Quote:
Originally Posted by ericwy
Does the 6213 really flow 800 cfm? Its using a 4165 main body with with the same
1-5/8" primary and 2" secondary throttle bores as its 650cfm 4165 cousins. The only
real difference I can see is the secondary venturi diameter. 1=3/8" for the 650cfm 4165
vs 1-23/32" for the 800cfm 4156s.
Does the bigger secondary venturi diameter really allow an additional 150 cfm?
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just diggin' around, nobody answered this ?
seriously...
assuming it was a serious question...
hell yes...
1-3/8" = 1-12/32"
so it's 1-23/32" vs 1-12/32" venturi comparison
that is 11/32" bigger secondary venturis in the 800 carb.
that's a LOT, easily 150 cfm. over a quarter inch wider venturis
.344" larger venturis
a 1-3/8" venturi only needs a 1-1/2" or 1-9/16" throttle plate to close it.
they were obviously only using the same baseplate to save on mfg. costs.
the venturi has more effect on the flow than the throttle plate.
the venturi sets the flow, that's the restriction at WOT
the throttle plate just turns it on and off tp varying degrees,
from min to max
even 1/16" bigger makes a difference,
that difference in the secondary venturis alone,
is what makes a 750 main body, into a 780/800 main body,
that and 2 or 4 downleg boosters.
4 downlegs and 1/16" larger rear venturis makes a 750 into a 780 (list 3310-1 VS)
2 slightly thinner rear downlegs and 1/16" larger rear venturis makes a 750 into an 800 (list 4780 DP)
so if you're adding 11/32" per venturi in the back, you're adding a schitload of flow.
looky here below, 650 vs. 800
pretty obvious...as easy as girlwatching actually, easy peazy, which ones are bigger