Tedious work...

[SilentUnicorn]

lappin valves...




m

 

[DrEntropy]

Not to mention the bruises on the hands if ya do it with a "swizzle stick".

 

[aeronca65t]

And you probably know this, but not all folks do this anymore.
I don't.
I just use some bluing to see if the valve face is hitting in the center of the seat (after cutting the valves and seats). I cut all my valves three-angle.

I know people who swear by the idea of lapping and others who think it's a waste of time.
I realize the older BMC manuals recommend it and I doubt it really hurts anything.

 

[SilentUnicorn]

I know some people say it is not needed.

i cant hurt, might help..time is cheap, its not even the 1st of march, i have time.


"swizzle stick" (haven't heard that term in a while)is what i am using.



m

 

[Banjo]

If ya got the wooden stick with the suction cups on the ends, then yes.
I've also been known to put the valve in the head, stick a piece of hose over the valve stem, the other end over a drill bit roughly the same size as the valve stem in a low speed drill, and save my hands.

 

[GregW]

I look at it as practice if I ever need to start a fire in the wilderness.

 

[DrEntropy]

:lol:

I have a number of the wood handled vatiety and one tool with a hand crank. It does a reciprocating "dance" and I just pull it up now-and-again to re-wet the seat. The drill method only goes one way, I don't (gut reaction, only MY opinion!) like the idea.

Always a three angle cut, narrow seat. Whether or not it's 'necessary' it's the way I've usually done it. Most of my personal street engines have gone for years even with my heavy boot. The ones done for clients didn't boomerang either so it's been part of my practice for years.

 

[Bayless]

The drill method doesn't sound too good and three angles sure seems to give a better and longer lasting seal. I have one of the hand crank tools too. Really handy although I doubt you could ever start a fire with it.

 

[SilentUnicorn]

The drill method...

I have been trying to understand why this might not be good. Going both ways with the swizzle stick is how i was taught. Never questioned it. Thinking about it the reversal of the action most likely helps the grit do its job. Is there another reason?

It would seem that you could reverse the drill and get the same effect. If used as Banjo said - on low speed what are the dangers?



m

 

[DrEntropy]

Concentric "rings" as opposed to even "irregularity" of the contact surface would be my first WAG. The lapping process is just preparing a full contact surface for seating. Like hand lapping a shim or other flat widget, a "figure eight" motion while lapping produces a more even, parallel-to-plane finish than going in circles.


As I said: that's just my first WAG.

 

[Banjo]

I'd never been called on that method. I do tend to switch the drill forward and reverse while doing it that way. But if it's not a good idea, I shall henceforth abstain from such practices. hehehehe
I've never use it on a 3 angle job before. It was always on a tired engine that was just getting the valves re-lapped.(cheapskates)

 

[DrEntropy]

I'm sure I ain't th' "last word" on valve lapping, Benny. Whatever works is good. You're in a "production environment" and with "cheapskates" as you say, there's no sense using up clock to NOT satisfy 'em in the end anyway... IYSWIM. :wink:

 

[GeeBee1]

I'd never been called on that method. I do tend to switch the drill forward and reverse while doing it that way. But if it's not a good idea, I shall henceforth abstain from such practices. hehehehe
I've never use it on a 3 angle job before. It was always on a tired engine that was just getting the valves re-lapped.(cheapskates)

Ben:

I have used it for a quick and dirty job as well, with no prob's.

I would not use it on a three angler nor ever have.

Its like decompressing the valves with a combo wrench and a socket and a friend, with just enuff money for the meisters and the kero to keep the feet from freezin days.

Pat