So, the ...erm...."free" Ranchero continues its streak of somehow costing me more money that I had planned on spending ;-)
When I removed the head, I thought the valves actually looked pretty decent - the carbon / oil / etc on the back of the valve there was the worst of them, most were cleaner.
I removed everything and started cleaning up the head, and since I had the valves out, I decided to lap them before reinstalling. The lapping itself went fine, I even found an old hand crank tool for the job, and I got nice even and clean surfaces on the valve and seat, but.....I can't get number 5 intake or exhaust to seal. I started with #6, that went fine. But #5 fails the water test - it takes perhaps a few minutes, but after filling the chamber, both the exhaust and intake valves leak - and to varying degrees it seems, depending on how the valve is put in. I lapped both valves several times, perhaps some improvement, but overall they both still leak. I am concerned about "over lapping" so I only did three rounds each. Everything looks good in terms of the valve and seat surfaces, but obviously they are not right. I didn't have the springs installed for the leak test, but none of the videos I watched had springs installed, so I doubt that matters.
I am not an expert on heads - frankly I usually just buy a new one - but as far as I am aware, if you can't correct a leaky valve with lapping, you need a machine shop and a rebuild - pretty much your only option - right?
I also found this Remanufactured Cylinder Head for 1969-1974 Ford/Mercury
Its for a 250, has larger chambers (so lower compression) but bigger valves and maybe a larger carb bore - I'd prefer to use the stock 200 head I have, but if I can't get it rebuilt locally, perhaps this is an option .
When I removed the head, I thought the valves actually looked pretty decent - the carbon / oil / etc on the back of the valve there was the worst of them, most were cleaner.
I removed everything and started cleaning up the head, and since I had the valves out, I decided to lap them before reinstalling. The lapping itself went fine, I even found an old hand crank tool for the job, and I got nice even and clean surfaces on the valve and seat, but.....I can't get number 5 intake or exhaust to seal. I started with #6, that went fine. But #5 fails the water test - it takes perhaps a few minutes, but after filling the chamber, both the exhaust and intake valves leak - and to varying degrees it seems, depending on how the valve is put in. I lapped both valves several times, perhaps some improvement, but overall they both still leak. I am concerned about "over lapping" so I only did three rounds each. Everything looks good in terms of the valve and seat surfaces, but obviously they are not right. I didn't have the springs installed for the leak test, but none of the videos I watched had springs installed, so I doubt that matters.
I am not an expert on heads - frankly I usually just buy a new one - but as far as I am aware, if you can't correct a leaky valve with lapping, you need a machine shop and a rebuild - pretty much your only option - right?
I also found this Remanufactured Cylinder Head for 1969-1974 Ford/Mercury
Its for a 250, has larger chambers (so lower compression) but bigger valves and maybe a larger carb bore - I'd prefer to use the stock 200 head I have, but if I can't get it rebuilt locally, perhaps this is an option .
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