Engine seems to start but rolls to a stop

[GrowleyMonster]

Originally Posted by JustinT

Thanks for the info Growley.
Here is a video of the moving exhast valve: https://youtube.com/shorts/R8PwwUk9I...6Zzw8YmlJvXwVU

Usual procedure when replacing a valve is to at least lap it. Get some valve grinding compound and put a little bit on the mating surfaces of valve and seat. stick the valve in its seat. Try not to get any on the stem or in the valve guide, if you can help it. A little dab will do ya. Chuck it into your electric hand drill. If it isn't long enough then use a piece of fuel hose and hose clamps and a miscelaneous drill bit the approximate size of the hose as an extension. Pull upward lightly as the drill turns and the abrasive compound will make the valve and seat conform to each other good enough for a decent seal. There are various ways to simply check for a seal, too. A leaky valve will rob your engine of compression and power, and possibly erode the valve guide and rod. So make sure you have valves that do their job before wasting an expensive head gasket putting it back together prematurely.

When you are done lapping, make sure you clean up all residue. Obviously you don't want abrasives in your engine when it is running.

You can probably find some good vids on youtube on lapping valves.

No drill? You can do it by hand, just spinning it manually, if you are patient.

You can also do it from the cylinder side, with a wooden dowel chucked into your drill. Touch it to the valve and let the friction of dowel to valve spin it. You might use a bit of chewing gum or a piece of inner tube rubber to give the dowel more grip.

[JustinT]

Thanks all.
I'll remove the pipe and have a closer look.
Discovered the other rocker arms are quite stiff, perhaps the pipe wasn't oiling them.

I'll do said lapping, thanks

[JustinT]

Originally Posted by GrowleyMonster

Usual procedure when replacing a valve is to at least lap it. Get some valve grinding compound and put a little bit on the mating surfaces of valve and seat.

I'm ordering some, should I use coarse or fine grades? I assume fine.

[GrowleyMonster]

Originally Posted by JustinT

I'm ordering some, should I use coarse or fine grades? I assume fine.

Whatever blows your skirt up. Coarser grades cut faster. Finer grades leave a nicer surface and better seal. Ideally one chooses the grade that gets the bulk of the heavy lifting done quickly, then cleans up and goes finer to finish the job.

You can check your progress by wiping away the compound and painting the mating surfaces with DyKem or similar machinist's dye, or even paint it with a Sharpie marker, give the valve a quick spin, and then see where the dye or ink remains and where it was worn away immediately. This shows you where you have good contact and where you still need some work. If you block the manifold you can attempt to pressurize it with the valves held in the closed position and see how much, if any, leakage you have. Later, after you have the head torqued down, you can repeat your compression test, but an unsatisfactory reading then, will have you pulling the head again. What you want is to ensure, with as much certainty as possible, that the more or less mandatory post-repair compression testing will give you a decent reading, conforming to the specs given in your manual. The actual reading will just be confirmation that you didn't drop the ball and overlook something.

[JustinT]

I see, exelent advice, thank you. The search for good compression is certainly worthwhile, fed up with the engine being substandard and this is all worthwhile for sure.

[jamhass]

Back in the day we used one of these to lap valves:

https://www.amazon.com/Thsakzo-Lappi...742db1249a64ea

[JustinT]

Originally Posted by jamhass

Back in the day we used one of these to lap valves:

https://www.amazon.com/Thsakzo-Lappi...742db1249a64ea

The valve grinding compound I ordered comes with one of those.

[JustinT]

Originally Posted by GrowleyMonster

That sounds logical, Pete.

Justin, can you blow air through it? And does it seem to not be cracked?

I discovered that two rockers were very stiff, in-fact, they are the exhaust on the un-stuck side and the inlet valve on the stuck side were basically hinging on the rocker shaft in unison. The inlet valve rocker on the good side was actually the only free moving one, and even that was minimal. Now they are all lose and very free moving. All quite blocked up. I assume no oil was getting to them for a long time, and even when it could, the channel was blocked. Now to pay attention to that rocker arm oil pipe.

[JustinT]

Getting there.
I have lapped my valves now.
Two rocker arms were seized but they are now free moving, so 4 free rocker arms now.
I think they were starved from oil as the rocker arm oil feed pipe had been squashed by the push rod when the valve seized up (clearly it as happened before!)
Been unable to open up the copper pipe of the oil feed so I may get a engine shop to do that for me, can't find the part online anywhere.
Don't want the rocker arms to seize up again!

[jamhass]

Carefully check and clean the INSIDE of the rocker shaft. It has an internal oil passage that can get plugged up, especially if oil supply is compromised.

[JustinT]

Originally Posted by jamhass

Carefully check and clean the INSIDE of the rocker shaft. It has an internal oil passage that can get plugged up, especially if oil supply is compromised.

Thanks, yeah, the whole shaft was pretty plugged up.

[JustinT]

Picture of a flat pipe!

[skipperpete]

That ain’t good, and yes…..you will be replacing that pipe.

[jamhass]

Interesting photo. The nut looks like It might be a compression fitting. If so, at least that end is easily DIY. What's the other end?

[JustinT]

There is gauze on the holes under the head, do I need to replace that? I can't find anything in the manual about it.