, mark your TDC at the marker with a chisel...for the marker on early engine, look at the bolts holding front cover on.
Replace one with a stud and nut, cut stud till you can get it in there and grind it to a point or chisel mark it.
I've posted a method using cardboard and protractor to make a template for the edge of your pulley so you can transfer degree marks established with a protractor directly to pulley edge, saving you the fun of figuring that your pulley circumference is 19.634854 and then dividing by 360 and trying to measure off the hideous number produced...
 
Some years ago I made a mark on the pulley on the old 21stud that is now in my 33 coupe. I used a bent piece of welding wire as a magic wand that rose and fell with the movement of the piston. I decided to test the cable tie method (18mm plug holes on my motor) and the result came out in exactly the same place. So if I were doing it again I would use the cable tie.

Mart.
 
GEEEEEEEEEEEEE!!! And all this AFTER I have removed BOTH heads on my flattie!! Oh well, it was good to see and prove that it is only .030 overbore and the walls still have the crosshatch marks from the overbore job as well as the full 4 inch stroke. Only about 1000 miles on the rebuild too.
Had to remove them to see why minimal compression on #1 slug.

Now to button it back up tomorrow with the nice new, shiney, pretty, copper head gaskets and see if it will still light up and run on its own....

With these new head gaskets I should be able to get about 500HP out of it now.... ha ha!
:D
 
thirt4, did you pinpoint what may have caused the lack of compression? (glad you're still working with the flatty).

Mart.
 
trevo said:
Thanks for the ideas never thought of a plastic cable tie I am going electronic ignition the 34s had no timing marks as did the later V8s just want to get it close as possible am fiddling with a bored out spark plug with a copper tube brazed into it connected to a water gauge the tie idea seems easier Cheers.
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If any one uses the bored out plug method use oil rather than water because it easy to suck the liquid into the cylinder.
 
Any visual system like a column of oil has more potential error than methods that block piston before and after TDC because engines with long rods and offsets (Flathead, SBC,etc.) have a dwell of 2-3 degrees at TDC during which even a dial indicator cannot distinguish an exact TDC point. This is probably academic and likely as close as your average production type timing tab, but the interference methods are a bit more accurate and are at least as easy.
With heads off, the piston can be stopped a ways down, somewhat increasing accuracy over stopping it high in the bore.
 
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