Square four overhaul/valve guide seals etc.

[daveleek]

Heres a link to an interesting video , fitting valve seals to a Citroen twin cylinder head



https://fb.watch/iSeZbXGFCp/

[allan.walker]

That's the tool for the job, for sure. An easy task for someone with my skill set....

I've tried googling VGS and so far, have drawn a blank.

I'm also trying a different approach, by trying to find valve stem seals which are the correct size for a Square Four. (I've been assuming that the existing guides will need to be machined, but maybe not....) Looking online, I have found one supplier (Elring) which lists seals by dimensions. When I get a chance, I'll have a good look.

edit: I've found many references online about 2CV valve stem seals, available off the shelf, together with tools for fitting them. It does make me wonder why the chap in the video was machining the guides to accept seals......

[daveleek]

When I had my Sq4 cylinder heads valve seats recut the shop asked if I would like valve seals fitted , I declined the offer ,in hindsight maybe I should have.
VGS are 2cv specialists in Belgium , the head they are doing is from an earlier 60s engine which didnt have seals fitted, later engines do have them, they can get very hot when not moving in the summer ,though not quite as hot as a Sq4

[allan.walker]

Ah, I see, that explains the need for the special cutter.

I've found VGS' website now https://vgs2cv.be/en/tool-klep-seal-AZ-M4-p531340456 and the special cutter, as shown in the video.

I'm hoping that I will find some suitable seals which will be the right size for the Square Four without the need to machine the guides.

[fpassmore]

Ahhh, this is very interesting information. I have a MkII head rebuilt by Mike Tadeo in California before he passed during the pandemic last year. I would like to install seals before putting this one in service so I will look at the seal suppliers for drawings on the machining dimensions for the guides.
I have a second MkI head I picked up for very little cost but three of the valve guide holes have been welded up so I need drawings that will have the necessary dimensions so I can have the new holes machined properly for new guides. Perhaps Roger can advise if such drawings are available?
Frank

[allan.walker]

Hi Frank,
I've realised one important fact. The o.d. of the valve guide is 14.1 mm. The i.d. of the inner valve spring is 16.3 mm (quick measurements with a caliper.) Therefore, there is no room for a seal around the top of the guide. The tops of the guides will need to be reduced in diameter so that a seal which fits that smaller size will have adequate clearance from the valve spring.

I was looking at Norton Commando guide oil seals. They have the same valve stem diameter as Square 4 valves, but the tops of the guides are a smaller diameter than the rest of the 'body.'

Therefore, something like the VGS tool, as mentioned by Dave Leek, would need to be used. I don't fancy spending 265 euros + shipping + import taxes for a tool that I would probably never use again! I was hoping that Mike Loehr would drop-in to this chat at some stage to explain how he machined the guides on his Mk2.

Allan.

[fpassmore]

Yes, some clarification would be useful in guiding the next step. I imagine it is easy enough with new guides to machine before insertion but removal to size correctly then re-insertion is a lot of work although not the worst I have done.
The MkI head I have will require all new guides once it is machined properly so that is fairly straight-forward.
Frank

[paul.jameson]

We do have the drawings for the Mk I head. You need ET/1288-1 and ET/1288 - 2 so you can email Roger and ask for them.

[mike.loehr]

Revisiting the valve guide seal posts for the Square 4,this process is not rocket science but does take a good hand in the machine shop.No need to buy those special tools.I used a small boring head in the mill and grind my cutters to suit the need. One tool cuts the diameter and also the depth needed to fit these seals.The seals are from the Harley Davidson EVO 1340 engine as they are the shortest seals available for that diameter stem.Too much detail to put in a post but I will help anyone with how to determine installed spring height,set up and machining.I have been busy in the shop and have neglected reading the forum post which I will pay more attention.Always like to talk Ariel 4.We have developed a digital electronic ignition system for the 4 along with my carb update and heading to the dyno room as we speak.Will post results at a later time.
Mike Loehr

[allan.walker]

I'll have a word with my retired machinist friend. He'll tell me if he has the tools for the job.

Looking forward to your reports on carb and ignition.

Allan.