Electrical: Best way to find TDC??

[Hawklover]

After removing #1 spark plug, does one keep ones finger over the plug hole and bump the starter till one feels his finger pushed off the hole?.......does one have to do this until the timing damper shows zero degrees at the same time one feels his finger 'blow' off the hole?

R series engines.

[PackardV8]

Any particular reason not to trust TDC mark on the front balance damper?

jack vines

[DieselJim]

That would give you #1 TDC.

[SScopelli]

There is a 2 to 3 degree advancement from when the piston reaches the top of the cylinder to its true TDC.

Using an indexing wheel on the crank you check where it comes up to the top and when it starts back down, then divide that delta by 2 and should be real close to exact TDC.

This delta between your measurement of TDC and what is on the dampener (PDC) maybe what is causing your doubt.

This is way over tech but if you want piston theory, here is a link..

http://www.epi-eng.com/piston_engine_technology/piston_motion_basics.htm

[5brown1]

Yes.
If you are alone put a rubber plug in the #1 hole and when it pops out you know it is on the compression stroke. Then use the UDC mark on the damper to get it exact.
I believe it would be harder to hold your finger over the hole while turning the engine over.

[Hawklover]

Not at all, just want to understand the steps I have to take when I remove and then put back the dizzy.
The zero mark on the damper has to come up in unison with my finger being pushed off the spark plug hole?

Any particular reason not to trust TDC mark on the front balance damper?

jack vines

[Hawklover]

Goombah, I never finished HS........just want the sixth grade explanation.....:-)

There is a 2 to 3 degree advancement from when the piston reaches the top of the cylinder to its true TDC.

Using an indexing wheel on the crank you check where it comes up to the top and when it starts back down, then divide that delta by 2 and should be real close to exact TDC.

This delta between your measurement of TDC and what is on the dampener (PDC) maybe what is causing your doubt.

This is way over tech but if you want piston theory, here is a link..

http://www.epi-eng.com/piston_engine...ion_basics.htm

[Hawklover]

No UDC marker on my Avanti damper, as to bumping the starter, I will use a remote start trigger to advance the engine...

Yes.
If you are alone put a rubber plug in the #1 hole and when it pops out you know it is on the compression stroke. Then use the UDC mark on the damper to get it exact.
I believe it would be harder to hold your finger over the hole while turning the engine over.

[Mike]

The problem is that the TDC and Timing marks align at both #1 & #6 TDC, 180 cam degrees out. That's why you need to be sure that #1 is on the compression stroke, by popping a cork, feeling the pressure, or checking that #1's rockers are loose.
I find TDC #1. Then I turn the engine over backwards, and ease up to align the timing marks. This takes any slack out of the gear train. Then I install the distributor so the rotor points to #1. I static set the timing by finding the point where the coil fires, and turn the distributor in the direction of rotation to take out slack, and carefully turn it against the direction of rotation until the coil fires.
I've found this is very accurate.
Mike M.

[Ron Dame]

An aside: since the crank bolt has the locking washer with tabs bent over the flats, how do you all turn an engine? I'm thinking deep pullies where an open end won't fit?

[Jerry Forrester]

Not at all, just want to understand the steps I have to take when I remove and then put back the dizzy.

This ain't rocket surgery. Just note where the vacuum advance and the rotor is and put it back in the same position upon installation.

[Hawklover]

Jerry, the last mechanic who worked on the car, just put back the dizzy in a haphazard way.....yes she fires correctly, but the vac advance is totally in the incorrect direction
:-(

This ain't rocket surgery. Just note where the vacuum advance and the rotor is and put it back in the same position upon installation.

[5brown1]

The dampers on my studes all have UDC rather than TDC. Both reference the same position.

[DieselJim]

An aside: since the crank bolt has the locking washer with tabs bent over the flats, how do you all turn an engine? I'm thinking deep pullies where an open end won't fit?

Use a socket on the nut on the alternator. That is how we would turn caterpillar engines. Might need to put pressure on the belt.

[StudeRich]

The way I do it, if it will not turn by pressing down on the Fan belt and turning the Fan, is just straighten the Lock Tab on the Crank pulley and use a 3/4 Drive 1 1/2 Inch Socket, 3/4 to 1/2" adapter and 1/2" Breaker Bar. You should not have to move it far if you use your remote starter button to get Close to UDC.