Quote:
Originally Posted by AZKen
Speaking of Holley, the company that wants to sell you a carburetor and make money. Here is a quote from their Technical Section. I think they don't adhere to "calculations do not represent real world results. I think they think calculations are real world and "more than likely" is not real world.
"Use a carburetor with an airflow
rating equal to or slightly smaller
than the air requirement of your
engine."
Their chart shows a 305 Cu In motor with 4000 RPM needs a 297.5 CFM carb. Round up to 300. This calculation is at 85% VE which Holley states is a "High Performance VE".
My thought is not to convince anyone who wants to "carb up". My info is for new owners/members to have a second opinion backed by actual, real world info from Holley and others.
VE= Volumetric Efficiency
I am not comparing 2bbl to 4 bbl, I am talking about a Holly 500 CFM 2bbl on a 305 V6. Apples to apples. Putting a 4 bbl on one would be ridiculous.
Many of us, including me, can't get over our early days of 283's, 327's, 350's and putting on duals and a 4 bbl. We can't remember that in the 60's, fuel economy was not a real issue and V8 motors were build with some rev left in them up until 1972/73.
305 V6 is not that world. It is however a neat motor for reliability, nostalgia and correctness for 6066. For revs, no good, motor weighs 800 and all the rotating components are heavy except the aluminum pistons. That gives two obstacles for us speed freaks, rolling mass weight and rotating assembly weight.
|
Over the years, in my engine building and drag racing experience, I found many times that a carburetor with a larger flow rating than what was calculated made the car faster against the clocks.
Now, whether that was because of actual VE verses an arbitrary value of VE for calculation, I do not know. I, like you, did many 2 bbl to 4 bbl conversions along with dual exhaust and in all cases, saw a noticeable increase in power.
Even the lowly 6 cylinder Chevy reacted positively to an increase in breathing ability, just as a 305 V6 will.