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  1. #11
    PWCToday.com Is My Home Away From Home AC 46's Avatar
    Join Date
    Apr 2010
    SE CT

    Re: Valve shim measuring onfx140

    Quote Originally Posted by Evilslywalker20 View Post
    I've never done this before, but you are saying install them and then measure.. do you mean torque down the cams and gen measure the gap between the lobes without the shims inside the bucket? And if so what side do you measure ?
    No you need to install the shims.Make a chart, record the clearances and juggle the shims according to what is needed
    R.I.P. Super Sic

  2. #12
    PWCToday Guru
    Join Date
    Oct 2013

    Re: Valve shim measuring onfx140

    ...not sure what that post above says....

    I have not worked on your specific engine. Back in the 60's, (I have been at this a long time) Homelite introduced the first 4 cycle outboard. They used this system to set valve clearance. It was actually a Crosley auto engine turned up so the crankshaft was vertical. (http://crosleyautoclub.com/EngineTre...ng_Tree-4.html)

    BEFORE you do anything, use a micrometer to measure each shim to be sure the size printed on it is correct!!!! If you do not have a micrometer you need get one, or a good digital caliper. You also need a good feeler gauge.

    Make a grid on a sheet of paper or a spreadsheet with cells to record; valve number, current shim size, current clearance value, required clearance value, required shim size.

    Install the the shims, and the cam just like you normally would, Do not worry about the which goes where. EXCEPT, record where you put them. Maybe put them in numerical order from small to large. Torque everything as it is supposed to be. Then measure and RECORD the clearance between the cam and the follower at each location(high spot on the cam opposite where you measure). Then double check to be sure you got them correct.

    Unfortunately you have such a large range of sizes, you may very well have some locations that will have NO clearance when you first measure. You may need to do the procedure below a couple of times until you get them all back in the correct locations.

    After taking all of the measurements, you need to do some calculations to determine what size spacer you need in each location to get the correct clearance.

    The math looks like this. (Current Shim + Current Clearance - Desired Clearance = Required Shim)
    for example (.178 + .008 -.006 = .180) or perhaps (.178 + .002 - .006= .174)

    If you have any places where the clearance is ZERO, all you can do it use zero. (.178 + .000 - .006 =.172) Remember however that it is possible that the clearance was actually less than zero. So you will have to try the .172, and check the clearance again.

    After you have done these calculations remove the camshaft. Switch the spacers as required. Then reinstall, re-torque and recheck all of the clearances. It is a pain to do, but in reality is a very reliable way to set valve clearance.

    Also, depending on how far apart the engine was.... if the valves have been removed and put back into different holes, it is possible you may not have the shims you need to get them all correct. When I worked at a factory authorized dealer, we had a kit with the whole range of shims, so we could just swap them as needed. You may need to buy some new shims. If you have some shims that are too thick, If you are good and you are patient, you can use a sharpening stone to make them thinner. If you do this make sure you remove material from the side that has the size written on it and be sure you do not make it tapered.

    Good Luck,

    2, 1998 TS 770 L, restored and running great. (Except for the one with engine that SBT put the WRONG crankshaft bearing into and is now sitting as I collect repair parts)

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