Finding TDC bassackwards
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From: Eagle IDAHO
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Finding TDC bassackwards
Here I am putting on a StreetDamper, and new timing pointer. While thinking about the traditional method of verifing TDC on #1 and the awkwardness of trying to get the piston accurately to the top with a feeler through the plug hole. It dawned on me that since I've got the plugs out, why not screw my air hose/spark plug adapter into the cylinder which will be at BDC when #1 is at TDC and let the air pressure drive the BDC piston to the bottom.
But off the top of my head I can't remember which cylinder is at BDC when #1 is at TDC. Help me here please, I'm having a senior moment.
[Modified by NHVett, 7:27 AM 2/27/2002]
But off the top of my head I can't remember which cylinder is at BDC when #1 is at TDC. Help me here please, I'm having a senior moment.
[Modified by NHVett, 7:27 AM 2/27/2002]
Instructor
Joined: Sep 2000
Posts: 193
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From: Jefferson, GA, USA
Re: Finding TDC bassackwards (NHVett)
A good way to make sure that you are not 180 deg. off is to have your valve cover removed so that you can see if the valves are opening at the right time.
Put your timing mark at zero on the balancer. Slowly turn the motor (by hand) and make sure it is the exhaust valve that opens first and not the intake valve. Then turn the motor backwards, back to the zero. Now you know that you are at TDC on the compression stroke. Pop in the distributor with rotor facing no. 1. This has always resulted in 100% reliability for me.
Good luck.
Put your timing mark at zero on the balancer. Slowly turn the motor (by hand) and make sure it is the exhaust valve that opens first and not the intake valve. Then turn the motor backwards, back to the zero. Now you know that you are at TDC on the compression stroke. Pop in the distributor with rotor facing no. 1. This has always resulted in 100% reliability for me.
Good luck.
Drifting
Joined: Dec 2000
Posts: 1,733
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From: Sarasota FL
Re: Finding TDC bassackwards (NHVett)
Hers what I do:
1- remove #1 plug
2- put finger over the hole and rotate the engine. when air pressure blows out you are approching TDC on firing stroke.
3- install stop and rotate untill you hit the stop and mark it.
4- rotate backwards untill you hit the stop again and mark it.
5- the center between them is TDC.
your idea may work but you need to be more accurate.
1- remove #1 plug
2- put finger over the hole and rotate the engine. when air pressure blows out you are approching TDC on firing stroke.
3- install stop and rotate untill you hit the stop and mark it.
4- rotate backwards untill you hit the stop again and mark it.
5- the center between them is TDC.
your idea may work but you need to be more accurate.
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: Finding TDC bassackwards (NHVett)
Since the firing order is 18436572 and both 1 and 6 should be at TDC at the same time, wouldn't that make 4 and 7 at the bottom, and vice versa?
Now for something you didn't ask about ;) I lost my pisaton stop at one time and needed to locate TDC. I ran on down to the parts store and purchased the "spark plug non-fouler". They come 2 in a kit and cost under 2.50. I drilled and tapped out the center (which was MUCH easier than trying to bust all the ceramic out of the sparkplug) and used a piece of thick all-thread as my locator. The end of the allthread got rounded on the benmch grinder and then I ended up using jamb-nuts to mark the location of the piston both before and after TDC and then split the distances in half. Of course you HAVE to disconnmect the battery and only rotate the engine over by hand!!!
Don't forget, if you can't locate TDC on piston #1 because too much stuff is in the way, piston #6 will give you the same results. -Matt-
Now for something you didn't ask about ;) I lost my pisaton stop at one time and needed to locate TDC. I ran on down to the parts store and purchased the "spark plug non-fouler". They come 2 in a kit and cost under 2.50. I drilled and tapped out the center (which was MUCH easier than trying to bust all the ceramic out of the sparkplug) and used a piece of thick all-thread as my locator. The end of the allthread got rounded on the benmch grinder and then I ended up using jamb-nuts to mark the location of the piston both before and after TDC and then split the distances in half. Of course you HAVE to disconnmect the battery and only rotate the engine over by hand!!!
Don't forget, if you can't locate TDC on piston #1 because too much stuff is in the way, piston #6 will give you the same results. -Matt-
