Following problems getting up the steep hill to my house I found my 1932 SV minor had no compression on middle two cylinders so have set about changing the head gasket.
After a struggle with the head jammed on the studs, studs shearing off etc. I have removed the head and taken the valves out. Having had so much trouble I plan to have the head skimmed as a precaution.
On valve 4 (and to a lesser extent it's neighbour number 3 ) there is erosion of the seating surface on one side of the seat in the block. This is in the area where the two seats are very close together with only a narrow "land " in between.
Can anyone advise the best way to deal with this. Should I try grinding paste first or should I use a seat cutter to try to clean up the seat without excessive grinding.
What are the options if this fails - do I have to remove the engine , strip it down and ask a machine shop to fit seat inserts ? Can this be done with the SV engine ?
Any advice anyone can offer would be helpful.
Thanks
Mike
aka henry32
Side Valve Head overhaul - advice please
Moderators: Ian Grace, Will Grace
Re: Side Valve Head overhaul - advice please
Hi Mike,
Sorry to hear of your troubles.
For what it is worth, if the erosion is too deep to be ground out (and it sounds like it is), then re-cutting the seat would be your next line of attack. It doesn't matter if the land between the two valves disappears, as the valves don't get any closer and as long as there is plenty of mating surface with the valve heads, there is no problem.
Of course if all this fails, you are looking at fitting new valve seats, and therefore an engine-out scenario, but let's hope it doesn't come to that.
It sounds like the original problem was a blown head gasket between 2 and 3, quite common, and more so these days with these modern fibre head gasket which I personally don't trust. You might consider having the head skimmed and see if you can source an original Payen copper asbestos head gasket. What was fitted when you removed the head? Also, I would fit high tensile 5/16" cylinder head nuts. I get mine from from LAS Aerospace. The part number is A27-GP and you can find them at https://www.lasaero.com/products/article/X03A5OVA3. 69p each and they will tighten down hard without the nut thread stripping.
Anyone else have any thoughts for Mike?
Sorry to hear of your troubles.
For what it is worth, if the erosion is too deep to be ground out (and it sounds like it is), then re-cutting the seat would be your next line of attack. It doesn't matter if the land between the two valves disappears, as the valves don't get any closer and as long as there is plenty of mating surface with the valve heads, there is no problem.
Of course if all this fails, you are looking at fitting new valve seats, and therefore an engine-out scenario, but let's hope it doesn't come to that.
It sounds like the original problem was a blown head gasket between 2 and 3, quite common, and more so these days with these modern fibre head gasket which I personally don't trust. You might consider having the head skimmed and see if you can source an original Payen copper asbestos head gasket. What was fitted when you removed the head? Also, I would fit high tensile 5/16" cylinder head nuts. I get mine from from LAS Aerospace. The part number is A27-GP and you can find them at https://www.lasaero.com/products/article/X03A5OVA3. 69p each and they will tighten down hard without the nut thread stripping.
Anyone else have any thoughts for Mike?
Re: Side Valve Head overhaul - advice please
Thanks for your reply Ian.
Having looked at the seat more closely I am wondering if what I am seeing as bright groove is in fact metal sitting (melted ?) onto the valve seat.
The number 4 valve has a bright area at one point which almost looks like a flake of metal on the seat surface. I wonder if it is possible that a piece of metal has got trapped in the valve but can't imagine where it would come from.
Having read about the problems with valve seat cutters on the internet I think I will use conventional grinding at first until the seat cleans up (currently brown like baked on oil) and see how that goes.
As regards gaskets the one I took out was a copper sandwich type but it didn't look like asbestos in the middle - more a smooth black sheet similar to the new composite one I obtained from Ian Harris.
Were they always copper/ asbestos or did they use solid copper originally?
I'll let you know how I get on. Thanks for the assurance about the thin "land" - presumably if the seat goes deep the shallower angle at the top should be restored, as the valves look like "3 angle " shape.
Thanks and regards
Mike
Having looked at the seat more closely I am wondering if what I am seeing as bright groove is in fact metal sitting (melted ?) onto the valve seat.
The number 4 valve has a bright area at one point which almost looks like a flake of metal on the seat surface. I wonder if it is possible that a piece of metal has got trapped in the valve but can't imagine where it would come from.
Having read about the problems with valve seat cutters on the internet I think I will use conventional grinding at first until the seat cleans up (currently brown like baked on oil) and see how that goes.
As regards gaskets the one I took out was a copper sandwich type but it didn't look like asbestos in the middle - more a smooth black sheet similar to the new composite one I obtained from Ian Harris.
Were they always copper/ asbestos or did they use solid copper originally?
I'll let you know how I get on. Thanks for the assurance about the thin "land" - presumably if the seat goes deep the shallower angle at the top should be restored, as the valves look like "3 angle " shape.
Thanks and regards
Mike
Re: Side Valve Head overhaul - advice please
Hi
Seeing as this thread is focused on the side valve head, can I ask folk about the use of unleaded without after-market additives? Do these early design of engine suffer from valve seat recession caused by a lack of lead? I know the post-war A-Series OHV suffers badly without hardened valve seats but does a side valve engine? Thanks in advance.
Seeing as this thread is focused on the side valve head, can I ask folk about the use of unleaded without after-market additives? Do these early design of engine suffer from valve seat recession caused by a lack of lead? I know the post-war A-Series OHV suffers badly without hardened valve seats but does a side valve engine? Thanks in advance.