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06-30-2019, 06:57 PM | #1 |
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Finding. TDC How
What is the best way to find TDC on the flathead V8 . I need to do a leak down test. Thank you again BOB
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06-30-2019, 08:12 PM | #2 |
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Re: Finding. TDC How
Searc for the "zip tie method"
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06-30-2019, 08:22 PM | #3 |
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Re: Finding. TDC How
I agree, zip tie large end centered in the combustion chamber. Establish a pointer of some type on the crank pulley. Rotate the engine until it contacts the zip-tie end and mark the pulley. Rotate in the opposite direction to again contact the zip-tie end and again mark the pulley. TDC is half-way between the two marks. Repeat several times to assure consistency. If you search you should find detailed instructions.
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07-01-2019, 06:43 AM | #4 |
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Re: Finding. TDC How
Thank you JSeery I. Searched for the instructions but could not find them. I have a suspect cylinder 3 that I want to do a leak down test on . I have not obtained the tester yet .No point in obtaining one if I can’t figure out TDC . Thank you BOB
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07-01-2019, 07:04 AM | #5 |
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Re: Finding. TDC How
Take a zip tie insert the thick end through the sparkplug hole so it ends up over piston center.
Turn engine clockwise until piston hits zip tie and stops...slow and nice no forcing it!! Make a mark on pulley. Turn engine the other direction until it stops...mark pulley. Right between the 2 marks is TDC. |
07-01-2019, 08:34 AM | #6 |
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Re: Finding. TDC How
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https://www.fordbarn.com/forum/showp...16&postcount=4 The zip tie needs to be pushed in so that it is beyond the valves and over the piston. Any place over the piston works. The zip tie head provides a hard stop approaching TDC from one direction of engine rotation by hand and then once again by rotating the engine in the opposite direction. TDC is half way between the two "stops". Glenn Last edited by glennpm; 07-01-2019 at 10:31 AM. |
07-01-2019, 09:13 AM | #7 |
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Re: Finding. TDC How
As far as the leak down test goes, I would mark the crank pulley every 90 deg. One cylinder will be at TDC every 90 deg, so you just have to work your way through the firing order. Each cylinder it at TDC twice, only one of which is the compression stroke. It fairly easy to tell the compress stroke because of the air pushed out of the sparkplug hole.
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07-01-2019, 09:59 AM | #8 |
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Re: Finding. TDC How
Thanks. Everyone for your help I will give it a try . I’ve got a miss that I can’t put on the ignition . That is the reason for the leak down test Thanks. BOB
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07-01-2019, 01:32 PM | #9 |
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Re: Finding. TDC How
Leakdown may show a badly sealing valve but not a sticking one...putting a vacuum gauge on it will quickly give you a hint about what´s going on...just my 2c.
Last edited by flatheadmurre; 07-01-2019 at 02:47 PM. |
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