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    I am working on the Shores V4. I am having problems getting the valves sealed. I have tried lapping and that failed. Then i tried re-cutting the seats and then lapping and that failed. Then i tried to recut the valve, then lapp and that also failed. I'm not sure what to try next.

    How did you get your valves to seal?
    • CommentAuthorkamran
    • CommentTimeJun 18th 2009
    if the seats are not concentric then you will have problem. Put a dye around the valve seat and then very lightly lap the valve in. Then try to see if the dye all gone around the valve seat or some part still has the dye.
    I think the less contact area between valve-face and valve seat gives better sealing.

    How do you check for leak, and how bad is leaking?

    Have you tried cutting the valve/valve seat off by 1 or 2 degrees to eachother? Makes sealing much easier as the seal area will be smaller.

    Kamran also has a good point. Could be the bore in the valve cage is off just a little which will give you leak problems.

    Steve, your V4 build looks beautiful, great work! Best of luck.
    I wish I had more time for the shop but work and being a father of three sure keeps my hands full. :)

    Steve are your valve springs strong enought for the job?
    Have tried many things and have not find the final answer, something things to keep in mind:
    Keep the contact area ( seat circle) as small as possible, it is very difficult to seal a very wide area, if your seat in the valve cage is too big, try to re cut the internal deeper portion of the seat to let's say 30 (60 Inc) deg, and bring the seating circle closer to the valve head.
    Valve seat, assume they are cages ( valve guide and seat) are they concentric, any chatter marks, sometimes a countersink 90 deg single lip cutting can be used to clean the seat area, however try to keep the seat area small.
    Valve, are the seats free of chatter and concentric.
    Springs, try to use a spring of the same dimensions but a bigger size in the wire. use music wire springs instead of stainless steel springs.
    When seating the valves, use some grinding compound like Clover 280 grit, MAKE SURE to CLEAN several times the guides / valves once you are done, that stuff is very very bad.
    To test valve sealing, you can make a plate to cover the combustion area, providing means to pressurize the combustion chamber, i do use aluminum plate and apply about 50 psi, you can submerge in water and see where the air is coming out from ( I had problems once in the sealing of the cage and head and I blamed the valves)

    Hope this provide some ideas.

    best regards.
    • CommentAuthorkamran
    • CommentTimeJun 19th 2009
    As Jaime said, is a good idea if you can make the plate to cover the combustion area for testing, but I also found out in model engines, with the valve close, if you pure some acetone which has a very low viscosity into the intake or exhaust hole, and if it doesn’t leak through them your valve sealing is good.
    I made the cages in one setup so the OD, ID, and valve guide bore should be concentric.

    I cut the valves using the exact same angle before resetting the angle on the compound slide.

    The valve seat area is about .020 wide

    I made a 4 flute cutter to recut the seats. They are chatter free.

    The springs are being used on Bob's Peewee without trouble.

    I did make a fixture so i could dunk the head under water.

    I tried some die and could see a bronze ring but it is hard to tell with 1/4 inch valves.

    Maybe I should just press the cages out and start over with 12L14 cages. Then i could cut the seats after they are in the head.
    Can you increase the spring diameter one size i.e from 0.2600 to 0.3200 in the same spring configuration, I did that recently to bench run my Mastiff, had one leaky exhaust in one side and one leaky intake in the other bank ( 4 cyl horizontal) after a couple of run in periods I was able to replace them with the smaller diameter springs, no leaks and engine is running smoother now.

    • CommentAuthorjay rich
    • CommentTimeJun 20th 2009 edited
    steve stick with brass cages try this do not cut the vale seat at all in the brass cage first make the valves at a 45 degree angle so it has a wide face to seat then die the valve and seat twist the seat in one direction and the valve the outher then check the cage and valve to see your high and low spots and if you have to recut the valve face just glace it and re seat it if its realy close or you get a shadow of a full valve seat ring cut your valve cage up high re die then and check it should seat your lucky 1/4 valves are big to me try 1/8 it will drive ya nuts and just for giggles get a o ring and put this on the valve stem and place the valve in the cage and see if your valve will seat and seal i tried this and ran the sidewinder engine on nitro ran great till the o ring vavle seals went bye bye ....jay
    Steve........Have you solved your valve problems yet ???????? UD

    I made a new set of cages from drill rod. Things were better but not solved. I decided to step away and work on other projects and then get back to it later.

    I'm going to try to press the cages in and then cut the seats with a seat tool. This way i can make the seats very thin.

    We will get it!!

    I did make a furnace for melting aluminum and i have been making BIG progress on a CNC milling machine.
    I had valve leakage on my Little Hercules too.
    It took over 15days to solve that problem.
    I tried to lap again and again, but failed.
    At last I found that the leakage was not cause by the impairment of the valve seat but
    caused by the short pass form outside of the valve guide to intake port.
    Only one drop of LOCTITE solved the problem.
    I wrote about it on my web.
    (sorry only Japanese but you can see the photo about it)

    If it becomes your help, I will be happy.