What is my next step with the valves?

[old31]

What should I do next?

Do the white areas on the valve tips on #2 cylinder mean anything? Is it of concern? All the other valves on cylinders 1,3 and 4 are all brown.

#2 on a compression check reads 40 lbs less than all the other cylinder's.

On a leak down test all cylinders are good except#2. I could hear a leak out the exhaust.

[alexiskai]

One possibility: worn guide on the exhaust valve. Could lead to oil from the valve chamber getting past the guide and being deposited on the seat, causing a bad seal, as well as being deposited and burning on the exhaust side of the intake valve, causing that white color on the side facing the exhaust.

I would crank the engine around and inspect the valves as they lift.

[Bob C]

Do you have big intake valves or is it just the camera angle??

[Richard Knight]

Make sure there is clearance on the valve adjustment. If so remove ex valve and look at valve seat and valve face.

[nkaminar]

Remove valves. Keep track of which valves go in which holes by drilling 8 holes in a stick and putting the valves in the stick in order. Label the holes with a marker. Clean with wire brush but don't scratch stems. Check for looseness in guides. Put you finger on the bottom of the guide and pull out the valve. It should make a pop sound as it is pulled out. (Doesn't work with two part guides.) If valves are loose in guides, measure stems and replace valves if beyond spec. Replace guides if necessary. If valves are pitted, burned, or the surface is very concave, grind the valves and re cut the seats in the block. If the valves are too bad, replace them. If the seats in the block are too bad have hardened seats installed. If in fairly good condition, lap valves using a lapping compound. Remove all traces of the lapping compound and re assemble. Measure spring force or replace springs. Replace all springs that are weak. Replace all damaged keepers. If you don't have them, consider modern valves. Make sure the valve clearance is correct. Use assembly lube on the stems when replacing the valves. Report back to the Barn when you have the engine running again.

[old31]

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Originally Posted by Bob C

Do you have big intake valves or is it just the camera angle??

The intakes have been enlarged, good eye.

[Flathead]

The white is from being super hot and burning in that area. Need a valve job.

[old31]

So what do you guys recommend for lapping compound and tools to dress the valves?

Or if the white is from being burnt, do you recommend I replace the valves?

Do all valves, or just the problem number two cylinder?

[alexiskai]

Originally Posted by old31

So what do you guys recommend for lapping compound and tools to dress the valves?

Or if the white is from being burnt, do you recommend I replace the valves?

Do all valves, or just the problem number two cylinder?

There's two meanings of "burn" going on here. There's burn in the sense of combustion byproducts and oil being deposited on the valve and oxidizing. Then there's burn in the sense of a "burnt valve." Burnt valves are valves that have been physically damaged by prolonged excessive heat. They are cracked or misshapen.

You don't want to do more repairs than are necessary. The next step is still to closely inspect the valve, guide, spring, lash, and seat for both valves in #2. Figure out where that exhaust leak was coming from. Find out whether all components are up to spec.

[nkaminar]

While you are at it, do all the valves.

Lapping compound here: https://www.amazon.com/Permatex-8003.../dp/B000HBM80M

Tool here: https://www.snydersantiqueauto.com/p...1272&cat=41910

Took also available on Amazon

[nkaminar]

Take the valves out and wire brush (rotary powered wire bush). Any severe damage will be obvious.

[old31]

Yikes, I just checked for Valve spring testers, they don't give those things away. Nothing used on ebay.

I have ordered the compound and tool and will take out all the valves.

Are these of any value?

https://www.ebay.com/itm/38512401335...Condition=1000

[Patrick L.]

You say you hear the leak from the exhaust and have not mentioned the clearance on any of the valves.
A small leak like that from a valve means it's just starting to 'burn' or has too little clearance.

[old31]

Both intake and exhaust are adjusted to .014.

[johnneilson]

These pressure test units do work well enough for the mod A valve springs

The pressure spec is pretty low for stock and if a guide is just slightly tight can cause valve leaking with resulting damage

I know many on this site recommend the Les Andrews books but I would suggest Jim Brierley’s more

The only way to know what the problem is to disassemble
Forensic diagnoses can only be done this way and need to pay attention to concentricity of valves to seats

John

[nkaminar]

A bathroom scale can be used to check the springs. Cut a wood block to the recommended height to put next to the spring. Now push down on the spring until the top is level with the block and look at the reading on the scale. You can rig a lever using some 2X4's and a door hinge to help to push down. A 2X4 can be cut to the right height so that the lever is horizontal when the spring is at the right height. The door hinge is screwed to the standing part and the lever. Attach the standing 2X4 on a piece of plywood that the scale can rest on.

[katy]

Originally Posted by old31

Yikes, I just checked for Valve spring testers, they don't give those things away. Nothing used on ebay.

Just use a spring bathroom scale on the drill press.

The test pressure of a Model A valve spring is about 50 lbs at 2.340 inches

[Jim Brierley]

With 40 lbs. difference on a compression test lapping the valves will not accomplish what is needed. You will need to have both the seats and valves ground on a machine, you will probably need at least one new valve. Do it soon to prevent cracking the block.

[old31]

Katy, thanks thats good info, I will do it that way.

Jim, At this stage I will go as far as I can with out having to pull the engine (again).

[Patrick L.]

The valve lash seems too small for me.
How does the valve face/seat look ?
I'm not a fan of lapping, so, I too think the valve and seat need to be cut. If you can find access to the equipment it can be done without removing the engine.