Eric wrote:
> OK, so far I have heard nothing BAD about making this 'improvement' to
> HS6 (and thanks to all who have responded off-list), but then again I
> haven't heard from Barney, Ed, Larry....
Doubtful that I'm the Larry that you where referencing, but ...
>From what I've "read" (don't have a flowbench ... yet), the 1.5" carb
flows around 145CFM, and the 1.75" carb around 205CFM.
In "theory" the max flow for an 1800cc engine is 178CFM at 5600 RPM ...
(110 Cubic Inches x 5600 RPM)/3456 = 178CFM <--1800cc
(110 Cubic Inches x 6000 RPM)/3456 = 191CFM <--1800cc
(110 Cubic Inches x 6500 RPM)/3456 = 207CFM <--1800cc
(119 Cubic Inches x 5600 RPM)/3456 = 193CFM <--1950cc
(119 Cubic Inches x 6000 RPM)/3456 = 207CFM <--1950cc
(119 Cubic Inches x 6500 RPM)/3456 = 224CFM <--1950cc
... so (at 290CFM) the stock set of 1.5" carbs should be more than
adequate. However, this doesn't take into account the many factors that
directly effect the "theoritical flow" (flow characteristics of the
cylinder head, cam timing, valve size, etc.). Inlet valve, port, and
carb size all act to control the "gas speed" (flow) ... the larger the
diameter the higher the rpm when max "gas speed" (max hp) is reached.
In "practice" the 1.5" carbs are most effective for a street engine
(providing the best low to mid-range power) .. the 1.75" carbs are most
effective on a full race engine (providing the best mid to high-range
power). So, unless your bolting them onto a race engine (with a ported
large valve head) "don't bother"!
Just my $0.2 worth, YMMV
Later ... Larry
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