big cams cylinder head?

michipons

michipons

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Location
Palma de Mallorca
Hi!

I found this cylinder head in Subito:

https://www.subito.it/accessori-moto/laverda-750-sfc-sf-1974-ragusa-343824951.htm

Does it fit my sf3? I heard there were different options... I believe this is the big valves one.

Is there any italian in the group that would help me speaking with the owner? He has no whatsapp or soever, so calling is the only option, no google translator for that case ::)

regards
Miguel
 
It?ll fit your SF3 all right. Expect it to be an SF2 or SF3 head, if it?s a (1974) SFC head, it will fit too, would be a bonus because it flows lots better.

Marnix
 
More attention was given to the porting of the head. The SFC had 7mm valves instead of 8mm, the inlet of the head itself (not the manifold) measures 36mm instead of 34.

Marnix
 
Looks very much like an SF1 head, Miguel - so yes, big valve. The SF1 had meatier rockers (vs what look to be forged thinner rockers on SF2/3).

The carb inlet will measure 36mm but at the entry to the head (after removing the alloy stub and black heat spacer) I'm betting it will be 34.5mm. It was a double venturi system.

Nothing wrong with that - otherwise SF1/2/3 are identical. Doubt very much it is an SFC head.
 
michipons said:
??? ???

So you mean that is not an SFC and is way to expensive? :LOL:

Miguel
Click to expand...

Don't worry, the price is what somebody will pay.

I have a few small valve heads and would like a lot less than that but they're much more common than the large valve heads.

Paul
 
the small valve heads have better scope for tuning than large valve heads, including fitting larger valves than large valve heads.

I now all that because A mate of very near 45 years told me, a certain Mr P Todd

It follows therefore that the small valve heads should be the more costly to buy.

CLEM
 
CLEMTOG said:
the small valve heads have better scope for tuning than large valve heads, including fitting larger valves than large valve heads.

I now all that because A mate of very near 45 years told me, a certain Mr P Todd

It follows therefore that the small valve heads should be the more costly to buy.

CLEM
Click to expand...

Seems you picked up a small valve head from me for Phil a few years back for the price of a few pints.

We had a nice meal somewhere.

Paul
 
I got my small valve head from Wolfgang at a very reasonable price. Big valves and 7mm guides are in, stud sizes increased to M8. Inlet angle has been altered by 10 deg but porting is still to be done. In hindsight I would have preferred to leave the head angle and raise the inlet port - probably similar to what Julian is doing, but less extreme (eg not changing valve angles and welding up holes).
 
CLEMTOG said:
It follows therefore that the small valve heads should be the more costly to buy.

CLEM
Click to expand...
Maybe it should, and maybe one day it will, but up till now the small valve head are the dirt cheap ones.

Marnix
 
Yes I've had some very good performance enhancements from starting with the small valve head with 10? angle reduced betwixt port and valve. - Regards - Phil
 

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Do those carbs slip off or do you have to remove manifolds
Click to expand...

just about able to get them off - the manifolds are triple ones laid sideways - so a tad shorter than the originals. - won't be a problem on my Sidlow SF!-  Regards - phil
 

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