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Old 06-11-2019, 07:08 PM   #21
30 Closed Cab PU
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Default Re: I think my exhaust valves are burnt

Would a worn distributor also cause this at idle? Timing not stable. Am asking , do not know.
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Old 06-11-2019, 07:21 PM   #22
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Default Re: I think my exhaust valves are burnt

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Would a worn distributor also cause this at idle? Timing not stable. Am asking , do not know.
Yes, worn distributor components can cause inconsistent idle.


Chris W.
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Old 06-11-2019, 07:31 PM   #23
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Default Re: I think my exhaust valves are burnt

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Yes, worn distributor components can cause inconsistent idle.


Chris W.


Then perhaps swapping in a know good distributor is worth a try before pulling the head.


Also perhaps inspect the valves through the spark plug holes with a fibre optic camera.
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Old 06-11-2019, 08:44 PM   #24
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Default Re: I think my exhaust valves are burnt

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Then perhaps swapping in a know good distributor is worth a try before pulling the head.
He says this in his initial post...

cyl #1-55psi cyl #2-63psi cyl #3-35psi cyl #4-65psi.

I don't think a different distributor will fix the compression on #3
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Old 06-13-2019, 07:21 AM   #25
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Default Re: I think my exhaust valves are burnt

I did a leak down test last night. I put 35 psi into cylinder 3 and it produced a loud hissing sound out the tail pipe, so it confirms my suspicions about the exhaust valve. I ordered a full gasket set (Including head gasket) and plan to pull the valve cover off tonight to check the clearances and to find out if I have adjustable tappets.
I ordered the gasket set from Macs and I picked the one with the silicone head gasket instead of the copper. They said it can be put on without any gasket sealer. Anyone have any experience with this type of head gasket??
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Old 06-13-2019, 08:04 AM   #26
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Default Re: I think my exhaust valves are burnt

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Have you pulled the side/valve chamber cover as suggested? You may just have a sticky valve or a bit of carbon under the valve. A lot less work than replacing a head gasket that may have been on for a long time - difficult to get off. Research or ask about ways to fix a sticky or carboned valve. Some add/spray Marvel Mystery oil in through the carb Intake, or add to the gas and drive for a while, for the sticky valve issue.
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Old 06-13-2019, 08:07 AM   #27
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Default Re: I think my exhaust valves are burnt

Sorry - need to read previous posts better - but there are things in previous posts to try.
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Old 06-13-2019, 08:40 AM   #28
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Default Re: I think my exhaust valves are burnt

Cancel the gasket order and buy the copper head gasket, so you won't have to pull the head again to replace the bad silicone gasket.
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Old 06-16-2019, 10:28 PM   #29
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Default Re: I think my exhaust valves are burnt

I have been busy doing other stuff so this has been a slow project. I pulled the manifolds, distributer and the valve cover plate. I found the engine has modern style valves and all the clearances are between .010 -> .018 and the tappets are adjustable. I loosened all the head bolts and realized the head is stuck on tight so I am going to spray some penetrating oil around the studs and I have ordered a head puller that will be here in a couple of days. I will see what the valves look like as soon as I get the head off. I only expect to see one bad one because when I did a leak down test on the other cylinders the biggest problem I had was keeping the engine from spinning because the valves were pretty tight. I wonder what caused this problem.
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Old 06-17-2019, 04:46 AM   #30
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Default Re: I think my exhaust valves are burnt

Put the plugs back in and spin the starter over with the head nuts loose/off. Head should pop loose.
Or fill 1 cylinder with rope and turn it over by hand.
I'm guessing seeing you have modern valves,that the valve may be bent or the seat is bad.
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Old 06-21-2019, 12:28 AM   #31
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Default Re: I think my exhaust valves are burnt

I ordered a head puller from Snyder's and still could not move the head until I soaked all the studs with penetrating oil for a couple of days. I finally got it off and found a lot of carbon build up on various areas. Just wondering what the best way was to get all the carbon off and opinions on replacing all the studs. I think I can get the rust off them and the threads are still pretty good. I am worried about busting the studs off in the block if I try to replace them with new ones. Any opinions ?
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Old 06-21-2019, 04:29 AM   #32
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Default Re: I think my exhaust valves are burnt

Carburetor cleaner will soften up the carbon,then scrape it off. Look on YouTube.
Replace the studs and nuts and have the head checked for cracks and flatness.
Double nut the studs,they should come out.
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Old 06-29-2019, 09:53 PM   #33
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Default Re: I think my exhaust valves are burnt

I tried all kinds of options to clean the carbon and found that just soaking everything with good old WD40 and scraping a little got off the rust and most of the carbon. I sprayed the head with WD40 a couple of times and scrubbed it with one of those scotch pad kitchen scrubbing pads. I then took it out in the yard and sprayed the head with a hose to clean everything off and it looks almost brand new. New respect for WD40.
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The head bolts actually look pretty good so I decided to spray them with WD40 and run a nut up and down the threads to make sure they are clean. I am planning to use brand new head nuts because they are cheap and the old ones have some rust on them.
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I found the engine had been bored out to 3.975", but the bore is smooth and round and the engine was not burning a drop of oil so I am not going to touch it. If I ever have a problem I will just have it re-sleeved back to the original bore size.
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The 2 valves I am having a problem with were not really burnt, they look more like they were just poorly lapped in when they were installed. (Yes, it has hardened seats.) I thought about just re-lapping the two valves, but they also wobble a little like the valve guides are worn, so I plan to replace them all and lap them in properly.
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Will report progress....
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Old 06-30-2019, 11:47 AM   #34
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Default Re: I think my exhaust valves are burnt

If the bolts are old, have not been replaced for a long, may want to replace them with grade 8 with new nuts. Since the head is off, now would be a good time.
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Old 07-01-2019, 12:57 AM   #35
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Default Re: I think my exhaust valves are burnt

I keep thinking about replacing the studs, but I fear breaking one or more off in the block if I try to replace them. I know it is the right thing to do, but I had a couple of bad experiences years ago and I guess I still have not gotten over that fear.
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