Zero Valve Clearance

[hendre]

I dug out my spare parts and to make things a bit more complicated there are two types... see pictures for differences and length (mm should read cm)

can anybody explain the two types?

[EVguru]

The ones on the left are early type. If you have a cambelt breakage and valve to piston contact nasty things will most likely happen!

The later ones don't have the ends pushed fully home so they are able to shorten and greatly lessen the chance of damage.

[spub]

Very helpful Hendre, thanks. I assume you meant 180mm rather than 18.5mm, which would be a very short pushrod, indeed....Doe this mean we have a "short" pushrod of 180mm, another "short" rod of 181.5mm which is also a "long" rod if used with the 180mm rod, and a "longest" rod of 183mm, which I assume is always used on the back??? Or is Morini trying to compensate for variations in valve seat depth, gasket thickness, and rocker/cam lobe wear??? I guess I'll find out when I get the two "short" rods from Stuart at NLM....

[hendre]

Very helpful Hendre, thanks. I assume you meant 180mm rather than 18.5mm, which would be a very short pushrod, indeed....Doe this mean we have a "short" pushrod of 180mm, another "short" rod of 181.5mm which is also a "long" rod if used with the 180mm rod, and a "longest" rod of 183mm, which I assume is always used on the back??? Or is Morini trying to compensate for variations in valve seat depth, gasket thickness, and rocker/cam lobe wear??? I guess I'll find out when I get the two "short" rods from Stuart at NLM....

All depends on what is in your engine now... you can easily see the difference in the top part. I would go for later type rods if they are already in your engine just in case the belt brakes...

And yes, the difference between the long and short rods is 1.5mm, later types are 1.5mm longer in all... so:
early type: 180.0mm short, 181.5mm long
later typeL 181.5mm short, 183.0mm long

[EVguru]

I seem to recall there may also be a difference on the pushrods for kanguro engines, perhaps even for all Gilardoni barreled 350/400s.

I have to say though; pulling the head on a Morini twin is so easy that I'd be inclined to have a look. You can nearly always re-use the metal head gasket (annealing it is a good idea). Use a VERY small bead of silicone sealant, about 1mm diameter.

[kangurada]

I've just measured a set from a 1984 Kanguro X and the pairs are 183mm and 184mm - catering for different camshaft?

[spub]

Update: Received 2 pushrods from Stuart at NLM that measured 180.15mm. With these is was able to bet the .10mm clearance, but little adjustment left on screws on the pushrod side of rocker... could have used the 180s, I guess, and had more adjustment, but you have to go with what's available....Noted quite a bit of play in metal piece that has the cup on the bottom of one of the old pushrods; a sliding play between the rod and this piece of 3-4mm. This was causing some gouging on the rod, and it appears if left this way the rod would eventually have failed....it appears these pieces are press fitted together, and perhaps swagged on the end.