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question about TDC

Old 08-12-2001, 11:36 AM
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stickben
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Default question about TDC

Im currently in the process of putting a new intake on my 76. The haynes manual says to put the engine at TDC on the first piston before I remove the distributer. I followed the instructions but when the line on the harmonic balancer lines up with the zero mark the, rotor on the dist is never pointing directly at the line that i made for the #1 spark plug contact. Ive tried rotating it all the way around thinking that it may be at TDC on the compression stroke, but its even farther off than before, so I put it back to the position where the rotor is closer to the mark when the line is matched up with the zero line. Is this correct? Is it even nessesary to put it at TDC to remove the dist? I thought as long as the dist goes back into the engine in exactly the same position, then the timing will be ok.


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ben
Old 08-12-2001, 11:46 AM
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bob
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Default Re: question about TDC (stickben)

I think the TDC is for reference. At #1 TDC your rotor will be off by an amount depending on your initial advance. As long as you put the dist back exactly where it was and don't turn the motor over, it doesn't matter where it is but the replace has to be exactly the same place.
bob
Old 08-12-2001, 11:51 AM
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stickben
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Default Re: question about TDC (bob)

Also, how often should the cap and rotor be replaced? It looks like both cap and rotor have a little corrosion on the contacts.
Old 08-12-2001, 11:54 AM
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mean8t
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Default Re: question about TDC (bob)

The way that I always do it is to mark the distributor on the base right below the tip of the rotor with some paint. I also mark the intake. You will have to transfer a mark to your new intake. Then put it back in were it was. It should be close enough to get the car running and then you may have to adjust the timing slightly to get it right.
Old 08-12-2001, 11:56 AM
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mean8t
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Default Re: question about TDC (stickben)

I would replace them if you can. When you replce them buy one from Accel or another company that makes one with brass terminals on the cap and on the rotor.
Old 08-13-2001, 03:39 AM
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a smith
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Default Re: question about TDC (mean8t)

The outside ring on your harmonic balancer may have moved in relation to the the inner ring.It happened to me.I found this out when I rotated the engine and got close to TDC on the comp stroke with the #1 plug out.The timing mark was nowhere close.The balancer had rotated about 1/4 turn.I put a fuildamper on that cannot rotate.Now before pulling the distrib,put one mark(I use a black magic marker) on the distrib body and a corresponding marked on a piece of masking tape on the firewall,(use an arrow pointing up on both).Put another mark on the distrib body that lines up with the point of the rotor,(use a plus sign) and as you pull the dist out and the rotor turns and stops put your last mark on the the dist body that points again to the top of the rotor,(use a circle mark).Now when you go to reinstall the distrib you will have all the marks that you need to align everything up.As you start to insert the distrib shaft align the rotor with the circle on the distrib housing,as you bottom out the distrib align the arrow mark on the housing with the arrow mark on the firewall.Now look at the plus mark,this should be in line with the rotor.As long as you have not turned the engine over this should get your engine to start right up.And you will not have to bring your engine to TDC before pulling the distri if you use this method.It will be easier if the rotor is pointing toward the front of the engine before you start(it will be easier to see and make the marks).I wish I had the abilty to post pictures so that I could show you.It is really much easier to show you than to describe it.Good luck!!! :yesnod:
Old 08-13-2001, 07:32 PM
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theandies
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Default Re: question about TDC (a smith)

Dont' forget if your distributor dosen't seat all the way down on your intake the your oil pump driveshaft is out of alignment. Take a long flat blade screwdriver and a flashlight to turn the oil pump driveshaft to line up with the distributor. I always put a little assembly grease on the distributor gear and also the oil pump drive on the bottom of the distributor just to be on the safe side.
John
Old 08-13-2001, 08:29 PM
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killain
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Default Re: question about TDC (stickben)

It's not that close a deal, so long as you have it at TDC and you replace the distributor back in as close as you can to the position as you took it out and that it's in all the way and seats ok, then that's fine. Your going to have to set the timing again anyway. Just be careful and do everything slow and correctly, you'll be fine. :smash:

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