308 woes

harry54
harry54 Senior Contributor
edited November -1 in HUDSON
My Hornet 308 finaly gave it's bad #3 valves the boot. I think it might be time to do a rebuild. My question is, I have 100 psi over 5 cylinders... the 6th is reading 75. That must be where my valve issues are.... Am I better served trying to fix the valves of the bad cylnder ? The motor is already 40 over.... How safe is 60 over ? Thanks for your thoughts......



Is it possible that 60 over would cause cooling issues ?

Comments

  • [Deleted User]
    [Deleted User]
    If you are just having valve problems why are you thinking of boring the engine? Pull the head and valve cover(s) and do a valve job and button it back up. An engine does NOT have to be bored every time it is disassembled. On the other hand if the cylinders are slightly worn you may want to go to oversize rings.
  • [Deleted User]
    [Deleted User]
    harry54 wrote:
    My Hornet 308 finaly gave it's bad #3 valves the boot. I think it might be time to do a rebuild. My question is, I have 100 psi over 5 cylinders... the 6th is reading 75. That must be where my valve issues are.... Am I better served trying to fix the valves of the bad cylnder ? The motor is already 40 over.... How safe is 60 over ? Thanks for your thoughts......



    Is it possible that 60 over would cause cooling issues ?
    If you can do just a valve job, go that way. If you do not burn oil then do not touch the motor. As far as boring, my engine is 60 over and has traveled 118,000 miles so far and still runs strong. You can bore a Hornet engine 100 over and no worries. Walt.
  • 7XPacemaker
    7XPacemaker Senior Contributor
    Walt is dead on.............
  • Unknown
    Unknown
    Dont Use The Word Dead When Talking About Us Older Folks, Lol, Bill Albright
  • SuperDave
    SuperDave Senior Contributor
    walt's garage-53 wrote:
    If you can do just a valve job, go that way. If you do not burn oil then do not touch the motor. As far as boring, my engine is 60 over and has traveled 118,000 miles so far and still runs strong. You can bore a Hornet engine 100 over and no worries. Walt.



    I agree Walt. I sold someone a 308 that turned out to be a .080 but didn't need anything. You would think I had sold them a time bomb! These are hard blocks and can endure lotsa miles.
  • harry54
    harry54 Senior Contributor
    SuperDave wrote:
    I agree Walt. I sold someone a 308 that turned out to be a .080 but didn't need anything. You would think I had sold them a time bomb! These are hard blocks and can endure lotsa miles.



    The motor uses some oil... maybe 1 qt every 500 miles or so. 30,000 miles ago i replaced a piston as it looked like it was slapping slightly... Back then I also adjusted the valves which brought the compression up to 100 across the board. My guess is that I leak oil as much as i burn.. All that being said... the motor just before this latest problem, had plenty of get up and go... The only issue it had was a crummy idle as the valves were always living on borrowed time... Will a valve job clean up the idle ? The other question I have is overall compression... Should n't this motor be at 120 psi ? Thanks for your thoughts...
  • [Deleted User]
    [Deleted User]
    bill a wrote:
    Dont Use The Word Dead When Talking About Us Older Folks, Lol, Bill Albright
    I agree with you Bill, we do not have to hear the word DEAD, for at our age we have one foot in the grave and the other on a banana skin.
  • mars55
    mars55 Senior Contributor
    harry54 wrote:
    Will a valve job clean up the idle ? The other question I have is overall compression... Should n't this motor be at 120 psi ? Thanks for your thoughts...



    Yes doing a valve job will clear up the idle. Having a difference of 25 psi between cylinders will cause a rough idle.



    The Hudson Shop Manual gives 100 psi as minimum value for cylinder compression.



    You should remove the cylinder head and inspect the valves and measure the cylinder wear in each cylinder.
  • SuperDave
    SuperDave Senior Contributor
    mars55 wrote:
    Yes doing a valve job will clear up the idle. Having a difference of 25 psi between cylinders will cause a rough idle.



    The Hudson Shop Manual gives 100 psi as minimum value for cylinder compression.



    You should remove the cylinder head and inspect the valves and measure the cylinder wear in each cylinder.



    Just as a point of reference on compression. A fresh 308 .040 bore with about ten minutes running time on it had 125 Lbs all six with a twelve volt boost. I suppose it would gain a bit as the rings seat. Subtract a little for 6 volts..And yes.. Idle WILL be a factor if compression is uneven.:)
  • harry54
    harry54 Senior Contributor
    SuperDave wrote:
    Just as a point of reference on compression. A fresh 308 .040 bore with about ten minutes running time on it had 125 Lbs all six with a twelve volt boost. I suppose it would gain a bit as the rings seat. Subtract a little for 6 volts..And yes.. Idle WILL be a factor if compression is uneven.:)



    So 100 psi across the board is telling you you don't have much to go before rebuild anyway.... ????
  • [Deleted User]
    [Deleted User]
    100 Ibs on the cylinders will be fine. Pop the head fix the valve button it up and drive it like you stole it then rebuild it if necessary.
  • SuperDave
    SuperDave Senior Contributor
    51hornetA wrote:
    100 Ibs on the cylinders will be fine. Pop the head fix the valve button it up and drive it like you stole it then rebuild it if necessary.



    Thats what I would do.:D
  • Hudson Grandpa
    Hudson Grandpa Expert Adviser
    This is basically is a question for Bill A, but others can chime in. This is my 308 Hornet 2 door bought from Bill A. over the years I baby an engine. When it's cold on starting it idles a little rough but then smoothes out as heat builds. When not quite warm it smokes but I can't tell when driving wether it's coming out of the oil pipe or the exhust pipe. Exhaust pipe has black soot on it. When I baby it on the road it smokes. When I stick my foot in the carb the smoke quits.

    I have been told I have some sticky valves. Other than that the engine runs and idles great, and only burns some oil. Spark plugs have black residue. Worst one is #3. Seems to have oil not on the tip, but on the threads a little. I know this sounds ridiculous but I have an extra set of plugs, and I change out about every 4 months, cleaning the old ones to be ready for replacement. See I told you I baby and engine....



    How close am I to a valve job?
  • harry54
    harry54 Senior Contributor
    Just an update.... Turns out that I had a cracked #3 exhaust .. all the valves are shot... Going to do a valve job.... All parts from Dale Cooper.. Thanks for the advice... bottom end looks ok..
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