Valves

Finally found some motivation to drive to that winter cold garage of mine for a short mechanical investigation on that second hand engine I bought. With the inlet and exhaust valves almost touching each other, I was curious about the exact measurements. The inlet is 41.3mm thus being exactly what I have in my engine now and the second biggest.
Available at Burton at the time being:
38.15mm
39.3mm
40.6mm
41.3mm
42.7mm
The exhaust valve is 34.9mm compared to 34.0mm actually in my engine.
Available at Burton at the time being:
31.6mm
34.5mm
34.9mm
36.0mm
36.2mm
So really nothing spectacular to report here. At first sight, the remaining flange between the valves looks quite narrow, but it is always best to unmount the parts when measuring. There is still some possible improvement when preparing the cylinder head of the replacement engine.
Cheers.

Cleaning the valves

The cylinder head and one of the valves are at ANG for a new lease of life. Their verdict was quite ok, so I left everything there for them to do some work on the valve gear:
- the crack is not critical, there is enough space around for the gasket to keep it sealed
- the seats are not for lead-free and don't have a three-angle cut
- the copper insert that came out is a K-Liner and they don't like them at ANG (neither do I)
I decided to go for new guides instead of fumbling around with K-Liners, and new seats. Today I cleaned all the valves, springs, retainers and cotters to bring them to their workshop on Monday.
Cheers.

Headwork

The cylinderhead showed some leakage around the valves when I tested it with petrol. One good reason to take the valves out and regrind them. Tonight's job: disassemble the cylinderhead. Say hello to my new tool, the valve spring compressor.

This tool permits to compress the valve spring. Then you get access to the cotters and can take them out. Release the spring and the valve spring retainer comes off. The valves come out, some by themselves, some need a little persuasion.

The valves should not mix up, cardboard helps to keep them sorted. Unfortunately, one copper insert came out with its valve. Tapping it back in didn't work.

This leaves me with two more problems: #1 getting an insert off the right size and #2 find the right valve stem seals. Those in the seal kit (left) aren't the same as in my engine.

And one more to prepare a sleepless night, how about this little crack? Is this serious? I will further investigate with some specialist friends and decide what to do.

Cheers.

Petrol leak test

The compressed air test was not very concluant. That's why I took off the head yesterday. Other tests can now be done like the petrol leakage test. It consists in pouring some petrol on the top of the pistons. A faulty ringset will not keep the petrol on top as long as the others. With the pistons at the same height and a stopwatch, you can see what happens and how fast.

Cylinder #3 leaked well ahead of the other three. The pic shows it dry when 2 and 4 were still wet.

The same test can be repeated with the cylinder head by filling the exhaust duct (valves slightly leaking, but not a lot)...

... and the inlet duct (valves completely dry).
A Caterham owner and X/flow expert will tell me what to do next. I guess it means dismantling the bottom end, as already written in an earlier post.
Cheers.

Head off

Start of dismantling. Both manifolds off, water and oil drained, here we go. Piston tops look good, cylinder head gasket like new.

All parts and especially the valves look good. The probable reason being the piston rings, I will have to dismantle the bottom end as well.
Cheers.