Delloto 45 DHLAe quandary

[vxah]

Very interesting stuff there, I have read somewhere about a step up to bigger exhaust primaries from the port in order to reduce exhaust pulse reversion?
On the subject of choke sizes being too big causing loss of performance, why does this occur?
Is it because the throttle plates are open too wide for the progression phase to work any more but there is insufficient air flow through the choke to create enough depression to pull fuel through?
I was thinking that as the 45’s obviously have bigger bores and far more progression holes, would they allow for more air flow before having to move onto the main jets therefore allowing bigger chokes?
Or, is it because really, adding fuel through these little progression holes to only one side of the air stream is ok at light loads etc but poor for fuel atomisation / distribution when at higher loads?

[mbell]

Smaller choke, means higher air speed for the same volume of air. The main circuit is driven by vacuum/low pressure created by the air speed not total flow. So smaller choke should cause earlier engagement of the main circuit, possibly avoiding lean transitions.

The reverse problem is that a smaller choke can limit maximum air flow and therefore power at high rpms.

[Dellortofan]

Early on Vizard did a back to back test, weber vs dell. Ever since he recommended dell, newer design, more power.
Now more weber parts available with dell out of production decades ago.
He is on YouTube, powetec10 etc...

[Dellortofan]

One trick people have tried is a small drilling added in the butterfly. This is connected with the body drillings mentioned previously.
If you look at various carbs some are factory made.
As other people have said over carbing(venturi) is worse than under carbing.
Emulsion tubes affect air speed (the pull) and transition but a weber book will explain better than me.