I have a Holley 1904 on a 1955/56 GMC 270. On the bottom of the carb flange there is a vacuum outlet/inlet port that the gasket seals. Gaskets I have seen online have four cutouts that would appear to allow engine vacumm to connect to that port. I am getting terrible gas mileage- 6.1 city and 8.1 highway, have been thru several carb rebuilds. The engine runs fairly well, seems to misfire a little, and it backfires occaisionally on acceleration, and when I shut down the engine, there is a lot of gas vapor in the carb. The float level was off, still may be. Should I connect the vacuum port via gasket cutout?
Last edited by Dave Douglas 56; 11/17/2012 11:38 PM. Reason: spelling
Well, my time went so quickly,
I went lickety-splitly
Out to my ol' 55.
As I pulled away slowly,
Feelin' so holy,
God knows, I was feelin' alive..... Tom Waits, Ol' 55
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