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Rich
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Joined: August 07, 2003
Posts: 158
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 Posted: Fri Aug 15, 2003 10:06 am Post subject: Finding TDC |
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1972 1700cc motor, Westy.
I installed the heads w/o noting the position of the cylinders. I also disassembled the rocker arm assemblies, so slackness in the adjusters doesn't tell me much re: TDC
The fan is installed. The notch on fan is lined up with "0" on timing scale. If I remove the approximately 1 1/2" black timing hole cover/plug from the top of the fan housing, the "0" on the fan is lined up with the indicator notch. Looking through the spark plug hole I can see that the # cylinder is at the top of it's stroke. I set the timing shaft with the notch at 12 degrees relative to the casing. The smaller part of shaft top relative to the dog-ear groove is facing outward. The distributor went in nicely, and the rotor faces right at the #1 indicating notch on the edge of the distributor.
It appears that I am at TDC on the #1 cylider, but does that necessarily mean that the cylider is on it's firing stroke? I am concerned that it could be on the exhaust stroke.
Trying to be extra certain, don't want to try to figure this one out after I install the engine.
Thanks,
Rich |
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TimGud
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Joined: March 03, 2002
Posts: 6459
Location: Rio Rico Arizona
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| Posted: Fri Aug 15, 2003 12:40 pm Post subject: |
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| One way to be sure is to back the motor up a revolution,have someone push a pushrod into the intake pushrod tube to the intake lifter ,then rotate the motor clockwise by hand and watch as it pushes the pushrod out, then goes back in ,then after it goes back in align your timing mark and you have found #1 tdc. |
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NeverHadaBeetle
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Joined: October 08, 2002
Posts: 442
Location: Missouri
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| Posted: Fri Aug 15, 2003 4:36 pm Post subject: |
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Assuming your distributor is installed correctly then it sounds like you are indeed at TDC for #1. If you distributor is 180 out then you are at BDC which is TDC of the exhaust stroke. If I were you I would install the plug wires, set the valves, set the timing statically, and fire it up. Good luck.
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With a thousand screamin' trucks
An' eleven long-haired friends a' Jesus
In a chartreuse micra-bus." |
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Tcash
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Joined: July 20, 2011
Posts: 12846
Location: San Jose, California, USA
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| Posted: Fri Sep 04, 2015 2:43 pm Post subject: Finding True TDC |
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To link to this thread
| Code: |
| [url=http://www.thesamba.com/vw/forum/viewtopic.php?p=7810556#7810556]Finding True TDC[/url] |
Finding TDC Type I Engine.
| Bruce Amacker wrote: |
1. Take an old spark plug and grind the top chamfer from it.
2. Grind or cut the ground electrode off.
3. Use a punch and knock the porcelain out from the bottom.
4. Run a 3/8" NC tap through the empty spark plug shell.
5. Snug a 3/8" x 3" long bolt into the shell.
5.5 Remove #1 plug with your finger over the spark plug hole turn the crankshaft pulley clock wise until you feel pressure, stop.
6. With the piston halfway down snug your new tool into the hole.
7. GENTLY rotate the engine until the piston stops against the tool.
8. Make a pen/pencil mark on the pulley at the engine case split, be exact.
9. Rotate the engine in the opposite direction until the piston again touches the tool.
10. Make another mark with a pen.
11. Measure the distance between the two marks and divide in half. Find the exact halfway point between the two marks, this is your EXACT TDC.
REMOVE THE TOOL!
I had only about 10 minutes in this, and that included making the tool.
Have a great day!
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Finding TDC Type IV Engine
1. Take an old spark plug and grind the top chamfer from it.
2. Grind or cut the ground electrode off.
3. Use a punch and knock the porcelain out from the bottom.
4. Run a 3/8" NPT tap through the empty spark plug shell.
5. Thread a 3/8" barbed hose fitting with teflon into the shell.
6. Connect a length of clear plastic tubing to the fitting.
7. Remove all spark plugs.
8. Stick your thumb OVER the #1 cylinder spark plug hole. Rotate the engine until you feel pressure on your thumb. That's the compression stroke.
9. Screw in the spark plug with plastic tubing attached and insert the other end of the tube into a jar of light oil. Continue rotating the engine. Bubbles will appear until the piston reaches the top of its travel. When it starts down on the next stroke, the bubbles will stop and oil will begin traveling up the tube. Stop at a convenient point and mark the tube. Then mark the crank pulley and the engine body at a convenient spot.
10. Rotate the engine backwards and watch the oil recede into the jar. Continue rotating. As the piston continues past TDC and downward it will again suck oil into the tube. Rotate the engine till the oil again reaches the mark. STOP! Mark the crankshaft pulley where it lines up with the mark you made previously on the engine. You should now have two marks on the crankshaft pulley. The midpoint of these two marks lined up with the mark on the engine is TDC.
http://www.wikihow.com/Find-Your-Engines-Top-Dead-Center-TDC
https://ww2.gates.com/europe/file_display_common.c...5005%2Epdf
Last edited by Tcash on Thu Aug 24, 2017 5:12 pm; edited 3 times in total |
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Wildthings
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Joined: March 13, 2005
Posts: 52290
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| Posted: Fri Sep 04, 2015 8:59 pm Post subject: |
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Both of your intake and exhaust rocker arms should have play at TDC compression for #1. When you rotate the engine 90° in either direction from TDC the rockers should NOT move and you should still have play in both rockers.
If you are one full turn of the crank out from TDC compression for #1 the rockers should not have play at TDC and they should move as you rotate the engine back and forth within 90° either side of TDC. |
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1967250s
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Joined: May 02, 2007
Posts: 2137
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| Posted: Sat Sep 05, 2015 12:23 am Post subject: |
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Being a '72 1700, you should have a plug on top of the fan housing to check the timing. At TDC there should be a slot in the edge of the fan- looking down inside the hole- and a V notch to line up. It is much more accurate than the scale by the fan belt or sticking things in the spark plug hole. There were a couple recent posts on the whole fan and 914 engines and timing marks, research them.
Just found it!
http://www.thesamba.com/vw/forum/viewtopic.php?t=636711&sid=b2da0fda7b863944fa86ab885b0c743b
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SGKent 
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Joined: October 30, 2007
Posts: 42416
Location: at the beach
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| Posted: Sat Sep 05, 2015 9:32 am Post subject: |
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this is a 2003 post. A little old. Do not use the bolt method. Some poor guy forgets it, hits the starter, punches a hole in a piston and bends a rod. Besides that only works on a T1 motor because the spark plugs come from the side on a T4 motor.
Here is a helpful thread - http://www.thesamba.com/vw/forum/viewtopic.php?t=636711
Here is a helpful quote from Scott.
| germansupplyscott wrote: |
... maybe i can state it a different way:
you are looking for the overlap on #3. overlap on #3 is TDC on #1. overlap is when the rocker arms 'twaddle'. yes, that's a technical term  . take your index and middle finger and drum them on the table one after the other. that's the movement of the rocker arms on a cylinder at overlap. the intake rocker is just closing and the exhaust rocker is just opening and when they are both at the bottom of this motion this is the overlap point. when you find overlap on #3 then #1 is at TDC. on a flat engine like the VW it works for all cylinders that are opposite one another. overlap on #4 is TDC on #2, and so forth. |
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Tcash
Samba Member
Joined: July 20, 2011
Posts: 12846
Location: San Jose, California, USA
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| Posted: Sat Sep 05, 2015 11:33 am Post subject: Finding TDC |
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Here is a helpful quote from Scott.
| germansupplyscott wrote: |
... maybe i can state it a different way:
you are looking for the overlap on #3. overlap on #3 is TDC on #1. overlap is when the rocker arms 'twaddle'. yes, that's a technical term . take your index and middle finger and drum them on the table one after the other. that's the movement of the rocker arms on a cylinder at overlap. the intake rocker is just closing and the exhaust rocker is just opening and when they are both at the bottom of this motion this is the overlap point. when you find overlap on #3 then #1 is at TDC. on a flat engine like the VW it works for all cylinders that are opposite one another. overlap on #4 is TDC on #2, and so forth. |
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