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Thread: My horn is still great... but my carburetor isn't!

  1. #21
    Senior Member TJones's Avatar
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    Quote Originally Posted by Mark J View Post
    I think I found the problem...

    Should I start a new thread for all the questions I may have? Or change my original title to "Not a carb but a valve!" ?
    Or just keep it going here?
    I've already got questions, but watching a YouTube video first before I start whining...
    Just keep it here Mark
    Like CJ said your lucky it was just a little piece, if it was much bigger it would of probably had a “scrap iron fit”.
    The Seniors will give you some fix it ideas!!!!

  2. #22
    Super Moderator gmwillys's Avatar
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    Not an uncommon issue. A new set of Stainless valves will cure that. A piece of advice though, I would look to have hardened seats installed. This isn't mandatory, but if you do, you will not need to add a lead substitute to the fuel to act as a cushion for the valve against the seat.

  3. #23
    Super Moderator LarrBeard's Avatar
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    Concur with new valves and seats.

    While we are often tempted to do "just enough" to get a Jeep running again, I wish I had a dollar for every time I've thought or said ; "I wish I'd fixed xxxx while I had that engine apart last time".

    You have the head off, you are going to have all the tools you need to pull a valve (or eight of them) so I would suggest you replace the set while you're in there. That seat is going to be pretty badly eroded, so replacing it and it's brothers with hardened seats is the right way to do the job. You'll never wonder if lead-free gas is eating away at the seats and it's about to start acting up again.

  4. #24
    Super Moderator bmorgil's Avatar
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    I don't think you will find a machine shop that is going to fix just one. Its off to the shop for a valve job. I would agree with gm, a new set of hardened seats and some stainless valves and new springs and its ready to go. Resist the urge to reuse the springs. They will eventually break in their lifetime and you never know when. Cheap insurance, always use new springs. On an overhead valve engine a broken spring usually means piston to valve contact which can ruin the whole engine.

    That's going to be a big job. You will have to pull the motor down to correctly fix the exhaust seat. I just can't see a good job being done with the engine assembled.
    Last edited by bmorgil; 05-12-2021 at 08:40 AM.

  5. #25
    Member Mark J's Avatar
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    Well sh*t!
    I mean that in a "thank you" way for you guys, for waking me up.
    What I had planned on doing was just the single valve myself, with a great looking used valve I had, new spring, seats etc.
    My next question was "Can I get away with doing the exhaust valves?" but I think that's likely a dumb question. So I won't ask!

  6. #26
    Super Moderator bmorgil's Avatar
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    No such thing as a dumb question, and I will tell you I have read stories. I have read of a person who was going to do one valve in an assembled engine. There are tools out there to do it. I would say the condition of the rest of the valves wont be far behind the one that failed. If you were just looking to prove you could get it running for minimal cost for a short period of time, you might be able to get it done. It would be "less than optimal".

    I would say find a local machine shop. Go down and visit when their not busy. Tell them and show them what happened and ask them to show you an example of how that problem is fixed. The experience should help you understand what is needed.

  7. #27
    Super Moderator LarrBeard's Avatar
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    ' but I think that's likely a dumb question"

    I can think of a couple of "dumb" questions I didn't ask that ended up costing me dearly.

  8. #28
    Super Moderator gmwillys's Avatar
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    Story time in regards to Farmer's logic;

    Our '46 has been around the family since the early '80s. When purchased, it was used in the early evening to fog for mosquitos, but not with a sprayer rig or anything of the sort. Maintaining the Heep consisted in checking the fuel and filling the oil. Once in a while we would spring for a new set of chainsaw spark plugs. After a couple of years, the Heep was parked in the corner of the garage and transformed into a workbench/catch all, all due to it's thirst for oil. Long story short, in comes my Grandfather who was recently retired from the rat race, but still farmed 80 acres. He would visit our home place and look at the sad headlights of the heep looking out from under a pile of crap. A deal was made to dig the Jeep out and deliver it to the farm for Grandpa to use for his chores. Grand dad was a mechanical genius, but lacked any formal education except for the one earned from the school of hard knocks. He set forth on a mission to stop up the smog pump. He tore the head off to discover that the #3 piston was burnt, and had a hole in the center. The machine shop in town sold him one piston, a full set of rods and main bearings, and a gasket kit. Thirty years later, the engine still runs well, doesn't smoke up the ranch, and makes frequent trips to town to gather parts.

  9. #29
    Super Moderator bmorgil's Avatar
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    Every now and then gm! It sounds like Grampa had plenty of smarts to know if the compression was still there in three cylinders, and the cylinder was still in good shape, why not. Back in the day this is how we saved money for sure. If the bore hones out well and isn't beyond spec for oversize, it will work. If you tore it down and the other 3 pistons and bores were good, with a quick hone job its a ring set and valve job away from a rebuild.

  10. #30
    Member Mark J's Avatar
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    Love that story!!! Thank you.

    Soooooo, believe it or not, I did rebuild an F head about 40 years ago. It lasted a year, then did that major "blow up" I discussed earlier.
    I do remember what is required for a valve job, I think! I've watched a video already on removal of the valves/springs, etc. And luckily I have some very smart friends that have overhauled many engines to assist me if needed with lapping, etc.
    I'm still trying to decide though on doing the intake valves. I would love to just get away with doing all exhaust valves and take the chance on the intakes. I will, of course, inspect them and look for any obvious issues. I can be persuaded though by you guys. Now that I've pulled the head off, I realize how relatively easy it is, and NOT to forget that dang bolt where the carburetor sits. Oh, and to pull the push rods out too. Yes I had the head 6 inches off and it "stuck." Doh!!!
    I'm ok with having to pull the head again at a future date, hopefully a very future date.

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