The Knowledge - Velocette Owners Club

B.4. Timing Gear and Pushrods -
L #79 One way is to run the engine at tick over, and slowly screw out the adjuster until you just
feel the cam follower and valve lift lever (on the engine) make contact. Keep your hand on the lever,
you will feel when it makes contact. Back it off two to two and a half turns and tighten the lock nut. That
should give you 80 to 100 thou clearance. Check that the valve lifter works OK
L #81 My 1960 Velocette Venom is fitted with both the 0.010" and the 0.031" compression plates
on the cylinder base. Prior to my recent engine overhaul the tappet adjustment has always been at the
end of the useful travel with the adjusters screwed right through the rockers so that there is only just
enough tappet left for the nut to be tightened on. I have just renewed the valves, guides and springs
and had the seats recut. Very little recutting was required and the seats are in good condition, i.e. not
recessed into the head. When I torque the barrel and head using the info on Dai's database I now find
there is no adjustment left on the rockers at all. Did Velocette just have one size of pushrod for engines
fitted with or without compression plates or was this considered unnecessary. I could not find any data
on the length of the pushrods to allow me to check that mine are standard. Is this data available or
does anyone have a solution. The rocker arms are not significantly worn. I can always get longer
pushrods made up but I would prefer to understand first of all why the problem exists.
#82 I had a similar problem on the exhaust side of my Venom. On investigation I discovered that the
replacement Nimonic 80 valve was shorter than the original. This reduction in length was from the collet
groove the top of the valve. Apparently these were manufactured in this way to improve the valve
striking angle. The effect of recutting the valve seats, and settlement of the compression plates will be
positive regarding your adjustment problem. Remanufacturing push rods is not difficult. Use 0.325 inch
16 s.w.g. tube (I have the spec somewhere if you need it)for the pushrods, you may need to ream the
bore 0.250 to get the spigots to fit in the bore. I used high strength retainer as well as a precaution. By
the way there is a simple lever tool you can make to help you lift out and in pushrods without removing
the rocker box. Get a steel bar about 18 inches long and on one end drill to fix a bolt about 3 to 4
inches long that will fit into the hollow rocker spindle. Then drill the bar and fix a shorter bolt that will go
under the rocker. You can then lever the rocker up and lift the pushrod up to get the lower end out of
the cam follower cup, so that you can slide it out of the push rod tube
#96 I actually managed to track some pushrods down that were 3mm longer than mine that were just
the right size. I am now able to adjust the tappets easily, with plenty of adjustment to spare. Incidentally
I tried two different Velocette parts suppliers and their push rods varied by 2mm
L #272 Help/advice required from any LE cognizants I have twice had teeth broken from the
camshaft gear of my 1956 Mk 2 LE. I could find no reason for the first breakage, except that the gear
appeared to have had a broken tooth repaired on some previous occasion and perhaps the repaired
tooth let go and the bits took out a few of its neighbours. I then replaced the gear with another which
appeared in very good condition, but which had come from an LE which had burnt. Within 50 miles, two
more teeth broke on this gear, one of which was in the same relative location as one of the first. There
is no evidence of any seizure of the camshaft or tappets or valves, the pinion looked in worn but
reasonable condition, valve springs not spring-bound, valve heads did not hit the heads. In the second
case, the two broken teeth were on opposite sides, i.e., 180/ apart, leading to my thinking that the first
broken tooth had jammed in the pinion and done one rev to hit the opposite tooth, just a surmise. The
teeth are broken at the point of the camshaft rotation where the exhaust valve is in the fully open
position. I am looking for a replacement set.
L #674 I've just had a magneto overhaul and refitted it and done all the business with TDC
finders and degree discs. My problem is with refitting the auto advance mechanism. It came off fine,
the bolt loosening and tightening as it drew off the taper just like it says in the manual. Putting it back
on, the fibre gear meshes perfectly and the bolt screws on but goes solid about 3/8" before the bolt
head buts against the mechanism leaving the horseshoe washer and the round plate that locates on
the 2 little pins totally loose. I took the mag off about 3 months ago and I've never messed with an auto
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