Oh Mighty Forum, what are the secrets to keeping one's sanity while lapping valves with the standard suction cup tool method??? I've tried cleaning the cup and valve surface with dry cloth, with alcohol, and with glass cleaner. All result in the same basic failure mode: I can back-forth rotate the tool for about 2 seconds and then 'poof!' the suction breaks and I have to start over. Once in a while I can just stick the suction cup back onto the valve surface and continue for another 2 seconds. What are the secrets of the gods???

You have a weak coil spring holding the valve above the seat, right?

I took a piece of fuel line that was big enough to go over the neck of the valve to hold it. Then used my hands in a karate kid fashion. Does that make sense?

This is my set up ... I don't see where a spring would go :/

[This message has been edited by Notorio (edited 04-02-2019).]

quote Originally posted by Notorio: I don't see where a spring would go.

Between the underside of the valve and the head. Otherwise, the full weight of the valve is pressing on the seat... and your suction cup slips off because there's too much friction.

Battery drill with "keyless" chuck. With the head standing on one end. Put a piece of straw (or valve seal protector)over the end of the valve sticking through the head. Hand tighten the chuck onto the valve stem. Just enough to grab the valve, but not to bite into it.. Leaving a little room for the valve to be a little open. Use the drill to "spin" the valve.

I don't know if the diameter of the dish in the valve face is somehow interacting with the perimeter of the suction cup.

Anyway, you could try hot melt glue; I often use hot melt glue for temporary mockup type things. When you're done, hot melt glue easily peels off with the application of isopropyl alcohol as it seeps in between the hot melt and the component.

Are your hands high up on the wood stick? This is to avoid placing a side load at the bottom which could cause the suction cup to unstick.

[This message has been edited by pmbrunelle (edited 04-02-2019).]

quote Originally posted by cmechmann: Put a piece of straw (or valve seal protector) over the end of the valve sticking through the head. Hand tighten the chuck onto the valve stem. Just enough to grab the valve, but not to bite into it.. Leaving a little room for the valve to be a little open. Use the drill to "spin" the valve.

Let's see you try that method with a flathead.

quote Originally posted by Patrick: Between the underside of the valve and the head. Otherwise, the full weight of the valve is pressing on the seat... and your suction cup slips off because there's too much friction.

Ah hah, I get it now!! There is no such spring in my hardware drawer but will look for something at Home Depot or fashion something homemade.

As far as where I am holding my hands, they probably ARE closer to the valve end than higher up the tool so I will try to break that bad habit.

As far as hot glue goes, not a bad idea that. Shall try that if the top two remedies still leave me scrambling. I forgot to mention that I DID already try running a glue stick over the suction cup before attaching and sometimes that helped a lot but mostly just made it worse. Perhaps the glue was not semi-dry and sticky yet in those cases where the tool came right off.

As far as the drill chuck method I wanted to do it manually so I could easily 'hear' the change of sound the abrasive makes when it is broken down and needs to be refreshed. Plus I was afraid that with my luck I would bias to one side and create a problem for myself later.

This is what I was talking about.



That is how I did mine after trying to use that suction cup tool. Using a drill is entirely up to you. I did it by hand mostly but my valves were pretty bad and I just got tired. Hindsight I should probably have gotten new ones but oh well. I have about 400 miles on the rebuild and no problems so far.

quote Originally posted by Spadesluck: I did it by hand mostly but my valves were pretty bad and I just got tired.

IMO, valve lapping is done just to ensure good contact around the entire circumference of the valves and the seats. If the valves and/or seats are badly worn, pitted and/or burned, they probably need to be re-ground (or replaced).

[This message has been edited by Patrick (edited 04-03-2019).]