GR thanks for the continuing information on cams; i very much appreciate your sharing, and your patience for answering my dumb questions.. Here is another one for you.. ( he says pushing his luck)..... are there flow 'quality' differences ( not quantity) in what the downdraft wants as opposed to the DCOE.... does it work better without having to worry too much about the aux venturi signal ?

Hi FNQ
Not sure what you mean by quality differences but there is no difference in the way the 2 webers work, the critical part of the weber is the distance from radius on the choke to where the fuel enters the air stream (axu venturi ),this is where it gets it's signal from, and this is where people get into trouble when they bore out the chokes to a bigger size and don't know what they are doing it will cost you HP.
This is why you see people having trouble getting the weber to clear it self from low rpm with a big cam, as you have a pulse going back and forth in the carbie and the venturi can not tell the difference between the pulse going in or the pulse going back out so every time the pulse wave passes the venturi it will drag a heap of fuel out, which causes over fueling until you get some RPM on board.
Graham Russell

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"It's better to be not informed than ill-informed"

Thanks Graham
That answers my questions perfectly and also satisfies my "engineering" curiosity.

I have another question ?
With the valve guide boss removed, the valve guide still presents an obstacle for the gasses to flow around. Would there be a benefit in retaining the guide boss but grind the sides of it away till you reach the guide. It could be shaped to provide an "aero" effect to guide the gasses in the direction you want them to go and smooth the flow past the guide. A simple round guide is terrible for air flow and this is why they reshape the butterfly spindles. Just wondering if the same principle for the valve guide and boss has merit.
Phil

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Find a job you love and you will never have to go to work !

Hi Phill
The valve guide in a mini head is a funny thing, i'v tried all sorts of things with the guide and boss,i'v tried building up the guide with bog to make it look like an aero wing but all it did was loose flow, in many cases the big guide helps to slow the air to help it turn the corner and flow around the dia of the valve and not across the back of the valve.
As for thinning down the butter fly shaft very minimal increase in flow no HP gain but what I have seen is the shaft bend when backing off at high RPM the vacuum trying to suck the butterfly down the bore.
Graham Russell

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"It's better to be not informed than ill-informed"

All right, stop the shining, the post is up. Go have a look and you can all hassle GR to get on with Pt5. Gets him off my back....

www.russellengineering.com.au

Cheers
Aaron

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Thanks for the next write up. looking forwarded to the update on the 266s and slightly modified head.

Yes cheers again ! Looking forward to trying to replicate this soon

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Simonw
Brisbane QLD
1st car - 1964 Mini Panelvan 850
Previous - 1978 Leyland LS 1275 Gold
- 1969 Mini K

Liking pt 4 0 thanks again gr and aaron

Hey don't thank me, all I do is hold him up, apparently.....

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Does he fall over a lot
What's in all that tea

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Find a job you love and you will never have to go to work !

Sugar, Lots and lots of Sugar.

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Sugar makes you fat, but he's not. Please explain....???

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Meth

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

The only thing fat that i can see is that torque curve graph

It's the nervous energy...Worry,worry...