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Cylinder Head Issue
https://slantsix.org/forum/viewtopic.php?t=19692		 Page 1 of 1
Author:  Solotime [ Thu Sep 14, 2006 5:55 pm ]
Post subject:  Cylinder Head Issue
81 Dodge Ram 150 with the lean burn system still there, a shot carb well as other minor issues I can deal with but here's my problem. I removed the cylinder head because I suspected a valve problem due to what I was hearing from the motor. After removal I found the #3 cylinder exhaust valve badly burned with a small chunk melted away. After removing the valve I discovered a clear "crack" in the seat in about the same location as the missing part of the valve. I have no history on the truck as I purchased it a few months ago. However the head has pretty fresh paint and when I bought the truck it had a severely melted exhaust valve sitting in the ashtray. So my question is...could the crack be the cause of the valve getting burned or is it more likely that the crack occured when the valve went bad? Secondly, can this be repaired or is it time to find another head?
Thanks
Author:  LUCKY13 [ Fri Sep 15, 2006 4:37 am ]
Post subject: 
It is very possible the crack is what caused the valve to burn. If it is a hardend seat that is cracked it probably can be fixed, just be sure they check to see if the head is cracked when they cut the seat out. You machine shop will be able to awnser the question on if it can be fixed better than I can so you may as well let them look at it and see what they say.



Jess
Author:  slantzilla [ Fri Sep 15, 2006 7:54 am ]
Post subject: 
Yep, I would guess they just dropped a valve into the cracked seat and sold the truck. :shock:
Author:  mpgmike [ Tue Sep 19, 2006 1:20 pm ]
Post subject: 
Quote:
It is very possible the crack is what caused the valve to burn. If it is a hardend seat that is cracked it probably can be fixed, just be sure they check to see if the head is cracked when they cut the seat out. You machine shop will be able to awnser the question on if it can be fixed better than I can so you may as well let them look at it and see what they say.

Jess
It's quite possible the head is an older pre-74 that doesn't have the hardened seats. Hardened seats can be installed by cutting away some material and pressing them in. It is reported that there are coolant jackets nearby, so care must be taken to not ruin the whole head.

Mike
Author:  argentina-slantsixer [ Tue Sep 19, 2006 2:27 pm ]
Post subject: 
sorry to hijack partially... has anyone running 1.44 exhaust valves installed hardened seats? one machine shop told me that they would hit the water... :?
Author:  slantzilla [ Tue Sep 19, 2006 2:37 pm ]
Post subject: 
Quote:
sorry to hijack partially... has anyone running 1.44 exhaust valves installed hardened seats? one machine shop told me that they would hit the water... :?
I would be less worried about hitting water than I would about having a seat fall out. By the time you cut the seats into the head and then machine them for OS valves, and then cut them to match the pocket porting for the OS valves, you got nothin' left. :shock:
Author:  argentina-slantsixer [ Tue Sep 19, 2006 2:58 pm ]
Post subject: 
Quote:
Quote:
sorry to hijack partially... has anyone running 1.44 exhaust valves installed hardened seats? one machine shop told me that they would hit the water... :?
I would be less worried about hitting water than I would about having a seat fall out. By the time you cut the seats into the head and then machine them for OS valves, and then cut them to match the pocket porting for the OS valves, you got nothin' left. :shock:
so I go with no hardened seats (inserts) as with your recipe for pistons (get the bigger size possible) and if I burn a seat I just throw the head in the trash... makes sense... anyway lots'a stupid folks down here has started to yank out good slant six cores and put in 340's and 318's.... right? BTW I run holleys... :) no chance of BBD'ing a exhaust valve out. :twisted: :twisted: :twisted: :roll:
Author:  slantzilla [ Tue Sep 19, 2006 3:14 pm ]
Post subject: 
Hardened seats are not nearly as critical as some would be lead to believe. :shock:
Author:  emsvitil [ Tue Sep 19, 2006 5:12 pm ]
Post subject: 
Is there a way to duplicate the factory method of hardening the seat area without machining in the hardened seats??????????
Author:  SlantSixDan [ Tue Sep 19, 2006 9:20 pm ]
Post subject: 
Quote:
Is there a way to duplicate the factory method of hardening the seat area without machining in the hardened seats?
No, not practicably.

And, I would say that it is not a good idea to build a head without putting in hard exhaust seats. No, they aren't as critical on a stock slant-6 as they are on some other applications, but especially with oversize valves, unleaded gasoline will cause erosion sooner than later if no hard seat is used.
Author:  Solotime [ Wed Sep 20, 2006 5:38 am ]
Post subject: 
If I can steal my post back for a moment! J/K
I pulled the rest of the engine out and it's pretty wore out. I can actually push the piston over to one side of the cylinder and see the rings. There is also a sharp and deep groove around the top of the cylinder. At 212K miles I'm guessing the engine had not been touched other than the previously mentioned cylinder head repair. I do beleive also that the head is the original '81 head. The main and rod bearings look very good with no scoring or obvious problems. So I am going to just do a complete rebuild on the engine. So I will post a new thread later about what path I should take with it.
Thanks guys.
Edwin
Author:  argentina-slantsixer [ Wed Sep 20, 2006 7:36 am ]
Post subject: 
Sorry Edwin, I promisse I won't ask nothing on your engine rebuild topic! :wink:

yep, sounds like it needs a complete rebuild... good thing that the mains are OK... how about the connecting rod journals?
Author:  Solotime [ Wed Sep 20, 2006 10:09 am ]
Post subject: 
All the journals look very good
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