My New Project

  • Thread starter Thread starter Grant
  • Start date Start date
looks a good party, but too much dosh, it does show the difference between early and late block as I mentioned in my post (24th March) which Yogi probably didn't see.

It can be argued that the early gasket shape is superior, because the pressure over most of it is constant, whereas with the large and (cheaper to make) set up the pressure varies widely over the face, just look at the dimensions from the 12 stud holes to the edges , comparing both and you will (maybe) get what I am on about (maybe not)
CLEM
 
CLEMTOG said:
It can be argued that the early gasket shape is superior, because the pressure over most of it is constant, whereas with the large and (cheaper to make) set up the pressure varies widely over the face, just look at the dimensions from the 12 stud holes to the edges , comparing both and you will (maybe) get what I am on about (maybe not)
CLEM
Click to expand...

totally lost me
I have always believed Laverda changed the gasket sealing design at the end of 1977 solely because by then they were getting warranty claims on cracked cylinder heads
changing the sealing face on the barrels and the cylinder head was their first modification to stop the heads from cracking

there is no way I would use a small gasket head or barrel on one of our race engines
 
if you make the gasket surface area bigger but the bolts remain the same the "load" is spread over a wider area, this means that the pressure on the sealing  face varies across that bigger face, the earlier design comes closer to the pressure being the same at the important points, ie around the cylinders and the six oil bearing bolt holes.

The ideal is a bolt and copper washer scenario, but that is impractical on any cylinder head, look at most single cylinder air cooled engines and you will (usually) see four bolt holes and gasket that is of a given width around the bore, with that width being split equally where the gasket surrounds a bolt hole, with half of it on the inside and half of it on the outside.. To have a metal flame ring set in the gasket complicates things a bit, but to "crop" a half moon out of it to get an "O" ring around four of the six oil bearing studs is pure shite, and an "O" ring laying in a gasket???? they didn't have much faith in the sealing ability of it did they? plus the very first triples didn't have those "O" rings and they leaked oil as well, as did the crankcase halves, which was solved by the addition of an "O" ring in its own track.
CLEM
 
swap you then Clem, I have a number of small head gasket heads and barrels here, if you are so keen on them straight swap for later large gasket heads and barrels
I'll even pay the postage both ways so it costs you nothing
need some spares for the race engines and no way am I going to use a small gasket set up with the compression we are running


 
I'm not so sure Clem! If the head and barrel are perfectly flat then assuming that the bolts are tightened sequentially and in stages then the pressure should be the same all over the gasket upon completion.
Surely the factory had a reason to change things?

In an ideal world there would be no gasket at all! The thinner the gasket the better for long term sealing.

Steam turbine casings usually are metal to metal with no gasket and boiled linseed oil between.
We are talking of thousands of Psi pressure!
 
and many early Laverda's had metal to metal heads/cylinders such as scooters and maybe the 75's. You are correct Simon, I have built many steam boilers using only boiled linseed oil, and some of those flanges have to have washers for the bolts with a half moon cut out, to clear its neighbour. And on steam pipe falnges you cant use anything with paper, the best being brass "tailor rings"

What I am trying to suggest is pressure, given the same fixing, let us say a 16mm bolt, if a gasket has 40mm surrounding the bolt and is clamped between flat surfaces at a given torque, a given pressure is created, per square mm or whatever on that 40mm gasket, the pressure per square mm or whatever you like, will be lower if that gasket is 80mm and at 200mm on the outer edge hardly any pressure at all.
CLEM

thanks for the offer Red, but I don't have any to swap, and like Grant I also need a set of 1200 barrels, if I am correct they don't come in the "earlier" format.
 
Sooooo, back to the subject at hand, can now post some pics.

Got the previously painted rear mudguard stripped and polished, painted a tail light bracket and fitted a new CEV tail light.
Then ripped it all down to take the frame and some brackets for powder coating. Would have had it all back Friday if not for the Easter break.

2018-03-25 12.24.05 by Grant Duguid, on Flickr

2018-03-26 11.26.00 by Grant Duguid, on Flickr

2018-03-26 11.27.56 by Grant Duguid, on Flickr
 
LED globe huh, guard looks very nice way better than previous. Your a man on a mission, be an interesting head to head you and Maurice both starting with a box of bits at the same time to see who would get theirs done first.  :LOL:
 
This is the 4th or 5th I've restored starting with a bare frame. Next one will start with just an oil stain on the floor...
 
I tried one of those LED bulbs, had to buy a kit of 2. It lasted 2 days.Seemed a good quality. Back to std. Hoped it would work, low draw and brighter but at $35 for 2 days it worked, not happy
 
The ones I tried were from the local car accessory place,they were a well known brand, Hela maybe, no idea why they failed. But as I said expensive.
 
Quick update.
Frame and general black work all powder coated.
New swing arm and steering head bearings fitted.

Various parts ordered but still trying to find 1200 barrels, anyone?

Found an original shaved down primary cover, unique to early 1200s, prior to Marzocchi suspension update. Result! Had been considering having other type shaved down by CNC machining.

Bodywork away for painting, decided on the red option.

Still a very long way to go.

2018-05-03 12.41.12 by Grant Duguid, on Flickr

2018-05-03 13.30.45 by Grant Duguid, on Flickr
 
Grant said:
Quick update.
Frame and general black work all powder coated.
New swing arm and steering head bearings fitted.

Various parts ordered but still trying to find 1200 barrels, anyone?

Found an original shaved down primary cover, unique to early 1200s, prior to Marzocchi suspension update. Result! Had been considering having other type shaved down by CNC machining.

Bodywork away for painting, decided on the red option.

Still a very long way to go.
Click to expand...

Which red exactly are you planning to go for?
I'm musing about a gloomier red like RAL 3003 ...

 
Candy red.

The Corte e Cosso shock is temporary.
I will be restoring a pair of Cerianis for it as that is what the early* 1200s wore.

*
Cerianis front and back
Shaved primary cover
Cube fuel taps
Black vinyl Laverda decals on tank instead of badges
CDI ignition system
Thin web wheels
 
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