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#1
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The following post was written by a friend of mine who occasionally reads postings here but is not a registered user. He has a flow bench and has done some experimenting with the Pontiac Tri-Power.
The 65 center carb flows 278cfm, the outside carbs and the 66 carbs are 435cfm. The 2 barrel carbs are flowed at 3 in. of Mercury and 4 barrels are at 1.5 pressure drop. 1 inch of Mercury equals 13.6 in. of water. To convert 2 barrel cfm rating to a 4 barrel you need to divide the 2 barrel rating by 1.414. So a 66 trip flows 923 four barrel cfm's The biggest improvements to the tripower is to take the air cleaners off and put a 1" phenolic spacer under the carbs. The air cleaner base must be left on the carb. These mods. on a 65 goat with a 9:1 400 picked up a half second in the quarter mile. 3/10s for the air filters and 2/10s for the spacers. A 4 barrel setup will out perform the tripower only because the manifold is better not the carburation. Headgaru
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Tim Corcoran |
#2
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More info Re: Tri-Power
The following post was written by a friend of mine who occasionally reads postings here but is not a registered user. He has a flow bench and has done some experimenting with the Pontiac Tri-Power.
The 65 center carb flows 278cfm, the outside carbs and the 66 carbs are 435cfm. The 2 barrel carbs are flowed at 3 in. of Mercury and 4 barrels are at 1.5 pressure drop. 1 inch of Mercury equals 13.6 in. of water. To convert 2 barrel cfm rating to a 4 barrel you need to divide the 2 barrel rating by 1.414. So a 66 trip flows 923 four barrel cfm's The biggest improvements to the tripower is to take the air cleaners off and put a 1" phenolic spacer under the carbs. The air cleaner base must be left on the carb. These mods. on a 65 goat with a 9:1 400 picked up a half second in the quarter mile. 3/10s for the air filters and 2/10s for the spacers. A 4 barrel setup will out perform the tripower only because the manifold is better not the carburation. Headgaru
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Tim Corcoran |
#3
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just dug up this old one. why would keeping the bottom air cleaner pan help?
and is it fair to say that a spacer might help 1/4 mile and higher rpm- but would hurt low end and stop light to stop light? |
#4
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Bases on factory air cleaners generally have a curved entry into the air horn not an abrupt 90 degree. This gives smoother air flow into the carb and thence likely more air flow with less or no turbulence through the venturi.
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#5
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2 BBL carbs are tested at 3.0" of Mercury or 40.78 inches of H2O
4 BBL carbs are tested at 1.5" of mercury or 20.392 Inches of H2O So agree there. We know the 1966 center 2BBL carb has a smaller Venturi diameter but a larger Throttle Blade diameter vs the 1965 center carb. And as posted several times, The air horn entry is better on the 1966 center carb. The Pontiac TRI-POWER air cleaner (Big Car) was a very good piece. What Flow Bench does he have Tim?? Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#6
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Hi Tom, he made his own flow bench but it's calibrated same as any other but I know there are still variations between benches even the professionally made ones.
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Tim Corcoran |
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