Valve guides

Guy Johnson · #1 (**permalink**) 08-05-2006, 11:27 AM

How do I test to see if my valve guides are bad?

Guy

Scufty · #2 (**permalink**) 08-05-2006, 11:50 AM

shouldnt have any play at all, I just did mine ...brass so they should fit tight ...the brass wears

Excaliber · #3 (**permalink**) 08-05-2006, 12:12 PM

The technical way is to actually measure the valve stem and the inside of the guide. Of course few of us have the tools to do this. The clearance required is very small indeed, but the valve should move freely up and down in the guide and not 'wobble' around. Remove the valve springs to get a 'feel' for it. If in doubt, your off to the machine shop to have it verified.

Guy Johnson · #4 (**permalink**) 08-05-2006, 12:23 PM

I need to check the valve guide for leaks.

Guy

Excaliber · #5 (**permalink**) 08-05-2006, 12:25 PM

Leaks are usually caused by the valve stem seal that sits atop the guide. I don't know how you would check the 'leakage' of a valve guide, interesting question!

Woodz428 · #6 (**permalink**) 08-05-2006, 03:25 PM

Although I have never done it, I would imagine that you could pressure test like on a leakdown, but with the valves open. You would need to block off the carb flange and the exhaust with the valve covers off, but you could detect any leakage. I'm not sure it would be of any value since you wouldn't have a clue as to HOW much it was compared to a good one.

undy · #7 (**permalink**) 08-05-2006, 07:51 PM

Pick a cylinder and bring the piston up to top dead center. Pressurize the cylinder with LP air. Make sure you don't drive the piston back down in the bore, "locking" the crank if necessary. Using an "on the engine" spring compressor, pull the retainer/locks on both valves. Pull the springs, intake and exhaust. Let the air pressure of the cylinder. Note: with the piston up on TDC the valves can't drop much. Grip the ends on both valves and move them up and down in the guides while wiggling them right and left, front and back. If there's slop in the guides you'll feel it. If you can "feel" it then it's excessive. With a dial indicator you can get exact readings.. The whole process just takes several minutes.

Dave

Carnut427 · #8 (**permalink**) 08-05-2006, 10:42 PM

Yeah, like Undy said.

Excaliber · #9 (**permalink**) 08-06-2006, 11:00 AM

Heres one way to remove the valve springs with air pressure in the cylinder.

Carnut427 · #10 (**permalink**) 08-06-2006, 06:30 PM

GREAT, JUST GREAT! How'd you get that picture??? That's all I need, paparazzi taking pictures in my garage of my 'secrets'...



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