Results 1 to 27 of 27

Thread: Best way to find TDC??

  1. #1
    President Member
    Join Date
    Jan 2011
    Posts
    1,500

    Best way to find TDC??

    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.

  2. #2
    Silver Hawk Member
    Join Date
    Jun 2006
    Location
    Spokane, WA, USA.
    Posts
    7,835
    Any particular reason not to trust TDC mark on the front balance damper?

    jack vines
    PackardV8

  3. #3
    President Member
    Join Date
    Nov 2006
    Location
    South Bend,, In, USA.
    Posts
    1,049
    That would give you #1 TDC.

  4. #4
    President Member SScopelli's Avatar
    Join Date
    Jun 2010
    Posts
    1,370
    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

  5. #5
    President Member 5brown1's Avatar
    Join Date
    Aug 2008
    Location
    Fort Pierre, SD, .
    Posts
    881
    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.

  6. #6
    President Member
    Join Date
    Jan 2011
    Posts
    1,500
    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?
    Quote Originally Posted by PackardV8 View Post
    Any particular reason not to trust TDC mark on the front balance damper?

    jack vines

  7. #7
    President Member
    Join Date
    Jan 2011
    Posts
    1,500
    Goombah, I never finished HS........just want the sixth grade explanation.....:-)
    Quote Originally Posted by SScopelli View Post
    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

  8. #8
    President Member
    Join Date
    Jan 2011
    Posts
    1,500
    No UDC marker on my Avanti damper, as to bumping the starter, I will use a remote start trigger to advance the engine...
    Quote Originally Posted by 5brown1 View Post
    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.

  9. #9
    President Member
    Join Date
    Oct 2004
    Location
    Southern Maryland
    Posts
    671
    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.
    Last edited by Mike; 01-08-2018 at 02:31 PM.

  10. #10
    President Member Ron Dame's Avatar
    Join Date
    Feb 2006
    Location
    Asheville, NC
    Posts
    1,493
    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?
    Ron Dame
    '63 Champ

  11. #11
    President Member Jerry Forrester's Avatar
    Join Date
    Aug 2007
    Location
    Douglasville, Georgia, USA.
    Posts
    3,032
    Quote Originally Posted by Hawklover View Post
    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.
    Jerry Forrester
    Forrester's Chrome
    Douglasville, Georgia

  12. #12
    President Member
    Join Date
    Jan 2011
    Posts
    1,500
    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
    :-(
    Quote Originally Posted by Jerry Forrester View Post
    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.

  13. #13
    President Member 5brown1's Avatar
    Join Date
    Aug 2008
    Location
    Fort Pierre, SD, .
    Posts
    881
    The dampers on my studes all have UDC rather than TDC. Both reference the same position.

  14. #14
    President Member
    Join Date
    Nov 2006
    Location
    South Bend,, In, USA.
    Posts
    1,049
    Quote Originally Posted by Ron Dame View Post
    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.

  15. #15
    Golden Hawk Member StudeRich's Avatar
    Join Date
    Dec 2005
    Location
    Ferndale, WA, USA.
    Posts
    27,379
    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.
    StudeRich
    Second Generation Stude Driver,
    Proud '54 Starliner Owner




  16. #16
    President Member
    Join Date
    Apr 2005
    Location
    Great Falls VA
    Posts
    3,220
    Quote Originally Posted by DieselJim View Post
    Use a socket on the nut on the alternator......
    Never tried this but I will now. Usually on anything other than an R-series, just grab the belt and pull, even with the plugs in...
    64 GT Hawk (K7)
    1970 Avanti (R3)

  17. #17
    President Member Noxnabaker's Avatar
    Join Date
    Sep 2015
    Location
    Sweden
    Posts
    631
    Hawklover, you can put the vac at any position & then you just change the wires position, as long as the rotor points at #1 when it should.


    Josephine
    -55
    Champion V8
    4d sedan

  18. #18
    President Member
    Join Date
    Jan 2011
    Posts
    1,500
    Many thanks, I thought I had to have the vac and rotor facing number one spark plug.
    Quote Originally Posted by Noxnabaker View Post
    Hawklover, you can put the vac at any position & then you just change the wires position, as long as the rotor points at #1 when it should.

  19. #19
    President Member
    Join Date
    Jan 2013
    Location
    british columbia
    Posts
    1,028
    The vacuum and rotor can be anywhere if it has been rewired or is going to be rewired. If you want to replace it in the same position as it came out, yes #1 TDC and follow #1 wire back to the distributor and mark it with a paint pen, when the distributor is installed it will turn when it is inserted, therefore you will have to start it approximately in the position of #2 wire and when it rotates it should end up at #1 when fully inserted. This may take two or three tries. The gears have to mesh so that #1 TDC is lined up and also the oil pump slot is lined up. It is not as easy as just dropping it in. On a 6 you could only be out 180, however on a V8 you could be out multiple degrees in either direction. I spent about 30 minutes installing my distributor in my 259 before I got it right.

  20. #20
    Silver Hawk Member
    Join Date
    Sep 2005
    Location
    Washington, DC, USA.
    Posts
    5,651
    Quote Originally Posted by Jerry Forrester View Post
    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.
    Rocket surgery??????

  21. #21
    Golden Hawk Member StudeRich's Avatar
    Join Date
    Dec 2005
    Location
    Ferndale, WA, USA.
    Posts
    27,379
    What most people forget is, that once you have the Rotor lined up with the actual #1 firing position and you are sure the #1 is at the top of the compression stroke, there is NO reason to waste time sweating that Oil Pump slot position thing.

    Just lightly press down on the Dist. while you crank it with your other hand on the Remote Starter Button, and it will drop into the Oil Pump and then drop all the way onto the Block surface, ...Done!

    Snug up the Dist. Clamp Bolt, and you are ready to fine tune the Timing with your Timing Light and then lock the Clamp Bolt.
    StudeRich
    Second Generation Stude Driver,
    Proud '54 Starliner Owner




  22. #22
    President Member Jerry Forrester's Avatar
    Join Date
    Aug 2007
    Location
    Douglasville, Georgia, USA.
    Posts
    3,032
    Quote Originally Posted by Skip Lackie View Post
    Rocket surgery??????
    I meant to say 'brain science'.
    Jerry Forrester
    Forrester's Chrome
    Douglasville, Georgia

  23. #23
    President Member
    Join Date
    Jan 2013
    Location
    british columbia
    Posts
    1,028
    Quote Originally Posted by StudeRich View Post
    What most people forget is, that once you have the Rotor lined up with the actual #1 firing position and you are sure the #1 is at the top of the compression stroke, there is NO reason to waste time sweating that Oil Pump slot position thing.

    Just lightly press down on the Dist. while you crank it with your other hand on the Remote Starter Button, and it will drop into the Oil Pump and then drop all the way onto the Block surface, ...Done!

    Snug up the Dist. Clamp Bolt, and you are ready to fine tune the Timing with your Timing Light and then lock the Clamp Bolt.
    There is still some fineness required, as you turn the crank the cam also turns which also moves the rotor, while the oil pump stays still. It is not as easy as just dropping it in. I have been lucky some times and did it in 2 minutes and other times it was 1/2 and hour of fiddling.

  24. #24
    Golden Hawk Member StudeRich's Avatar
    Join Date
    Dec 2005
    Location
    Ferndale, WA, USA.
    Posts
    27,379
    By the time you get the Dist. down to where it is resting on the Oil Pump, it's already timed into the Cam Gear and will not change when it turns and drops into the Oil pump, as long as you do not let it raise up and become disconnected from the Camshaft it WILL be perfectly Timed to Number One.

  25. #25
    President Member Ron Dame's Avatar
    Join Date
    Feb 2006
    Location
    Asheville, NC
    Posts
    1,493
    Quote Originally Posted by Jerry Forrester View Post
    I meant to say 'brain science'.
    I thought it was rocket brains
    Ron Dame
    '63 Champ

  26. #26
    President Member
    Join Date
    Jan 2013
    Location
    british columbia
    Posts
    1,028
    Quote Originally Posted by StudeRich View Post
    By the time you get the Dist. down to where it is resting on the Oil Pump, it's already timed into the Cam Gear and will not change when it turns and drops into the Oil pump, as long as you do not let it raise up and become disconnected from the Camshaft it WILL be perfectly Timed to Number One.
    Yes Rich I do agree that will work perfect but you still have to back the rotor up just before #1 and as it is inserted it will advance to #1 where it remains timed now continue to rotate the engine until the distributor drops in the slot. Then check it with one complete rotation. Do I have it right now?

  27. #27
    Golden Hawk Member StudeRich's Avatar
    Join Date
    Dec 2005
    Location
    Ferndale, WA, USA.
    Posts
    27,379
    Yes, David (altair) that will work fine, thanks for adding more detail.

    When the engine is set at #1, I usually just drop the Dist. in so that the Rotor points straight forward when all the way down, of course doing what you say to be off about one Plug position at start.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •