Removing valve springs in-situ

[ardiesse]

I think my Humpy may have sticking exhaust valves.

I Googled "un-sticking valves" and emerged in the world of light aircraft engines.  I didn't know that you could (legally) work on your own aircraft engine.  Turns out that using various special tools, you can release the valve spring collets and remove the valve spring.  Then, having removed the exhaust manifold and working through the exhaust port, you push the valve through into the cylinder, being careful to grab onto the valve stem with a grippy tool so you don't lose the valve inside the cylinder.  After that, it's a relatively straightforward operation to send a greased reamer down the exhaust valve guide to clean it up.  Starting the exhaust valve back into the guide takes some dexterity, and then when that's done, you reassemble the engine and take the aircraft for a test flight.

Yeesh.  But I got to thinking.  You can remove the valve springs from red motors using Tool 6A38, which is basically a big, bent fork.  Can this technique be adapted to grey motors?  I imagine you'd remove the adjuster stud and nut from the rocker, slide the rocker along the shaft, remove the pushrod and then engage the magic tool, while pressurising the cylinder with air.  The magic tool would be in the form of a cranked lever with a two-pronged or ring-shaped end . . . wait a minute . . . that sounds very much like a ring spanner.  To test the concept, I need

- Assembly, cylinder head, 1
- Shaft, valve rocker, 1
- Pedestal, rocker shaft, 2
- 5/16" UNC bolts, various
- spanner, ring, cheap crappy, 3/4" - 7/8", 1

An old el-cheapo 19 mm ring spanner very nearly fitted.  I needed to grind away some of the webbing to make it sit close to centre over the valve spring cap, and then "enthinnen" the end of the ring so the valve spring cap isn't crooked when the valve spring's compressed.



Here's the spanner in place.  It's not too hard to remove the collets with long-nose pliers.  Getting the valve stem oil seal out was more of a challenge, but my Humpy pre-dates valve stem oil seals.



Valve spring and cap removed.



Next:  slip a length of PVC tube over the valve guide and fill it with kerosene or Redex or similar.



My hunch is that there's gunk adhering to the valve stem, which jams into the end of the valve guide when the valve's shut and prevents the valve from seating properly.  I believe the test for this is to rotate the valve stem when the valve's closed.  It should spin freely.  I'm hoping that a couple of days of solvent running down the valve stem should soften the gunk up enough that I can free the valve with a drill.

The back-up plan, of course, is to pull the head off, decoke and grind the valves, along with checking the exhaust valve stem-to-guide clearances.  That risks turning into a rebore though.

(Thanks to Brett for the donor cylinder head)

Rob

[ardiesse]

Today I tried the method out in earnest. I used a Ryco compression tester adapter and a Ryco-style fitting on the air hose. But, as always, it was a little more complicated than anticipated -

- I couldn't slide the rocker along the shaft far enough to completely clear the valve spring cap
- I couldn't squeeze the ring spanner between the rocker and the valve spring.

I ended up pulling the rocker gear off. I decided to attempt no. 2 first, turned the motor to TDC on no. 2, put the car in top gear, bolted in the dummy rocker shaft, pressurized no.2 cylinder, worked the ring spanner into place, and took the exhaust valve spring off. You beauty.



The valve opened under its own weight, and when I spun it by the stem, closed, the valve spun freely. No. 2 exhaust valve's not sticking. I reassembled the spring.

Same deal with no.3 exhaust valve. It's not sticking. No. 4 was the same, but I can tell I was getting tired: putting the collets back took ages.

Number 5 exhaust valve didn't spin freely when closed, and took a bit of a push to get it off the seat. So I've put PVC tube over the guide and sprayed WD-40 into the tube. I'll let it sit overnight, then chuck the valve stem into a drill and attempt to free the valve up.

Don't know what to do with numbers 1 and 6. They've always been the high-reading cylinders when I compression-test the motor. I'm inclined to let them be.

Rob

[ardiesse]

Letting WD-40 run down the valve guide overnight has yielded results - no.5 exhaust valve now spins freely when closed.  I'll take mother out for lunch, then chuck the valve in a drill and give it a good whirl.

Rob

[ardiesse]

I freed up no.5 exhaust valve and gave it a "rough-as-guts" abrasive-free valve grind with a drill:  Initially I set the air pressure to about 10 psi, but with the weight of the drill on the valve, it didn't stay shut.  So I upped the air pressure to about 20 psi, which allowed the valve to stay shut with the extra weight of the drill.  Then I squeezed the trigger and spun the valve gently.  After a few seconds of that work, the valve then stayed firmly shut with the drill weighing the valve down.  I could hear the blow-by into the crankcase, but couldn't hear anything out the exhaust.  Good sign.  More WD-40 on the valve stem, opened and shut the valve a few times, and a minute or so with the drill.  I un-chucked the drill, disconnected the hose, and spun the valve with my fingers.  It felt smooth to spin on the seat, so I figure the drill did some good.

Meanwhile, the Greystanes Special Tool Company came good with a Lisle valve spring compressor.  I gave it a practice-run on Brett's donor cylinder head.  The tool needed adjustments to get right, including one gotcha:  if you attempt to hold on too far down the valve spring, the compressor's claws bind between the spring coils on assembly of the valve cap and collets.  But it's much easier to re-install the spring using the tool: you have two hands to get the collets in place.



I put the rockers back on and checked the valve clearances in the most basic way possible: Can I spin the pushrods when each cylinder's at the firing instant?

And I turned my attention to the ignition system.  The marks on the electrodes of the distributor cap suggested that the cap and rotor are misaligned.  This seems odd.  And then I remembered something about Bosch FJs having different caps and rotors from the later models.  As a result-

The Idiots' Guide to Bosch Distributor Rotors



FJ distributor rotors are maybe 3 mm shorter than the later models' rotors.
Red motor Bosch distributor rotors have a similar body to the FE-EJ distributor rotors, but the electrode is much longer.  Which leads to this insight:  With care, you can shorten a red motor distributor rotor to suit a grey distributor.  In emergencies, that is.

I had been running the car for what - six years, nine years, with an FJ distributor rotor.  I went through my stash of old ignition parts and found a serviceable FE-EJ distributor rotor.

And then I took the car for a test drive.  It's much improved.  The idle's way smoother and the motor just feels more tractable.  How much of the improvement's ignition-related?  Most, maybe.  But unsticking no.5 exhaust valve will have done no harm at all.

SA All-Holden Day, here I come (fingers crossed).

Rob

[Errol62]

We will put you in the corner with the other Humpys Rob, next to Stewy and the SA club. Look forward to seeing the car and you, and offloading those parts.


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[ardiesse]

Today I went for a test drive up to a friend's on the Central Coast.  The official reason was to deliver a replacement valve, that is, a thermionic valve, for the reverb unit in his vintage Hammond organ.

The car went well, but it coughed and fluffed a couple of times.  And on the way back, the idle "sagged" to the point where it nearly died at traffic lights.  It's almost like fuel starvation . . .

Got back home and had a look at the fuel pump with the engine idling.  The fuel in the bowl was down to the level of the inlet, way below the gauze filter, and when the fuel flowed into the pump, air bubbles came too.  So I've either got a leaky hose or pipe union, or the fuel pipe's blocked.  I pulled the inlet hose off and gave it the "suck test": it held vacuum, and when flexed too.  I put the hose back on the pipe and led the fuel pump end into a jar, did my best Dizzy Gillespie impersonation at the fuel filler, and found that I could fill the jar with fuel, which then siphoned back into the tank.

Thus far I've found nothing wrong.  I put everything back together and started the engine.  The fuel in the glass bowl rose to the level of the gauze filter, and no air bubbles came out of the inlet.  Don't know what I did, but it worked . . .

Rob

[ardiesse]

. . . it worked, because I hadn't put the fuel cap back on when I started the engine.  Today, after driving the car, I noticed the same symptoms . . .

and checked the fuel cap.  It had no vent.  I put it in the naughty corner, got out my old, dinged original equipment cap.  Problem gone.

It's a lot of little, subtle things whose effects add together: sticky exhaust valve, wrong distributor rotor, wrong fuel cap.

Rob

[ardiesse]

I'm not out of the woods yet.

This morning was a glorious opportunity to head up to Mount White and take the old two-lane road back, so I did. The car was very happy, except waiting to turn right off the Pacific Highway near home, when the idle "sagged" again. With the engine idling at home, there were lots of bubbles coming out of the fuel pump inlet, and when the fuel level in the pump bowl rose to the gauze, the idle came good.

The tank was less than 1/4 full. I'm beginning to think there's a crack or pinhole in the fuel riser pipe inside the tank. To double-check, I'll take the stationary engine tank from the test stand and plumb it into the car's fuel pump. If no bubbles, I'll fill up the car, and park it on a slope, driver's side downhill. The fuel riser pipe should be immersed in fuel for its whole length. If I don't get any bubbles in the pump bowl, that'll be a confirmed diagnosis.

My 1957 master parts catalogue lists the fuel riser pipe as a spare part, so they were a serviceable item. But at this point, I'll need to find someone who can repair fuel tanks.

Rob

[my8thholden]

Rob ...repair of metal fuel tanks is almost a lost art ,there was a bloke in Parramatta but I believe he has retired , most plastic tanks are " put a new one in "...there is a bloke associated with the Velocette motor cycle club who does bike tanks ,he may help or know who can, I think I can get his details for you , gimme few days ... Vern ..

[ardiesse]

Vern,

I'm not so sure about the leaky fuel riser pipe hypothesis.  I was about to try the hose-in-jerry-can trick and saw that the fuel pump bowl was full to the top.  That wouldn't happen if the fuel riser was leaking.  I started the car and ran it for about ten minutes.  There was no hint of air bubbles at the pump inlet, and the engine ran sweetly.

Since the apparent air leak happens when the engine's hot, I'll have to try the hose and jerry can when the engine's hot and the fuel system's misbehaving.

Rob