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Valve Noise?  Rate Topic 
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 Posted: 04-22-2008 02:54 am
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Mark Nardi
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My Jensen Healey's engine recently began making what sounds like a valve tap.  The noise ranges in tone and volume from that of a metal pen being quietly tapped on a metal desk to a loud almost popping sound.  The noise will usually quiet down at higher revs, but not always.  The engine seems to run rougher when the noise is louder (but that could just be my imagination).  The head has been reworked at some point, as evidenced by the bent valves in a bag O'parts provided by the previous owner.

Any suggestions of what this sound might be?  How does one start the process of checking for valve problems?


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 Posted: 04-22-2008 12:55 pm
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Brett Gibson JH5 20497
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Do a cylinder pressure test for starters, remember to have the carbs wide open when you do it, that will tell you if your engine has serious problems.

Brett

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 Posted: 04-23-2008 03:03 am
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Mark Nardi
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Prior to reading today's reply, I pulled the valve covers off and checked the clearances.  They all seem tight.  The exhaust side (the lower side) has clearances that run between 0.006 - 0.008.  The intake side runs between < 0.004 - 0.006.  Could this be the cause of my noise? 

I'm thinking that my next step will be to pull the cam housings and try looking at shims.  Which leads me to worry if the valves are shimmed to begin with.  If not shimmed then is the only way to gain clearance to grind stems (which means pulling the head)?  Is there any way to tell if the valves have been damaged short of pulling the head?  Or should I put it back together and do a compression test?

So many questions....

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 Posted: 04-23-2008 11:48 am
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Brett Gibson JH5 20497
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Mark, a compression test will tell you if you need to pull the head.  Factory valve clearance cold is exhaust 10 to 12, inlet 5 to 7, so your exhaust is a bit tight. Also it's a matter of shimming for clearance NOT grinding.

I really think you should do a comp. test before you get to involved.

Brett 

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 Posted: 04-23-2008 04:36 pm
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edward_davis
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Mark,  The valves are always shimmed: you can't run the engine without shims because of the way the cam followers are designed.  If you put it together without shims, the cam follower would rest on the spring retainer, which is not intiended to carry the force.  With a shim in place, the force goes directly to the top of the valve stem.  You may be in a tight spot, though, if your shims turn out to be too small.  I agree with Brett, though: you should do the compression test first.  You don't need to put the valve covers on if you do a cold test, but it's best to do the test at operating temperature.

Edward

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 Posted: 04-29-2008 01:45 am
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Mark Nardi
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Here are the compression results (run cold):

Cyl.   PSI Read
#1   130 - 140
#2   75 - 80
#3   135 - 140
#4   130 - 135

I hooked up the tester and cranked the engine until a maximum reading was reached as reported above.  The range is because I ran the test 4 times on each cyl.

Should I start looking for a rebuild kit, someone to rebuild for me, or are there more diagnostics to be run?  Someone suggested that the cause may be a blown head gasket.

Thanks.

Last edited on 04-29-2008 03:08 am by Mark Nardi

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