Ford 3000 Valve Adjustment Problem

Good morning,
I just completed a ring job and valve job on my "67 Ford 3000 gas tractor. After I reassembled it, with all new gaskets of course, I checked the compression before adjusting the valve clearance just to make sure things were sealing properly. I got 140-150-155 for readings, a lot better than the 60-105-75 before. Then I preceded to adjust the valves as per the manual. When I was done adjusting the intake to .017 and the exhaust .021, I checked compression again (I checked compression because I thought it was odd that my tractor had about .060 of valve clearance and therefore I had to take up a lot) and adjusting my valves the compression dropped down 95-100 psi in all cylinders, I have two gauges and they both were giving the same reading. If I back off the adjusting nut by 1/2 turn I can get my compression right back up to the 150 range. The valves do open and close at that greater clearance. Any thoughts? I am thinking I may run it with more clearance.

sounds like your doing it right, since you do have compression. too tight and you would have a valve stay open and leak, and then burn its edge..

compression readings are varible based on a lot of things. if you do not have the throttle at wide open why your testing, you will read lower. If your starter slows a bit due to more cam loads it will read lower.

with larger valve lash you might be seeing the engine crank a bit faster and therefore show more compression. make sure you have a charger on the battery and the throttle wide open when you run your test. good luck.. bill

The intake and exhaust manifolds are both off the tractor so there is very little restriction. I was thinking camshaft load too but I only have to back off on the adjustment on one cylinder to get the compression to shoot back up to 150. If it were bogging down the starter it should only go up a third (roughly) higher than when all valves are "properly" adjusted.

valve timing??

are your sure the cam is in time with the crank shaft?? as in,, are you a tooth off the mark?? when you loosen up the valve, your delaying the valve opening but also making it close earlier and compression inproves, and it makes me wonder if your a tooth early or late on the cam??

are you using the right feeler guage??

I'm running out of guesss.. Bill

ok.. lets say your two teeth off??? theres a 3 cyl mark and a 4 cyl mark if i remember correctly.. which did you use?

DON'T run it with excessive valve clearance. You are just asking to tear things up in the valvetrain from the extra pounding.

Better check the cam timing AGAIN.

Thanks for the suggestions. I did not touch the cam at all, in fact the engine had never been opened up since it left the factory (I am only the second owner and I know the first owner well). I checked my feeler gauges, just bought the new set last week, with a micrometer and they are spot on. I had to do about two full rotations of the adjusting nuts to get them down to the right clearance, I figured the new valves were slightly shorter than the old ones. If I back off 1/4 turn to about .030 clearance I jump from 100 to 150 psi. The tractor ran well before the "operation" but it was getting a little hard to start and there was some blowby but it had power and ran well. I see no way the cam could be off time because it was running and not making any weird noises. Maybe the IT manual is giving my the wrong clearance. It says .017 and .021 (intake/exhaust) anyone have a Ford manual to check?

What really counts is the compression when the engine is at operating temperature. My guess is the cold lash settings you are using will give you the correct setting when the engine is at operating temperature. Leave them where they are at and then check them after an hour of running.

Some tractors(like my TO-30 Ferguson) provide a cold setting (0.015") and a hot setting (0.013") and you set the hot running after a warm up at as slow an idle as you can run to minimize oil splash.

I have found that the valve lash on these 3 cyl Fords are hard to set. Dunno why. I've been playing with valves on Ramblers, VWs, Triumphs, Yamahas, Budas, Hurcules and whatever else for most of my life and never had the problems setting the lash on them like I have on these Fords. It took me about 4 times to get my 3000 right. Finally I just went by the old addage that "it's better to hear them than smell them."
Mine still have a slight tick to them.
Good luck

I haven't checked the valve specs for a gasoline engine, but I thought they were the same as the diesel which are .015" Intake and .018" for the exhaust.
I can see the exhaust being a bit more on the gasoline engine, but certainly no more than 21.

I'd guess that if you're getting a lower spec with the correct clearance, then mabey your adjustment procedure is off somewhat. I don't check the marks on the diesels. I just watch the valves and get it near TDC by feel. You could pull the plugs and use a welding rod to determine when you're at TDC for adjustment purposes.

Another thought is that if you had slack valves, you may have rockers that are oddly worn or cupped. The consequence is that you can run your 1/2" wide feeler gauge measures the FLAT spots on your rocker and valve stem while the actual clearance is measured on the worn cupped part... which is sometimes substantially more. If I wanted to check that I'd set up a dial indicator on the rocker head over the valve and measure the actual clearance when you work the rocker back and forth.
If you find it excessive you could run the rockers down to spec... but you really should have them reground flat. Just a thought....
Dunno what to tell you beyond that.

Rod

I will have to check it out with my dial indicator tomorrow. But I can tell you that the rockers looked absolutely perfect and even the rocker arm to rocker shaft clearance was perfect. Mind you this tractor only has about 1600 hours, hourmeter stopped working last year at 1538 hours. I am starting to wonder if maybe Ford machined something with the camshaft keyway wrong, may a degree or two off. My manual does say .017 intake cold and .021 exhaust cold. I will probably try running it at "correct" clearance and see how it starts and runs.