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how dead nuts is "top dead center"

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Old 09-08-2011 | 07:52 AM
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DEOR's Avatar
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From: North Georgia
Year: 1988
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Default how dead nuts is "top dead center"

got spark and fuel, crank, no start...

Double checking my timing and when i put #1 cyl at , what looks to me, top dead center, my rotor button seems to be past 1, more between 1 AND 5 post.
When i rotate engine so rotor button is at 1 post, it seems that my piston is slightly lower then top.

How dead nuts does this need to be? Am i over thinking this?
Old 09-08-2011 | 08:12 AM
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If you're trying to index your distributor, it's very important. You really need a sacrificial dizzy cap to do this right. You cut a window into the cap so you can see the #1 terminal in the cap. The rotor's trailing edge should be .020" past the #1 terminal at TDC.
Old 09-08-2011 | 09:34 AM
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great thanks for the info,

can you go into indexing the distributor a bit more.

setting timing is new territory for me.
Old 09-08-2011 | 11:26 AM
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Originally Posted by DEOR
great thanks for the info,

can you go into indexing the distributor a bit more.

setting timing is new territory for me.
There should be alignment holes in the distributor. 2 that you can see when you take the coil off, and 1 underneath. Spin it so the 2nd hole on the top aligns with the hole underneath and drop a pin in it to hold it there. Turn the oil pump drive to 11 o'clock, put the motor TDC and it should drop right in and be perfectly lined up.
Old 09-08-2011 | 11:33 AM
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how dead nuts is "top dead center"-image-1046626631.jpg
Old 09-08-2011 | 05:59 PM
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Originally Posted by CattyXJ
There should be alignment holes in the distributor. 2 that you can see when you take the coil off, and 1 underneath. Spin it so the 2nd hole on the top aligns with the hole underneath and drop a pin in it to hold it there. Turn the oil pump drive to 11 o'clock, put the motor TDC and it should drop right in and be perfectly lined up.
Good info for 91 and later but irrelevant for a Renix.

To the OP: My post #2 is how you index the distributor on a Renix. It has nothing to do with your ignition timing.
Old 09-08-2011 | 06:11 PM
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Originally Posted by cruiser54
If you're trying to index your distributor, it's very important. You really need a sacrificial dizzy cap to do this right. You cut a window into the cap so you can see the #1 terminal in the cap. The rotor's trailing edge should be .020" past the #1 terminal at TDC.
Yes

OP - as cruiser just stated - when you are at TDC the rotor should be slightly PAST the #1 post. If it fired right when you reach TDC it would be too late - hence the purpose of timing advance.

The teeth on the distributor (at least on an HO) are pretty big and being a tooth off is pretty obvious.
Old 09-08-2011 | 06:14 PM
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Originally Posted by cruiser54

Good info for 91 and later but irrelevant for a Renix.

To the OP: My post #2 is how you index the distributor on a Renix. It has nothing to do with your ignition timing.
Didn't catch the year in any of that.
Old 09-08-2011 | 06:15 PM
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Originally Posted by CattyXJ
Didn't catch the year in any of that.
It is in his signature.
Old 09-08-2011 | 06:18 PM
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Originally Posted by Evil Drew M
It is in his signature.
Gotcha. Can't see that on the iPhone app.
Old 09-08-2011 | 07:37 PM
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Originally Posted by Evil Drew M
Yes

OP - as cruiser just stated - when you are at TDC the rotor should be slightly PAST the #1 post. If it fired right when you reach TDC it would be too late - hence the purpose of timing advance.

The teeth on the distributor (at least on an HO) are pretty big and being a tooth off is pretty obvious.
Same size teeth on a Renix.
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