 Porsche Valve Adjustment, 1974 2.0 |
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| NJTom |
 May 4 2017, 05:24 PM
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#1
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Member  Group: Members Posts: 92 Joined: 16-July 14 From: NJ Member No.: 17,643 Region Association: None  |
While the 914 motor is out of the car to repair the rear main leak, I decided to recheck the valve adjustments because there seemed to be at least one making quite a bit of noise. When each cylinder wast brought up to TDC, I found the valve adjustments to be way too tight — all of them. Can’t quite figure that out as I checked, double checked, and triple checked the adjustments when the engine was on the stand. Who knows why that happened, but frankly, that’s not my concern. So I went through the motions of bringing each piston up to TDC and readjusted the valves. During the process, I just happened to pull on another rocker to see if there was any play — and there was — a lot. As a matter of fact, when #1 piston was @ TDC, there were other pistons at such a stage where at least one valve was closed. In measuring the lash of that closed valve, the gap was greater than when @ TDC in most cases. For example, when piston #1 was at TDC, the respective exhaust is @ .008 and the intake .006 — as they should be. However, when piston 1 is @ TDC, cylinder #2’s intake is closed — reading = .06 (as it should be) and Cylinder 4’s exhaust is closed with a reading of .12 — way too much. I checked and rechecked my findings.
Below is a little summary for all cylinders. When 1=TDC, #2 intake = .06 & #4 exhaust = .12 When 2=TDC, #1 exhaust = .11 & #3 intake = .13 When 3=TDC, #2 exhaust = .12 & #4 intake = .06 When 4=TDC, #1 intake = .13 & #3 exhaust = .11 All valves of all four cylinders are in spec when @ their respective TDC. I highly doubt this is normal. Logic says none of the gaps shouldn't be any greater than the TDC readings. |
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| Dave_Darling |
May 5 2017, 09:25 AM
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#2
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914 Idiot Group: Members Posts: 14,991 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California 
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My engine is the same way. I was never able to get a good answer about why it happens.
--DD |
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| NJTom |
May 5 2017, 09:31 AM
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#3
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Member Group: Members Posts: 92 Joined: 16-July 14 From: NJ Member No.: 17,643 Region Association: None |
QUOTE(Dave_Darling @ May 5 2017, 07:25 AM)  My engine is the same way. I was never able to get a good answer about why it happens. --DD So if I understand correctly (and I'm adjusting them now and would only like to do once). You agree with what Rich said and suggested? And THANKS! |
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Posts in this topic
NJTom Porsche Valve Adjustment May 4 2017, 05:24 PM
Marty Yeoman How are you establishing TDC? May 4 2017, 06:10 PM
NJTom
How are you establishing TDC?
TDC of cylinder ... May 5 2017, 05:05 AM stugray You are not at TDC when you think you are.
Do you ... May 4 2017, 08:07 PM r_towle I can make this easier for you.
When cylinder numb... May 4 2017, 10:05 PM jeffdon
I can make this easier for you.
When cylinder num... May 4 2017, 10:39 PM NJTom TDC of cylinder #1 is established using fan timing... May 5 2017, 05:04 AM sfrenck Read this thread.... then read it again.... then r... May 5 2017, 10:27 AM Dave_Darling What I know is that I use the 'book method... May 5 2017, 11:19 AM rjames
What I know is that I use the 'book method... May 5 2017, 12:26 PM |
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