Downdraught

[bsa-bill]

From the Heatblock post this thought occurred to me.


Now on a bit of a tangent re Tufnel, these spacers could be used to make a biased washer for carb re - direction (as I have done with thick paper type on my Flash and it does seem to work)), I wonder if they could be used to reduce the amount of downdraught on the alloy heads and would reducing this alter the bikes running much.
It would I thought give a bit more space between the carb and the top frame tube

[duTch]

 Bill, not fully sure what you mean by 'downdraught', I guess you mean the ~ 15˚ from horizontal (by my calculating)?
  In my quest to fit some kind of air filter to my alloy head on plunger, I made a inlet tract(Mk 2), which is about 4" or so long, and a 40˚ bend to the left and slightly down, so the carby sits where the battery should be. I think I'll have answers when I've done some distance, the Mk 1/90˚ version worked ok but I never did much mileage with it.
 

[muskrat]

 Yes Bill I have done that to correct bias. To lessen the downdraught would be OK and I doubt if many or any would notice the difference to performance.
Someone down here modified an alloy head by cutting and welding to reduce the downdraught. Fitted alloy head and concentric to A10 plunger. Mine has a little more room being an A7.
Cheers

[bsa-bill]

Thanks guys, sounds like a future option, probably try the gasket first but machining the manifold possibly a better option if some allowance for the angle of the studs was done

[trevinoz]

Why bother changing the downdraught angle, Bill?
Surely the engine designer knew what he was doing.

Trev.