just wondering if anyone has had any trial and error experience or good luck - bad luck using one of the aftermarket 500cfm 2gc carbs on a small v8 ? thinkin it may be a possible alternate carb using an easily available 2bbl manifold on a mild 300 size v8 . a little cold air help , a little port matchin and runner work and it may be ok plus be a little sneaky lookin . ? . del
Del, Holley made several different sizes of the 2 bbl carb, but there is a reason that the 4 bbl is just two 2bbrls cast back to back.... when you up the cfms on a 2 bbl you still have to keep it within the same air/fuel ratio.... thus increasing fuel consumption... this is why it is possible to run a 4 bbl and actually pick up gas mileage... you can run the fronts leaner than the backs... cant do that with a straight 2 bbl.... now that said.... take a look at the holley 2 bbls that are designed for big trucks... they are set up to get mileage as much as possible and still feed a big engine.... that is they have a economiser valve/ power valve in them... and a setable accelerator pump... lot of good possibilities here... as long as you fully understand the benifits/limitations of the 2 bbl carb....I saw one guy put a 2 bbl on a car that was running a 4 bbl and it ran much better.... would burn rubber and would not before the swap... i would open up the bores in the intake manifold.... either by cutting the partition from between the barrels or enlarging the individual holes... it will improve the overall breathing...Remove any baffels in the air cleaner assy. and hook up a ''cold air'' pkg the the air cleaner snorkel... and make the snorkel bigger... it kills me how the factories have a v8 engine breathing thru a hole that is a in. and a half....the snorkel on a 300 would need to be at least 3'' and 4'' would be better... also keep the heat in the intake manifold, on a 300 it is water heated if I am remembering right,,, that is the best set up....you might restrict it , but dont remove it entirely,,,, a 2 bbl intake would definitly benifit from a port match/porting job but be very carefull here or you could ruin the manifold,,,, just smooth up , dont ''hog out''..... just a little increase in port/carb size will definitly improve performance... Use a 180 deg. thermostat, that is what was normal back in the day... recurve the dist... lot of performance for a little effort and effort.... Go to a good electric fuel pump, cuts the fuel heat...use a ''big truck'' type fuel filter that has a spin on filter....works much better....take the ''sock'' off of the pick up in the tank, the big filter will catch any crud....
i have not used the Rochchester 2gc carb at all ,,,, because my mom had a olds that used one and it would puke gas out all over the engine without warning.... put several kits in it and never did stop it from doing it.... finally I told her the next time it did it , dont call me....call anybody else but dont call me.... she traded the car on a Buick Centurian.....:laugh: :laugh:
had a holley 500 ( #4412 - about $40 brand new in 1970 ! ) on a 1965 300 special motor - i was just a kid , first car , did it myself - but hey - it worked ok and looked pretty good too with nice chrome air cleaner . just thought maybe the 2GC would be sneaky and maybe work just as good , i've had ok luck with those , had one puck gas all over my '68 lesabre 350 but a quick simple rebuild on the front porch at college and good-ta-go . i figured all the normal/not too crazy air flow "tricks" would be beneficial . del
