tobyd · Apr 4, 2015

Hi,

I have taken the head of my 3 bearing 2.25 petrol. Now its off I planned to have it skimmed. What else would be adviseable to do whilst its off (cheaply)?

How can I test the valve seats and pistons for their sealing qualities? (could it put petrol in the upturned head to see if it leaks out of the valves?

Should i need to fit new valve springs?

this it what I have.

Thanks for looking

tottot · Apr 4, 2015

Why is head off? Looks like it may have blown head gasket between cyl 1 and two?

tobyd · Apr 4, 2015

tottot said:
Why is head off? Looks like it may have blown head gasket between cyl 1 and two?

Thought the head gasket had gone!

tottot · Apr 4, 2015

Clean up head,check it's flat,skim if needed.[These old cast iron heads do not warp ease]
I would remove all valves to check them and valve seats,replace any that are pitted and then lap in all valves,fit new stem seals but springs should be ok if not broken.
All can be done at home except seat replacement and skim.

tobyd · Apr 4, 2015

tottot said:
Clean up head,check it's flat,skim if needed.[These old cast iron heads do not warp ease]
I would remove all valves to check them and valve seats,replace any that are pitted and then lap in all valves,fit new stem seals but springs should be ok if not broken.
All can be done at home except seat replacement and skim.

Can the valves be removed without a spring compressed?

tottot · Apr 4, 2015

Well I have in the past done it with a ring spanner and bar but it,s a hell of a lot easyer with a compressor and you are much less likely to hear the ping of a valve retaining collet vanishing into the distance.

tobyd · Apr 5, 2015

Can I jet wash the head to get rid of years of oil?

Castor · Apr 5, 2015

tobyd said:
Can I jet wash the head to get rid of years of oil?

Yep.

If you are trying to do the bare minimum, use Gunk or somesuch cleaner, or a jetwash and clean everything. Be sure you aren't driving crap into the inlet ports by stuffing them with paper towels or newspaper first.
Invert the head and fill the chambers with petrol - if it leaks you need to grind your valves. If not, replace head in the normal way, tightening in the correct order.

However! - strongly recommend getting a spring compressor and replacing the valve seals.

tobyd · Apr 5, 2015

Well the compression mystery is solved. 3 of the exhaust valves leak, 2 a little the other a lot!

oxides · Apr 5, 2015

If it's an unleaded head gently lap the valves in with some grinding paste (can you still buy the stuff? - had my tin half full for years....) If it's leaded consider getting the seats replaced. New seals is a must - they harden with age - I'm fairly sure there's minimum spring lengths in the landy manual. I'd also take off the rocker oil feed pipe and give it a flush through along with the camshaft and head oilways. Glue the rocker cover gasket to the cover with evostik before replacing to stop it slipping when you replace the cover!

tobyd · Apr 5, 2015

Managed to borrow the valve tool and some grinding paste!

Need to get on with it as keen to make it to the station meet at Bolton abbey station!

Been recommended Drakes in Bradford for the head skim. I am told I can get extra taken off to increase the compression ratio -does anyone know what depth the head would be for that?

tottot · Apr 5, 2015

A tap with a small hammer on the spring washer will help release collets before applying compression tool.

tobyd · Apr 5, 2015

Well everything is out and starting to clean up the head ready for getting it to someone who can skim it.

One of the valves has 2 cracks in it one you can see through. Will look to clean the valves to see how many new ones I need. Plenty of carbon build up to get rid of.

Whats the best way of cleaning the chambers that lead in and out of the cylinder from the manifolds?

Castor · Apr 6, 2015

oxides said:
(can you still buy the stuff? - had my tin half full for years....)

I have what is about to become a fourth generation double ended tin of grinding paste - my son wants to borrow it to do a job, and it has no chance of returning from that.... my father got it from my grandfather who nicked it from the WD in the early 1940's.
It's still more than half full......

dominicbeesley · Apr 7, 2015

The chambers shouldn't need anything special - a tooth brush anything to poke around with, though don't get anything harsh (i.e. griding paste) in the brass valve guides as they are quite soft.

I'd have a call round and see if there is a local engineers who will skim and fit unleaded valve seats while you have it apart. The valve seats will mean you can use unleaded and a n increase in compression is well worth while unless you're going to drive it in Africa or the 1970's - fuel in Europe is all high octane so can bear a decent compression ratio.

D

divie · Apr 7, 2015

If you are going to the effort of skimming get them to look at the valve guides. Simple to do and most likely needed. I am fortunate in having the kit to skim head and fit guides.

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