cylinder head

[BSAA10Richard]

I am sure you have been asked this before although a search doesn't bring an answer up
I have a 948 engine and the seats in the head are no good, having 8 new seats is not economical, I have been offered a head believed to be from a 998cc engine in reasonable condition, will this be ok to fit to my 948 engine, the only difference I can see is that it has a temp. gauge outlet which I can plug.

[philthehill]

The 998cc head will fit your 948cc engine without any problems.
What colour is the head - if it is yellow I believe it is already fitted with unleaded valve seats ex factory.
What is the casting number of the head which can be found on the top face of the head.
The casting number for the later 998cc head is CAM4810.

[BSAA10Richard]

Thank You I do not know the casting number or colour at this moment in time, but thank you for the information

[BSAA10Richard]

PXL_20240828_140010893.jpg (448.56 KiB) Viewed 5541 times

I bought the cylinder head today for not much money, It was a CAM4810 and it was yellow, although it needs painting again. The valves and guides are all good and I have lapped them in and checked the seats with engineers blue, so thankfully cheaper than fitting valves and guides to mine let alone the seats that needed replacing.
Can anyone tell me if the pop rivet that has been fitted by previous owner will be satisfactory, as on the 948cc head it looks to be a brass solid rivet

[philthehill]

That pop rivet needs to be replaced with a piece of brass rod or the hole threaded and a screwed plug fitted.

[Chipper]

I'm amazed at how little paint is left on it, considering it's usually very hard to remove!

[Chipper]

That pop rivet needs to be replaced with a piece of brass rod or the hole threaded and a screwed plug fitted.

Stop the press! New information on the later heads has come to light, and some were fitted with pop rivets from the factory:
https://minispares.com/article/Technica ... -head-2022

[philthehill]

The pop rivet may have been fitted at the factory but it does not make it right.
When the pop rivets were fitted BL was on its knees and any means of saving money was used. A pop rivet is much cheaper than a piece of brass.
There are lots of instances were BL tried to cut corners but got it wrong - for example rolled fillet crankshafts and the fitting of aluminium washers instead of copper washers on the classic Mini rear brake pressure limiting valve. BL had to recall all the Mini's so fitted and fit copper washers.
Personally if I had a head fitted with the rivet I would remove the rivet and fit a screwed plug.