T head engine by Brian

[Toolguy]

Going from .026 to .049 is a big jump in spring pressure. I bet the new springs will seal the valves, but may put a lot of wear on the cams. Time will tell.

[brian Rupnow]

Toolguy--that is why I made the cams and lifters from 01 steel and hardened them. You could pound on them all day and not hurt them.

[chipmaker4130]

Toolguy--that is why I made the cams and lifters from 01 steel and hardened them. You could pound on them all day and not hurt them.

Two parts of the same hardness will still wear. The wear is minimized if both are polished and if they are lubricated.

[brian Rupnow]

Yes, they will wear. They won't "wear out"--Not in my lifetime anyways. It is a model, not a 24 hour a day powerplant.

[Toolguy]

I didn't realize they were hardened tool steel. They'll be fine. I will have to read more carefully next time.

[brian Rupnow]

The Helicoils worked great. I have never used them before and I must say, they work fine and don't require a lot of work to use them. I did machine new spring cups and install them and the heavy valve springs on the engine, but it didn't really help. I then took the cylinder head off the machine and ran a 0.200" diameter drill up from the bottom side of the valve cages, about 0.6" to cut down on the amount of friction between the valve stems and the valve guide portion of the valve cage. I took the heavy springs and cups off and put the originals back on. I reground the valves. Nothing really helped get my compression back. Something I have noticed over the years--When the seat portion of the valve cage gets too large, it is almost impossible to get a good valve seal. I'm stumped at the moment. I may machine new valve cages and reface the valves in the lathe, more or less starting over again with the valve sealing issue. I have rechecked the valve and ignition timing, but they are fine.

[chipmaker4130]

Brian, how do you maintain alignment (square and concentric) of the valve seat with the valve guide? In a commercial setting valve seats are ground after insertion or repair of the valve guide and it is done using a mandrel in the valve guide for alignment/concentricity.

[Sparky_NY]

The Helicoils worked great. I have never used them before and I must say, they work fine and don't require a lot of work to use them. I did machine new spring cups and install them and the heavy valve springs on the engine, but it didn't really help. I then took the cylinder head off the machine and ran a 0.200" diameter drill up from the bottom side of the valve cages, about 0.6" to cut down on the amount of friction between the valve stems and the valve guide portion of the valve cage. I took the heavy springs and cups off and put the originals back on. I reground the valves. Nothing really helped get my compression back. Something I have noticed over the years--When the seat portion of the valve cage gets too large, it is almost impossible to get a good valve seal. I'm stumped at the moment. I may machine new valve cages and reface the valves in the lathe, more or less starting over again with the valve sealing issue. I have rechecked the valve and ignition timing, but they are fine.

Have you redone your test with the air hose in the spark plug hole? That would help verify it is indeed a valve sealing issue before starting to remake parts. Doing the test again "wet" to verify ring leakage would be assumed.

[brian Rupnow]

Chipmaker--The valve cage is a one piece unit that has the valve guide and the valve seat all carved from the same piece of material, brass. It is finished everywhere except the valve seat. Then it is lightly pressed/mostly Loctited into the cylinder head. Then a special guided tool is inserted into the valve guide portion and turned by hand to cut the valve seat. The valve is machined to size, then inserted into the valve cage after the Loctite has dried. Then some 600 grit grinding paste is applied to the seating area of the valve and the valve is rotated by hand against the valve seat to make an airtight seal.---and about 75% of the time it does just that. 25% of the time, you won't get a good seal, and it will drive you crazy trying to figure out why.

[brian Rupnow]

Sparky---Today I tried everything I knew about, and half a dozen things that I didn't.---I'm going out to the garden now and eat worms!!!

[Sparky_NY]

Sparky---Today I tried everything I knew about, and half a dozen things that I didn't.---I'm going out to the garden now and eat worms!!!

So, you confirmed the valves leaking by testing?

[Ringo]

earlier you mentioned that if the valve seat area is too wide it becomes difficult to seal.
Have you tried a 3-angle valve job?

[rdfeil]

Sparky---Today I tried everything I knew about, and half a dozen things that I didn't.---I'm going out to the garden now and eat worms!!!

Brian,
I suggest using the worms for fish bait and eating the fish. It is relaxing and allows you to think easily AND provides a tasty dinner!!! You will figure it out as you always do 🐟

[chipmaker4130]

Chipmaker--The valve cage is a one piece unit that has the valve guide and the valve seat all carved from the same piece of material. . .

That sounds like a good process, shouldn't be any issues with alignment then as long as you do it all in one chucking.

[brian Rupnow]

Ringo--We're talking about a valve that is 3/8" diameter at the head. I think a 3 angle grind is two angles beyond what I can do.