The Knowledge - Velocette Owners Club

and the wells underneath were full of oil I got gaskets from Nick Payton and since they have been fitted
and the engine cleaned to oil deposit around the cylinder head has not returned.
L #3535 Hi, Which sealant is best with the VSL rocker box gasket ? Light compound I use so far
is efficient, but this greyish stuff of the gasket takes hours to be rubbed off from the box and head. I
wonder if polymer compounds like loctite or 3 bonds used for timing chest are suitable.
#3536 Try a tube of Yamabond. It's made for just this sort of application.
#3538 I use the sticky grey stuff (Permatex Ultra Grey in the US) on the bottom side of the gasket and
peelable silicone seal Permatex High Temperature orange stuff) on the top. This allows me to reuse the
gasket since it stays stuck to the head while the rocker box will easily lift off. Clean it off with acetone or
methyl ethyl ketone (MEK), reapply the silicone seal, let it set overnight, and Bob's your uncle. I easily
clean off the sticky grey stuff with the acetone or MEK.
#3541 I have raced an MOV (alloy MAC head) for 7 years and KTT Mkviii for 4 and used no paper
gaskets anywhere. I used mainly Permatex Ultra blue 77B . Tappet covers were regularly removed and
replaced with no subsequent leakage. Good idea to smear on one side only, remove after 24 hours and
carefully remove any inside overflow. Threebond 1211 is a good Japanese product too but 2 ½ times
the price of the "blue". (retired from racing in 2002 but restoring Mk1 KTT NO 96). noted previous
discussions re oil, Castrol R SYNTHETIC was best, stopped cam and follower trouble on high revving
MOV. Plus advantage of several meetings use against regular disposal of "R" (vegetable.)
#3546 I use a smear of copperease high temp grease on both sides of the re-inforced rocker gasket on
my Viper. It doesn't leak despite being removed 4 or 5 times recently (thats another story)
#3553 Dodkin and Seymour recommended Green Hermatite on the rocker box - horrible stuff, but it
works. By the way research and personal experience leads me to recommend Blue Hylomar on ali to ali
surfaces, Welseal on most gasketed surfaces. Grease on the gearbox chain case gasket, Silicone
ONLY on exhaust flange to pipe and with care on rigid pushrod cups rocker box joints.
#3557 The service manual says, for the rocker box gasket, "Fit a new gasket; sticking this to the rocket
box with a light smear of grease, or Gasket Goo jointing compound."
L #3663Does anyone have dimensions of original MK1 valves. In particular the stem length. My
Mk1 valve seats have been cut down so low into the head over the years that we are uncertain how to
set the inserts close to original. If the present valves were fitted with new inserts we would have no
hope of achieving correct tappet clearance even with valve stem caps fitted. The head is in Melbourne
and I have not had a report yet if there is enough "meat" left to retain inserts. The seats may have to be
restored by welding which I believe is a very tricky technical job. There is an old timer in Melbourne who
no longer works. He used to build a coke fire and set the cast iron heads in the fire , heat the head, and
then gas weld the seats while still sitting in the coke fire. Unfortunately these old craftsmen are a dying
race. ( I refer to Melbourne as I live in Shepparton 112 miles North of Melbourne). Any advice of
previous experience with this problem would be appreciated..
#3666 I have just had a rummage in the attic and found 3 old valves, 1 inlet and 2 exhaust. They all
measure around 3.64 inches (3 41/64") I hope this helps.
L #3672 There is a 1 1/2" long steel exhaust pipe pressed into the head. Mine does not quite
bottom against the head, it leaves about a 3/32" gap with almost an inch protruding. I heated the head
up in the oven at 300F for an hour and whacked the pipe but it didn't budge. Should I do something
about it or let it be? The head is stripped except for valve guides, seats, and carburetor studs. I don't
know if the pipe has moved during use.
#3674 My Venom exhaust stub is similar to yours Mark, except the gap is more than 1/8". When fitting
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