Will changing head gasket disturb the base gasket?

[SteveW]

Think my valve stem oil seals on either cylinder 1 or 2 are shot, if I take the head off to do them will this affect the base gasket?

[Nurse Julie]

Most probably. But, have a go and see.

[Cappodimonte]

When in the motor trade, I used a compressor connected to a heavy duty flexipipe which was in turn connected to a threaded insert mated to the other end of the pipe which fitted in the plug hole.

The compressor was set to 100 psi and allowed to build up pressure in the cylinder, with the rocker box off it was possible to use a socket that covered the valve spring top and short extension bar to ‘Shock’ the valve spring top with a plastic faced hammer to effectively make the two collets fall out.

The socket contains the collets stopping them dropping into the head, you’ll know success as you’ll feel the springs pressure on the socket.

Replace valve stem oil seals  using thin plastic wrap on the collet indents to prevent ‘cutting’ the new seals.

Replacing the springs was effected by using a 2inch long tube that was slightly bigger than the valve spring top, this had a small recess into it preventing the top moving out under pressure,, the tube had cut outs big enough to use a screwdriver coated with grease to relocate the collets.

The tube was welded to a foot long round steel bar that had a 4” wide ‘T’ piece that chest and body pressure was enough to compress the springs down to insert the collets, once both valves are done short rap with plastic mallet to ‘seat’ the collets.

Explaining this seems long winded but shorter than removing the cylinder head and possibly the  barrels to replace the base gasket as well as the head, it worked for me on over 50 applications
😀👍

[McCabe-Thiele (Ted)]

Reminds me of a RR/Bentley tool my late father had. You removed the spark plug feeding in the tool that had a curved section on the end. The body of the tool was the same thread a spark plug. By running a nut  down the tool this pulled up the tip of the tool against the valve. This prevented the valve falling into the cylinder. You could then depress the top of the valve to release the collets - change the stem seal then reverse the dismantling. It was used primarily for replacing broken valve spring a common thing in the 1950s.
I used it once on an A series engine in the early 1970s. No idea what happened to the tool in later years.

[Cappodimonte]

Another method is to put the piston at bottom dead centre, using a thin bladed screwdriver push in a soft cover rope until no more can be inserted, slowly wind the engine so that the piston rises and compresses the rope tight, using an overhead valve compressing tool you can compress springs then remove spring cover and collets..
The tool will keep springs compressed so that you can remove them, rope being compressed keeps valve in place, replace oil seal  then put compressed springs onto valve stem put collar back on re insert collets and unwind springs.
Finally wind piston back down the bore and remove the rope. Jobbie done.

[SteveW]

Thanks for the info, I had heard of the rope trick before. I’ll give that a try first.