No helicoil, just some thread sealant.
CK5
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Help diagnose engine problem...
- Thread starter Keitha
- Start date
If all the exhaust valves are galled your machinist did not give proper clearance on the exhaust guides when he rebuilt the heads. Sounds to me like he is trying to convince you this is your problem and not his. 
Another thing, oil would get pulled into the guide only on the intake side, the exhaust side would want to push oil away from the valve/guide. Have your machinist pull all the intake valves and check them for galling also, i'll bet there isn't any on the intakes.
Another thing, oil would get pulled into the guide only on the intake side, the exhaust side would want to push oil away from the valve/guide. Have your machinist pull all the intake valves and check them for galling also, i'll bet there isn't any on the intakes.
If all the exhaust valves are galled your machinist did not give proper clearance on the exhaust guides when he rebuilt the heads. Sounds to me like he is trying to convince you this is your problem and not his.
Another thing, oil would get pulled into the guide only on the intake side, the exhaust side would want to push oil away from the valve/guide. Have your machinist pull all the intake valves and check them for galling also, i'll bet there isn't any on the intakes.
Could you explain about the valve guide clearance? I thought the valve stems/guides were a standard diameter.
Chevy valves measure anywhere between .341-.343" and the clearance needs to be correct otherwise a guide which is too tight will sieze a valve in it. i typcally like to have .0015" on the exhaust and .001" on the intake. If the engine is going into an application where it will be worked hard then i like to have .002" clearance on the exhaust side. The intake valve and guide always run cooler than the exhaust since there is a cool air/fuel charge entering the intake port whereas the exhaust runs hotter because of the combustion temps leaving the port.
Thanks for the explanation 4x4High.
Yeah, Right, you somehow pumped so much gas into that engine that it washed the oil out of the EXHAUST valve guide!!
When is the exhaust valve stem ever going to see any fuel?
Its closed when there is fuel vapor in the cylinder. After the plug fires, all the fuel is going to burn. If its running rich, a lot of it will not get burned completely and will exit as carbon.
If you could somehow get enough fuel in there so that there was liquid left after the cylinder fired, you would have melted the cat if it has one, or you would have raw gas or flames coming out the tailpipe.
Show of hands how many folks have killed the ignition briefly and then turned it back on to make the car shoot flames out the pipe and scare the neighbors<G>.
I've had to replace two mufflers because of doing that.
Anyway....there is a simple answer to him when he says too much fuel. Just look at the cylinder walls.
If they are nice and smooth, it has not run that rich. One of the first things to go when you get fuel washdown is the film between the rings and the cylinder walls.
I've seen a bad carb score the cylinder walls in less than 200 miles.
No, the only, and I mean ONLY out I might see for this guy is for him to claim that the engine produced so much carbon that it somehow worked its way up between the valve stems and guides and reduced the clearance.
Never seen it myself, and you would have had to have problems seeing out the rear view mirror for the black smoke.
The plain fact of the matter is, either the heads ran real hot for some reason, or he did not ream the guides enough after he replaced them.
Most cases, the valve guides are pressed in. Which causes them to shrink inside slightly. Plus most are made a little small anyway to allow for final machining.
After the guides are pressed in, the valve stem is mic'ed and then the guide is reamed out to a certain amount over that size to allow for expansion when it gets hot.
Even if the guides are supposed to be the correct size for the stems, a good shop will ALWAYS mic the hole and the stem to make sure.
Tell him to dig out his hole gauge and Micrometer, and give you the amount of clearance in the best hole, or several of the holes.
I don't know off the top of my head what the clearance should be for that head, but I'll bet someone on the forum will know.
I checked out his site. He sure has some nice machines there.
Fairly precise.
He does brag about holding things to .0001. Which is pretty good for engines.
Of course, on some of the machines I have to work on from time to time, .00005, or as its sometimes called, " a half of a tenth" is considered sloppy.
And the most important thing to remember about having a very precise machine, is that if you tell it wrong, it will F*ck something up very precisely.
And, if its computer controlled, it will do it again and again exactly the same way.
Great machines are no substitute for good machinists. Or Machinists that are paying attention to what they are doing.
J.
Dang it, screwed up the font size, sorry, I'll try to do better next time.
Aha!! got it right that time!!
[SIZE=+2] [/SIZE]
When is the exhaust valve stem ever going to see any fuel?
Its closed when there is fuel vapor in the cylinder. After the plug fires, all the fuel is going to burn. If its running rich, a lot of it will not get burned completely and will exit as carbon.
If you could somehow get enough fuel in there so that there was liquid left after the cylinder fired, you would have melted the cat if it has one, or you would have raw gas or flames coming out the tailpipe.
Show of hands how many folks have killed the ignition briefly and then turned it back on to make the car shoot flames out the pipe and scare the neighbors<G>.
I've had to replace two mufflers because of doing that.
Anyway....there is a simple answer to him when he says too much fuel. Just look at the cylinder walls.
If they are nice and smooth, it has not run that rich. One of the first things to go when you get fuel washdown is the film between the rings and the cylinder walls.
I've seen a bad carb score the cylinder walls in less than 200 miles.
No, the only, and I mean ONLY out I might see for this guy is for him to claim that the engine produced so much carbon that it somehow worked its way up between the valve stems and guides and reduced the clearance.
Never seen it myself, and you would have had to have problems seeing out the rear view mirror for the black smoke.
The plain fact of the matter is, either the heads ran real hot for some reason, or he did not ream the guides enough after he replaced them.
Most cases, the valve guides are pressed in. Which causes them to shrink inside slightly. Plus most are made a little small anyway to allow for final machining.
After the guides are pressed in, the valve stem is mic'ed and then the guide is reamed out to a certain amount over that size to allow for expansion when it gets hot.
Even if the guides are supposed to be the correct size for the stems, a good shop will ALWAYS mic the hole and the stem to make sure.
Tell him to dig out his hole gauge and Micrometer, and give you the amount of clearance in the best hole, or several of the holes.
I don't know off the top of my head what the clearance should be for that head, but I'll bet someone on the forum will know.
I checked out his site. He sure has some nice machines there.
Fairly precise.
He does brag about holding things to .0001. Which is pretty good for engines.
Of course, on some of the machines I have to work on from time to time, .00005, or as its sometimes called, " a half of a tenth" is considered sloppy.
And the most important thing to remember about having a very precise machine, is that if you tell it wrong, it will F*ck something up very precisely.
And, if its computer controlled, it will do it again and again exactly the same way.
Great machines are no substitute for good machinists. Or Machinists that are paying attention to what they are doing.
J.
Dang it, screwed up the font size, sorry, I'll try to do better next time.
Aha!! got it right that time!!
[SIZE=+2] [/SIZE]
Last edited:
Slapperbar
Retired Navy NDT Examiner
You can edit the post, highlight it and fix it.
Yep, knew I could, but first I had to figure out what the heck I did wrong, and then when I did, I had to experiment to get the right size font.
I think I nailed it that time.
Great info.
What do you guys recomend for Valve Seals?
What do you guys recomend for Valve Seals?
Stellite, they are hard and won't get beat in like any soft seat would.
Slapperbar
Retired Navy NDT Examiner
Stellite is harder than Woodpecker lips.
Are those the seats or Seals? I found info on Stellite valves, but not valve seals. I would like to "recomend" what components for the machinist to use.
What valve Seals? Umbrella or Positive? What material?
What valve Guides? Bronze? I was reading that bronze is good but should use a bit more clearence (.002" - .0025").
Sorry my bad, i thought you said seats.
Positive seals are always best and viton.
Stay with a cast guide (bronze wears out really quick and are more used with race car stuff)
Well I can not believe that it has been over 1 month, but I got the Suburban up and running today. New valves, guides, seals etc.
I have been traveling for work and I only really got to work on it on the weekends after my family priorities so it took a while.
So far so good, it sounds good and seems to run good. I installed Remflex header gaskets and my exhaust leak/tick is gone.
Now I have to get my WideBand O2 installed and get back to tunning this thing.
Thanks again for all the great help on this. You guys were right on all the way!
I have been traveling for work and I only really got to work on it on the weekends after my family priorities so it took a while.
So far so good, it sounds good and seems to run good. I installed Remflex header gaskets and my exhaust leak/tick is gone.
Now I have to get my WideBand O2 installed and get back to tunning this thing.
Thanks again for all the great help on this. You guys were right on all the way!
