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  1. #1
    Chief Petty Officer cajuncook1's Avatar
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    Default Needs some information about a Johnson 10hp QD-18

    Hey guys, got my eye on a 1957 10hp Johnson QD-18. Been reading some of the more recent and past post on these series of motors. A lot good information supplied.

    My biggest concern is compression numbers for this series.

    What is consider excellent, good, ok, and no way?

    The reason I like to ask you guys is because is because not all motors are the same and compression values vary with series and hp of motor.

    Example: compression for the 9.5hp Sportwin series because of the low impact starter is 60 to 80's compression is considered ok to good.(that is my general understanding)

    Any suggestions about compression numbers for QD-18 or any other advice would be awesome to get.

    Appreciate any suggestion guys!
    Being cheap and not getting a manual will cost you hundreds or maybe thousands of dollars

  2. #2
    Chief Petty Officer cajuncook1's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    bump
    Being cheap and not getting a manual will cost you hundreds or maybe thousands of dollars

  3. #3
    Vice Admiral 1946Zephyr's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    I think about the same would be good for the old QD-18 What's more important, is that the compression readings are within 10% of each other. I found it's best to take a compression test, once the motor has been running, that way the rings are all free and working the way they should be.
    Vice Admiral Zephyr

    1941 Johnson HD-20 (in restoration)
    1947 Sea King 5hp
    1948 Evinrude Sportsman
    1949 Martin "40"
    1951 Evinrude Fastwin
    1954 Evinrude Fleetwin
    1955 Evinrude Fleetwin
    1955 Johnson JW-11
    1955 Johnson CD-12 (2)
    1955 Johnson QD-16
    1955 Johnson RD-17
    1957 Jhnson CD-14
    1957 Evinrude Big Twin
    1958 Evinrude Fisherman
    1958 Johnson FDE-12
    1959 Johnson RDSL-21B
    1974 Tanaka 1hp (screamin' drink mixer )

  4. #4
    Chief Petty Officer cajuncook1's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    Thanks 1946Zephyr,

    Appreciate your input, but it looks like I will have to continue my search for 10hp motor. The guy wanted $250 for a motor that is not currently running, stated ran 10 years ago, compression about 75/75, tank(says its ok), and motor is in ok cosmetic condition. He stated when they ran it years ago, they ran it on 32:1 fuel ratio(should be 24:1). He was firm on the price, so my search continues.

    Again appreciate your input 1946Zephyr
    Being cheap and not getting a manual will cost you hundreds or maybe thousands of dollars

  5. #5
    Lieutenant Commander kbait's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    The most I'd pay for what you described is $125, and that'd be after I confirmed that the fuel primer on the tank was functional. You're likely looking at coils, points/condensers, carb kit, impeller.. possibly gearcase seals, prop hub may be weak, clutch dog may want to slip.. etc. You could be looking at quite a bit of money and TIME that could be spent fishing! If I found the motor you're looking at in demonstrated perfect running order, $300, maybe $400 w/tank.
    75/75 should be good. You can get different readings depending on how fast you spin it over..
    It's almost beyond the point of bearable how torturous it is to try to have any dignity in being a Vikings fan..

  6. #6
    Chief Petty Officer cajuncook1's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    Quote Originally Posted by kbait View Post
    The most I'd pay for what you described is $125, and that'd be after I confirmed that the fuel primer on the tank was functional. You're likely looking at coils, points/condensers, carb kit, impeller.. possibly gearcase seals, prop hub may be weak, clutch dog may want to slip.. etc. You could be looking at quite a bit of money and TIME that could be spent fishing! If I found the motor you're looking at in demonstrated perfect running order, $300, maybe $400 w/tank.
    75/75 should be good. You can get different readings depending on how fast you spin it over..
    Pretty much what I was thinking KBait. I offered him max $150 if the coils were good and I didn't even want the tank, but I guess he wanted more...oh well, I told him to call me if he reconsidered.

    Thanks for the information about the compression, I wasn't sure if that was low. Like I stated earlier, different motors, years and series have different compression requirements and I certainly don't know them all, so I usually ask to get some type confirmation or at least a consensus from a group of knowledgeable guys like you all.

    Thanks again for your input Kbait.....appreciate ya dude!!
    Being cheap and not getting a manual will cost you hundreds or maybe thousands of dollars

  7. #7
    Vice Admiral 1946Zephyr's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    Well, 32:1 isn't a bad thing for the old QD-18, eventhough it calls for 24:1 It sounds like the pistons and rings are in okay condition, since the compression is even. 75 psi on both isn't too bad. It should be in decent shape inside. These motors are fully jeweled, so no worries on the crank and rod assemblies. Many people are out there running these at 50:1 without issues, but if they should overheat the slightest bit, the pistons have a risk of scoring.

    For $250 though, I would want it running and ready to hit the water. I sell then for this price in top notch running condition and the buyer doesn't need to do anything to them, except rutine maintenance.
    Vice Admiral Zephyr

    1941 Johnson HD-20 (in restoration)
    1947 Sea King 5hp
    1948 Evinrude Sportsman
    1949 Martin "40"
    1951 Evinrude Fastwin
    1954 Evinrude Fleetwin
    1955 Evinrude Fleetwin
    1955 Johnson JW-11
    1955 Johnson CD-12 (2)
    1955 Johnson QD-16
    1955 Johnson RD-17
    1957 Jhnson CD-14
    1957 Evinrude Big Twin
    1958 Evinrude Fisherman
    1958 Johnson FDE-12
    1959 Johnson RDSL-21B
    1974 Tanaka 1hp (screamin' drink mixer )

  8. #8
    Vice Admiral samo_ott's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    75# a side is about the minimum I'd want. and for a QD18 untested I would not pay over $75 with the tank up here.

    And the QD18 is not fully jewelled as seen in the attached photo so don't go too lean on the oil...
    Attached Images Attached Images
    Steve.

  9. #9
    Chief Petty Officer cajuncook1's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    Thanks Sam_Ott and 1946Zephyr for further insight and information. I agree $250 is too much. Maybe I will email the owner in about a month and see if he wishes to reconsider a lower price. Unfortunately, the older motors are harder to find in my neck of the woods.

    Thanks!!!
    Being cheap and not getting a manual will cost you hundreds or maybe thousands of dollars

  10. #10
    Vice Admiral 1946Zephyr's Avatar
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    Default Re: Needs some information about a Johnson 10hp QD-18

    Quote Originally Posted by samo_ott View Post
    75# a side is about the minimum I'd want. and for a QD18 untested I would not pay over $75 with the tank up here.

    And the QD18 is not fully jewelled as seen in the attached photo so don't go too lean on the oil...
    Well.....with the exception of the wrist pin, which is all the better. The main thing is, the crank and rod bearings are. At least with the wrist pins being the old bushing type, you don't have the issue of needle bearings comin out and bouncing around in your crank case, like a lot of them have.

    I love the looks of mangled metal. No two particles look the same.
    Vice Admiral Zephyr

    1941 Johnson HD-20 (in restoration)
    1947 Sea King 5hp
    1948 Evinrude Sportsman
    1949 Martin "40"
    1951 Evinrude Fastwin
    1954 Evinrude Fleetwin
    1955 Evinrude Fleetwin
    1955 Johnson JW-11
    1955 Johnson CD-12 (2)
    1955 Johnson QD-16
    1955 Johnson RD-17
    1957 Jhnson CD-14
    1957 Evinrude Big Twin
    1958 Evinrude Fisherman
    1958 Johnson FDE-12
    1959 Johnson RDSL-21B
    1974 Tanaka 1hp (screamin' drink mixer )

  11. #11
    Supreme Mariner
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    Default Re: Needs some information about a Johnson 10hp QD-18

    Quote Originally Posted by 1946Zephyr View Post
    Well.....with the exception of the wrist pin, which is all the better. The main thing is, the crank and rod bearings are. At least with the wrist pins being the old bushing type, you don't have the issue of needle bearings comin out and bouncing around in your crank case, like a lot of them have.

    I love the looks of mangled metal. No two particles look the same.
    See, the problem is, the 10hp motors, pre-1961 are notorious for beating the wrist pins loose in the pistons. 1961-63 got the same wrist pin roller bearings as the big motors. For the older ones, I think they need all the help (oil) they can get. And I'm not so sure even that will help.

  12. #12
    Seaman
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    Default Re: Needs some information about a Johnson 10hp QD-18

    Mine gets about 70 on the compression test. I paid $75 for mine and have about $200 in it. The tank is important as the new tanks don't work.

    Frank

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