Carburetor Size

[MBillings]

When I updated my engine from 1600 cc's to 1915, I was told by the builder of my cylinder heads that if he were building the engine, he would build it using a 44 mm weber carburetor. I have a 40 mm weber and had planned this winter to update to a 44 mm and dyno test the improvement.

I talked to my local carburetor expert, yesterday, and he said the 44 mm carburetor would hurt (drown) the low end performance. Now, I'm unsure what to do.

Does anyone use a 44 mm carburetor? Has anyone dynoed their engine (with a 40 or 44 weber). Has anyone done a side-by-side comparison of 1915 cc engines with the two carburetor sizes? How about a 1600 cc engine comparison?

I'm looking for data.

thanks,
Mike

[Lynn]

My engnine builder said to use a 48. So, we took the 48 off the 1600 which ran a little rich and put it on the 1914 which runs really, really rich. Sooner or later, we will be dyno testing with the 48 and two 44's. One 44 is brand new and the other is from the infamous "128 hp" engine.

[Vernon Maxey]

Hi Mike,
I have a 44 weber on my 1914. It has a 34mm vent, 165 main gas, 165 air cor, using 100 oct VP fuel, timing 16 ad to 36. On the dyno 98hp with
105 tor at 5200rpm vz 25 cam. Still did not match up to the 500s.They ran Formula Ford times at Nationals.
v.