RGS Cylinder Head Wanted
- Thread starter IAG
- Start date
Lee87H
Hero member
- Location
- Upstate New York USA
arancia
Senior member
- Location
- Arizona, USA
Thanks, Lee-Let me know when able.
That doesn't look like a '76 head-looks like a later design. Thank you for posting!
helicopterjim
Hero member
- Location
- near Lone Butte, BC, Canada
arancia
Senior member
- Location
- Arizona, USA
Well, I'm not the seller so can't be sure, might be worth asking him, but it does look very similar to the two 3C skulled heads currently on my workbench and he's also selling cases numbered 2927 though doesn't state they are from the same motor.
It actually looks more like an RGS head than a '76 3CL head. I'm looking at the tappet guide bore area-earlier heads have a smaller cam lobe relief, cam blocks aren't square & guide bore edge separate from cover gasket flange, IIRC. Also, early inlet stubs have mount studs whereas eBay head has later style mount bolts & groove for manifold rubbers. Seller emailed.
helicopterjim
Hero member
- Location
- near Lone Butte, BC, Canada
I doubt it is a RGS/120° head, the inlet valves look a tad too small. Should be 39.5mm instead of the 38mm of the 3C et al.
This head has seen serious corrosion at some stage, combustion chambers look to be freshly blasted.
A 120 motor will also require the deeper locating groove for the cam bearings, otherwise cam assembly will turn into a nightmare. The pictured cam bearings don't look like 120 items either, but cannot be 100% sure without seeing them off the head.
Length of the front stud at the chain tunnel can also be a clue.
piet
This head has seen serious corrosion at some stage, combustion chambers look to be freshly blasted.
A 120 motor will also require the deeper locating groove for the cam bearings, otherwise cam assembly will turn into a nightmare. The pictured cam bearings don't look like 120 items either, but cannot be 100% sure without seeing them off the head.
Length of the front stud at the chain tunnel can also be a clue.
piet
Thank you for weighing in, I was hoping for an expert perspective. Chambers considerably pitted!
78jotadave
Hero member
'75 would have the early-type smaller gasket surface.
Not exactly sure when the larger surface was introduced, but definitely '76-'77>. There were usually a host of other integrated "updates" when castings were altered during production, eg, the wall thickness at the crack-prone chain tunnel corners was gradually increased with every alteration.
piet
That's the notorious all-alloy head, the guides were modified to suit. When the factory reverted to skulled heads, the original guide design was again used.
piet
The Sock
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- Location
- London, England
In Standard Practice Laverda Form: Although it may have been "introduced at 3887", mine is a later number and came with this head and barrel design.
