The Knowledge - Velocette Owners Club

cams rotate through a generous cavity below the camshaft that would be full of oil, and this must fling
around the inside pretty well. Dave Poole noted that when he put a 17/11 cam in (from a Mk 8), he had
to mill out the inside of the head a bit, suggesting tolerances are close, and adding to the likelihood that
oil would get picked up by the cam lobe through every rotation of the shaft. Given this, I am surprised
at the suggestions that the oil feed is insufficient and contributes to early cam failure on the KSS. I am
going to do the oil feed conversion on mine next year just because it's cool and I want to mess about
with it. My curiosity is too great not to hook up gauge and see what is happening up there.
# VOCNA 233 I had my KTT cam go flat soon after I got it. Not quite sure why. Surely the more
aggressive cam profiles and spring pressures contribute. I had Gary Robinson stellite the cam and
followers back to /11 profile with 5/8 radius followers. Noticeable change, a bit soggier in the mid range
but a good wallop on top. Most of the long time cammy racers I queried still swear by bean oil. Not
wanting to deal with the hassle, I'm using Redline synthetic and so far no wear issues. I check the cam
feed jet (a bit different set up than KSS) for blockage on occasion and have kept the pressure gauge
installed, doesn't hurt anything and at least tells me I have pressure to the jet. Bevel drive set up is not
something I want to do on a regular basis.
# VOCNA 234 Bean oil is good! While at the Manx Grand Prix last summer I met an ex-Ralph
Seymore mechanic now retired and living on the Isle of Man. He took pity on me and took me under his
wing. One of my problems was cam, cam follower, and piston skirt scuffing. I was given a gallon of 50
weight Castro (not Castrol) oil. Castro is an organic oil heavy with caster bean oil. Anyway my scuffing
went away. Two problems though; One is being organic it separates and spoils if not run on a regular
basis. I left it in my engine until February and it smelled terrible when I flushed it out. Other problem is it
absolutely incompatible with Mineral oil and will form globs if mixed together. This year I've also been
using Red Line 50 weight synthetic racing oil with no wear problems so far. I was also told for push rod
engines, in addition to o-ringing the pump body and timing cover to oil jet interface, to open up the cam
feed jet oil holes with a .010" larger diameter drill and extend the rocker oil groove the full length of the
rocker.
# VOCNA 235 Were these considered racing mods? How does one put an o-ring around the oil pump -
that's a new one for me. I have rings on my timing jets, that's easy enough. The only reason I don't use
bean oil on my mkIV KTT is convenience, really. I use the thing quite a bit, and it pumps out copious oil
from the top end... and bean oil can't be found at the local gas station. On the summer rally, I'd have to
carry a case of bean oil, and although it smells great, its expensive. These are all now sounding like
really lame excuses... who's supplying it in the US, anyway? Also, when I switched the KTT OFF bean
oil, I used Redline Conversion liquid to flush the engine; I understand that Castrol won't glob up if there
is a little mineral oil, but your Castro has me worried.
# VOCNA 243 I didn't think of it until you asked, but, I believe the enlarged cam oil jet holes and
elongated rocker bearing oil groove are intended for racing. The O-ring mods simply improve the
efficiency of the oiling system. The oil pump O-ring mod is actually a rather old dodge. It is intended to
reduce or eliminate the cross port or external body leakage of the pump in its' bore. Experiences and
opinions vary, but, basically, many think there is a short circuit between the pressure and scavenge
ports of the pump. I am of the opinion that there are losses between the ports. Particularly if the pump
has been removed from the crankcase a few times resulting in the bore being out of round and/or
scored. The most common modification is to put a 1/16" dia. O-ring between the pressure and
scavenge ports. Some add two more O-rings on the outside of the pump ports. I have added the O-ring
between the ports on a few engines that had low oil pressure and observed an increased pressure by
about 2 PSI. I don't know who supplies Castro in the U.S. I tend to think the Red Line 50W is a more
practical alternative. Read Line states in their catalog "Even though Red Line Race Oils are straight
grades, their low temperature properties make them exceptional multigrades". The catalog goes on to
list the oil as "SAE 50 (15W50)". What all that means I don't know.
# VOCNA 239 Someone else may elaborate but the oil pump o-ring mod is very common, done it
myself a couple of times (I'm sure you'll find it in Tom Ross's compilation). Just turn grooves around
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