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Showing results for tags 'exhaust valve'.
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I picked up my 1974 C160 Auto about a year ago and got it running this spring. The PO said he bought it to restore, put it in the barn and never got to it. So after cleaning fuel system and changing engine and Sundstrand black slug oil it came to life. I’ve added the seat, temporary muffler and 2nd hydraulic valve. Tranny is strong and engine ran good at idle but would backfire every couple of minutes at 1/2 or more throttle New Plug was black quickly so I leaned it out but it would then bog down under load. So I decided it was tune up time. New points installed and adjusted using ohm meter came out to 0.18. Opened the carb and someone had taken taken a screw driver to the main jet and it was shot so I ordered an aftermarket carb. While I waited for the carb I pulled head to decarbon and since carb was off good time to check valve adjustment, all was good so I put it back together and no improvement. ive been wanting a Cylinder Leakage Tester and my Oreilly store made me a good match sales price. I hooked it up..... . At 50 psi input I had 9 ypsi leakage or 20% which is to much. I found I had excessive exhaust valve leakage and some cylinder leakage back into the crankcase. The intake valve seems to be sealing good 😀 Rechecked valve stem to lifter clearance and exhaust had 0.017 and intake 0.007 clearance, right on spec. I re pulled the head and exhaust valve. I lapped valve some more then checked it with machinist prussian blue and have a good 0.60 this or more sealing contact.. I also took a new exhaust valve and checked contact and it was good I checked valve stem size and it is worn but still in spec. I put exhaust valve and spring back in and sprayed some wd40 around the top of the valve and it did not leak through. I put head back on and retested and still have the same exhaust leakage I’m at a loss, what am I missing
