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One Cylinder Low Compression-Post Valve Adjustment https://slantsix.org/forum/viewtopic.php?t=3487 |
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Author: | Mitch [ Tue Apr 16, 2002 7:27 pm ] |
Post subject: | One Cylinder Low Compression-Post Valve Adjustment |
I went through the valve adjustment not expecting things to be any better for my effort. Here's what I found: All the intake adjustments were virtuually dead-on. All were between .010 and .011. The exhausts, however, were tight. The lash on the problem #5 cylinder was .014. All others were about .018. I last adjusted the valves about 50K ago. I now have about 110K. I made my current adjustments after about one hour of running time with temps stabilized. I set the lash a bit on the loose side at .011 and .021. The result? The engine now runs smooth. No miss. The idle vacuum went up from 19 to just over 20. I did not redo the compression check, but cranking the engine with the ignition disabled does not indicate an 'easy' cylinder as it had before. Conclusion? I believe the exhaust valves receeded. More so on #5. How long will the engine hold up? I'll stretch it for as long as I can. I went back to adding Marvel Oil to my gas. I stopped doing this after my second converter plugged up. I'd rather replace a converter than a head though. I also backed off on the spark timing a bit. Who would have thought a valve adjustment would have been so critical? Your thoughts? Thanks Mitch m5black@aol.com |
Author: | Doctor Dodge (Doug Dutra) [ Tue Apr 16, 2002 7:45 pm ] |
Post subject: | Re: One Cylinder Low Compression-Post Valve Adjust |
Valve adjustment is important, always something to be checked. Use the gas additive and drive the car easy, it should last a while. DD Quote:
:
: I went through the valve adjustment not : expecting things to be any better for my : effort. Here's what I found: All the intake : adjustments were virtually dead-on. All : were between .010 and .011. The exhausts, : however, were tight. The lash on the problem : #5 cylinder was .014. All others were about : .018. I last adjusted the valves about 50K : ago. I now have about 110K. I made my : current adjustments after about one hour of : running time with temps stabilized. I set : the lash a bit on the loose side at .011 and : .021. : : The result? The engine now runs smooth. No : miss. The idle vacuum went up from 19 to : just over 20. I did not redo the compression : check, but cranking the engine with the : ignition disabled does not indicate an : 'easy' cylinder as it had before. : : Conclusion? I believe the exhaust valves : receeded. More so on #5. How long will the : engine hold up? I'll stretch it for as long : as I can. I went back to adding Marvel Oil : to my gas. I stopped doing this after my : second converter plugged up. I'd rather : replace a converter than a head though. I : also backed off on the spark timing a bit. : : Who would have thought a valve adjustment would : have been so critical? : : Your thoughts? : : Thanks : : Mitch |
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