Valve Seal Replacement
Valve Seal Replacement
Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
Heads on or off?
Re: springs, if the engine has never been overheated and free length measures consistent keep em. I guess you could measure the rate to see if you had some weak ones but if the engine was fine before, I wouldn't bother. I would not up the rate.
Rockers: inspect for wear and replace as req'd.
Might as well clean the pushrods.
Remember the Alamo and Goliad. GL
Re: springs, if the engine has never been overheated and free length measures consistent keep em. I guess you could measure the rate to see if you had some weak ones but if the engine was fine before, I wouldn't bother. I would not up the rate.
Rockers: inspect for wear and replace as req'd.
Might as well clean the pushrods.
Remember the Alamo and Goliad. GL
Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
That Eric sure is one smart feller. Could bb verify that by redoing the compression test after shooting some oil in the holes to see if it comes up? BTW Eric, is there a tech article on how to properly do a compression test?
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Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
I learned how a long time ago, back in the days of stone tools, before 'puter codes, but there are usually directions in any repair manual. 125-140 is a big spread, not as bad as the 0-90 spread I had on the last engine I worked on... Oil will be a good next step but I have seen good compression with bad oil rings also. So it is not a 100% definitive test but it helps narrow the field.
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Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
I have had carbon deposits on my intake valves on tear down and am under the understanding that one wants some oil to get to the guide. Would you guess I might be pulling to much oil down the intakes side or is running rich also a cause? (I know the carb fat on the bottom, but just havn't gotten a round to it. $$ and experience.) These are S/S valves on bronze guides. Am unfamiliar with the teflon pos seal, would it allow less oil to pass? This sure seems like a fine line to walk.
PS: bb don't mean to take over your post but you prob care about this stuff also.
PS: bb don't mean to take over your post but you prob care about this stuff also.
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New User
Joined: Dec 2003
Posts: 8
Likes: 0
From: Texas
This is all good to know. I'll run a wet comp test this weekend. When I did the dry, all the psi's remained steady. Took 2 or 3 cranks to get to max on all cylinders.
I'll be doing the job with the head on.
I'll be doing the job with the head on.
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
Make sure all the plugs are out and that the throttle is blocked open. All of the readings should be within 10% of the highest reading. Oil will make very little difference in a cylinder with good rings. I use regular engine oil in a squirt can.
The positive seal teflon units let less oil thru and are very good for intake valves. There are some people that feel that they do not allow enuf oil thru on the exhaust side and can cause accelerated wear rates. If you have a buddy rebuilding an engine at the same time share a set of teflon seals with him.
If you change valve seals with the head on use the rope trick to hold the valves up. It is easier than air. -IMHO
The positive seal teflon units let less oil thru and are very good for intake valves. There are some people that feel that they do not allow enuf oil thru on the exhaust side and can cause accelerated wear rates. If you have a buddy rebuilding an engine at the same time share a set of teflon seals with him.
If you change valve seals with the head on use the rope trick to hold the valves up. It is easier than air. -IMHO
