Changing sf1 head for sf3 head

Mick brown said:
My sf1 has smaller inlet ports and carbs and valves than my Sf3 head
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Then it ain't no SF1 head... :D

Same valves, same carbs, same ports from SF1 -SF3.  Only difference were the cams.  And very late SF3 heads have one cooling fin less, or was it one more?

Small valve head engine is far sweeter... ::)

piet
 
You are right ,upon further investigation it is a 1970 SF head i dont now know if there is any advantage fitting the SF3 head and bigger carbs to the replica any opinions welcome.
 
Hi Mick - Heads (with carbs etc) are a straight swap - not sure what the smaller bore earlier exhaust pipes would do. We fitted a pair of 32mm PHF carbs to a small valve head - went exceptionally well! - I'm with Piet on not thinking it's worth the change. - Regards - Phil
 
but you cant put and SFC Eletronica head on an earlier SFC, due to the change in liner spigot height, and the relationship between the differing piston crowns, you could put head and barrels on though, not that this is relevant to the above, just pointing it out.

I think that I have heard it said, maybe even by Toddy, that the small valve head is more suitable for flowing and porting, and even the inclusion of big valves than is the SF1 to SF3 head?

did I bring you back a small valve head from France for that purpose Phil, purchased from Mr Marx, anyway me and POLO had a very nice lunch somewhere deepest in frogland even if his head was crap, lets face it if Marxy was selling would you want to buy!

CLEM
 
CLEMTOG said:
but you cant put and SFC Eletronica head on an earlier SFC, due to the change in liner spigot height, and the relationship between the differing piston crowns, you could put head and barrels on though, not that this is relevant to the above, just pointing it out.

I think that I have heard it said, maybe even by Toddy, that the small valve head is more suitable for flowing and porting, and even the inclusion of big valves than is the SF1 to SF3 head?

did I bring you back a small valve head from France for that purpose Phil, purchased from Mr Marx, anyway me and POLO had a very nice lunch somewhere deepest in frogland even if his head was crap, lets face it if Marxy was selling would you want to buy!

CLEM
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:D
I think I've sold Phil a few things. A lot less than he's sold me though.
That lunch was good.
Paul
 
I think that I have heard it said, maybe even by Toddy, that the small valve head is more suitable for flowing and porting, and even the inclusion of big valves than is the SF1 to SF3 head?
Click to expand...

That's right Clem - the small port head can be modded to get the inlet port angle closer to the valve angle (Downdraught) - both heads would take larger valves - I've fitted 44mm inlet and 37mm exhaust in them before. 'twas you who got  a small port head from Paul for me for my 860 project. - regards - Phil
 

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Hey thread hijack alert! Is it right that anRGS head is large valve? Have last new one in the world on the Joya as you know  :D
 
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