Finding TDC - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Straight six · 08-19-2013, 01:48 PM

I'm trying to find TDC on 78 inline 250. There is no timing marks and I don't have a timing light. I took #1 spark plug out looked in the hole with flashlight and used a straw what am I looking for and feeling for. And the rotor on my hei is not pointing at #1 plug do I take the hei out then point to #1 plug then install carefully. This is not going well I look on the web and it sounds easy. Well now my truck won't start I turn the key it try's and backfires softly out of exhaust. Need help would love to drive my truck
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Straight six · 08-19-2013, 05:56 PM

Quote:

Originally Posted by Straight six

I'm trying to find TDC on 78 inline 250. There is no timing marks and I don't have a timing light. I took #1 spark plug out looked in the hole with flashlight and used a straw what am I looking for and feeling for. And the rotor on my hei is not pointing at #1 plug do I take the hei out then point to #1 plug then install carefully. This is not going well I look on the web and it sounds easy. Well now my truck won't start I turn the key it try's and backfires softly out of exhaust. Need help would love to drive my truck
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nheller76 · 08-19-2013, 06:52 PM

U need to watch the exhaust value go down then the intake go down. When the intake comes up u are on compression stroke. U then have someone turn the crank wile u stick a screw driver into the spark plug hole and feel the piston come up. When it starts to go down back it back up to the highest point. TDC!
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Straight six · 08-19-2013, 07:52 PM

What about the hei pointing at #1. What does that mean
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nheller76 · 08-19-2013, 10:37 PM

Quote:

Originally Posted by Straight six

What about the hei pointing at #1. What does that mean
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It means that it is making contact with the point on your distributor that is feeding the spark to your number one cylinder. Usually on a V8 u turn the rotor so it faces the #1 piston but u have a straight 6 so u can't really do that. Technically #1 can be anywhere u want on the distributor but u need to know the firing order so u can get the right sequence. Did u pull you distributor out?
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08-19-2013, 06:52 PM	#3
nheller76 Registered User Join Date: Sep 2012 Location: salem oregon Posts: 281	Re: Finding TDC U need to watch the exhaust value go down then the intake go down. When the intake comes up u are on compression stroke. U then have someone turn the crank wile u stick a screw driver into the spark plug hole and feel the piston come up. When it starts to go down back it back up to the highest point. TDC! Posted via Mobile Device __________________ Faith and Patience with my truck, that is what i pray for every day! See my build http://67-72chevytrucks.com/vboard/s...d.php?t=580013

08-19-2013, 07:52 PM	#4
Straight six Registered User Join Date: Aug 2012 Location: Newington ct Posts: 177	Re: Finding TDC What about the hei pointing at #1. What does that mean Posted via Mobile Device

08-19-2013, 01:48 PM	#1
Straight six Registered User Join Date: Aug 2012 Location: Newington ct Posts: 177	Finding TDC I'm trying to find TDC on 78 inline 250. There is no timing marks and I don't have a timing light. I took #1 spark plug out looked in the hole with flashlight and used a straw what am I looking for and feeling for. And the rotor on my hei is not pointing at #1 plug do I take the hei out then point to #1 plug then install carefully. This is not going well I look on the web and it sounds easy. Well now my truck won't start I turn the key it try's and backfires softly out of exhaust. Need help would love to drive my truck Posted via Mobile Device



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