stumpshot

When I bought the 75 about 10 years ago I pulled the carb and put on a Edelbrock 600 and manifold. I threw the old parts, along with all the smog stuff on the shelf.
My buddy bought a 52 chevy and we were looking at the carbs I have. He said the old carb is a economiser. About a 400 cfm. Never saw one before, not many numbers on it but a great big Holley cast on the top.
Where did these things come from?
I know the 350 got great gas mileage with it ( better than the 11 mpg with the 383 and 680 QFT).

jb78L-82

I can actually shed some light on this topic. Back in the late 70's I bought a holley economizer/economaster 2 bbl for a 400 SBC V8 in place of the rochester 2 BBl during the second "gas Shortage". I ran that Holley 2 bbl for many years until 1990. Very reliable and improved the gas mileage over the rochester 2 BBL.

I still have the Holley 4 BBL economizer on the shelf in my garage all wrapped tight that I also ran in the mid 80's on a 350 V8. The Holley Economizer 4 BBl is a 450 CFM Spreadbore carb with 4 equal size barrels of the same size for the primaries and secondaries...they are tiny.and mechanical secondaries in place of the Qjet vacuum like secondaries. It worked well to improve mileage but also reduced full power due to the 450 CFM rating and the small secondaries. This carb would be a great 4 bbl for a small V8 like the 225 CI V8 buick sold to British Leyland for the TR8's and some other British cars, the 260/283 V8's and the GM 6 cylinder engines.......

The Holley 450 CFM economizer spreadbore with mechanical secondaries easily beat the gas mileage of the Qjet especially if you used a light foot to prevent the secondaries from opening.

I am curious if others had any real world experience with the Holley Economizer?

Hope that helps!