Valve Lapping

[oldskydog]

OK, its not a 409 but it has 470 cubic inches with a 5 inch bore and a 4 inch stroke so maybe it will be of general interest.
I'm doing my annual airworthiness inspection on mu 46 Navion and while doing the leakdown check found #4 cylinder hissing out the intake and only able to hold about 30 psi out of 80 at TDC. Video scoped the cylinder and found a good bit of lead deposits on the outboard edge of the valve and seat while the inboard side showed some heat staining from standing up next to the exhaust valve. No burn damage noted but stem was coked up some from lead as well. Not being able to get exited about pulling the cylinder, I decided to try lapping the valve in place. Put it on TDC and stuffed a length of nylon rope in the top spark plug hole until it backed up the intake valve then removed the rocker arm, put the spring compressor on and pulled the springs. Pulled the rope out and backed off the piston from the valve about an inch and pushed the valve in to where I could get a pipe cleaner with some lapping compound on the face, connected some vinyl tubing over the stem head and safety wired it in the keeper groove then started spinning away. After a while It felt pretty smooth and appeared to be seated thru the scope so I cleaned it up, put the upper plug in and the compression guage air on the bottom and gave it 80 psi on TDC and it came up to 65+ but still a little hissing from the intake so more work is needed. I'll do some more lapping tomorrow. Meanwhile DI tested the springs and they are way below spec at installed height but still close to spec on open pressure. Have a new set of springs on order.
Did I mention I hate pulling cylinders?

 

[oldskydog]

 

[1964SuperStocker]

Being a pilot myself I know your frustration. We have to be so careful and so vigilant that it can take the fun out of flying. Just remember that on take off you want to know your baby is ready to go on the roll out. All of this work will ensure you are safe, your passengers are safe and the losers stuck on the ground are safe. Plus your N speeds will be consistently met with the power you need on hand to keep your bird flying.

 

[Fathead Racing]

Why wouldn't they put valve rotators on these engines?

 

[oldskydog]

They do but on exhaust only. The exhaust valves are usually the problem.

 

[La Hot Rods]

I remember cleaning the lead deposits off the plugs out the Piper fleet at Woods Memorial.

 

[Blk61409]

Cecil, that is insane!!

Congratulation!!!! Not on getting the cylinder rebuilt, but actually flying it again!

As us guys just have to hope ours cars will stop, yours is a bit more challenging!!

 

[Phil Reed]

Cecil....thought you sold the Navion???

 

[oldskydog]

Nope, sold the T-28.

 

[plumcrazy]

Hey Cecil!

I hate to ask this "out loud" but if you could set up a camera and fil what your doing, i'd LOVE to see how your doing it! Its a technique Ive never seen and love to learn. If not, no sweat, just figured i'd ask.

 

[Don Jacks]

And to think that just last week we[some of us] were talking about "Flat-Raters" who cut a hole in the grille to speed up cam changes .This takes that term to another level ,not that I wouldn't have tried to do the same thing.

 

[WARPT]

WOW! Impressive!

 

[oldskydog]

Hey Cecil!

I hate to ask this "out loud" but if you could set up a camera and fil what your doing, i'd LOVE to see how your doing it! Its a technique Ive never seen and love to learn. If not, no sweat, just figured i'd ask.

No magic here. You just have to get to the valve face to get some compound on it. To compress the springs you have get something solid behind them so that's what the rope does. You have to keep the valve from dropping into the cylinder so at top dead center the valve bottoms on the top of the piston and can't drop in. I used vinyl tubing over the valve stem to grip it for turning by hand. You could also use a drill.
The hard part is cleaning the compound off the valve and seat.

 

[DonSSDD]

Cecil, that is insane!!

Congratulation!!!! Not on getting the cylinder rebuilt, but actually flying it again!

As us guys just have to hope ours cars will stop, yours is a bit more challenging!!

Airplanes always stop, one way or another.
The hands on knowledge on this site for so many things is remarkable. One thing needed is to pass this on to the next generation.

Was talking to a guy yesterday , he has a dually 1927 International, it has that spark advance on the steering wheel and he has no idea how it works. We discussed how these sorts of mechanical devices are why model a’s etc stopped being in demand, no one knows how to fix them. I said the lack of knowledge in the younger generation for carburetors will lead to a lack of demand for vehicles without fuel injection.

May have to replace the W with an LS or an electric motor?

 

[Don Jacks]

Convert the W to EFI.In some cases,it's cheaper than a "correct" carb.

 

[Iowa 409 Guy]

Airplanes always stop, one way or another.
The hands on knowledge on this site for so many things is remarkable. One thing needed is to pass this on to the next generation.

Was talking to a guy yesterday , he has a dually 1927 International, it has that spark advance on the steering wheel and he has no idea how it works. We discussed how these sorts of mechanical devices are why model a’s etc stopped being in demand, no one knows how to fix them. I said the lack of knowledge in the younger generation for carburetors will lead to a lack of demand for vehicles without fuel injection.

May have to replace the W with an LS or an electric motor?

It doesn't take a guy long to figure out what the spark advance does on my Knuck....

 

[plumcrazy]

No magic here. You just have to get to the valve face to get some compound on it. To compress the springs you have get something solid behind them so that's what the rope does. You have to keep the valve from dropping into the cylinder so at top dead center the valve bottoms on the top of the piston and can't drop in. I used vinyl tubing over the valve stem to grip it for turning by hand. You could also use a drill.
The hard part is cleaning the compound off the valve and seat.

So smart and thanks for sharing, such a slick and great tech tip!!..... I would have never known to do this and wasted time and money pulling the head and still being in a pickle. Soaking, tearing down, this is really smart!! Maybe we need a tech tip section?

I love seeing the guys on Gold Rush Macgyver all kids of things back together. A couple weeks back someone had a hole in a radiator and put in a dozen eggs and walla, able to run for another day. Another show, a fella broke a huge pin for a dozer arm. Pin must have been 2 ft by 6 inches thick, ,broke in half. All precision machined. They ground down the center on both pins, kinda like the shape of a pen tip. Put them both end to end facing each other and filled it with welding rod till it was flush with the top, sanded it and walla, back in and on the way...