Reply to "Anand’s Faux Cam Spyder engine by Pat @ CB"

56widebody posted:

Also correct me if im wrong.  I thought the specs on Weber 48's were almost the same as Del 45's

Stan Galat posted:

edsnova posted:

I think you're right. I have heard somewhere that Del 45s are closer to Weber 48s than to Weber 44s. Del 40s are more like Weber 44s than Weber 40s. . . . No idea why this would be though.

Because the standard vents are bigger on the Dellorto 45s. Getting bigger vents for the IDF 44s gets them into the same ballpark as the Dellortos.

Bigger throttle plates present their own tuning challenges. Everybody is always worried about "how big" the carbs are, but a smaller carb with a bigger vent is nicer to drive than a great big carb with a small vent. Progression is just easier to control with the smaller throttle plate.

^^^What Stan said^^^  Comparing 40, 44/45 or 48mm Webers/Dellortos, when equipped with the same size venturis the carbs will have similar flow and hp #'s. People get all confused because 40 mm IDF's normally come with 28mm vents while the same size Dellortos have 30's or 32's, so of course it's possible to make more power with the Del's out of the box. Same with the 44IDF/45Del- bigger vents in the Del's give people the impression that they'll make more power (and they do), but equip the Webers with the same size vents and and now the carbs have very similar outputs. Both  carburetor series are very similar in design, and yes, the Dellorto has some slightly superior features to the IDF, but probably only a very experienced driver will notice, and only when the car is being driven close to it's limit.