I have a '67 289 "C" Code, automatic and I want to replace the carb. The engine is stock and I would like to eventually upgrade it a little more but I was wondering if I should go with the Holley 570 4 BBL. I heard Elderbrock was good but which one would add most HP and gas saving?
Markp
CFM = Cubic Feet per Minute
Carburetors work on vacuum. You need to look at the CFM your engine PULLS IN and then choose your carb off of that. Smaller CFM carbs give better low-end torque and fuel economy. Larger CFM carbs give better peak HP and torque numbers by sacrificing low-end. This is because the lower CFM carbs have higher air velocities which results in better fuel atomization and a better volumetric efficiency.
Summary:
Higher CFM:
Higher peak numbers
Slightly lower fuel economy
Lower CFM:
Better low-range and mid-end torque
lower peak numbers
slightly better fuel ecomony
289s came stock with the Autolite 4100. The 4100 has often been referred to as the best carb ever made. It came in two varieties (mainly) and they are the 1.08venturi 480CFM version and the 1.12 600CFM version.
The 1.08-480CFM is a PERFECT match for the stock 289. You can go higher on CFM and the engine will run just fine. You can get better peak numbers this way.
The 600CFM carb is about the biggest you would ever want to go on a 289 or 302 without heavy engine mods.
570 would work well.
-Matt
Carburetors work on vacuum. You need to look at the CFM your engine PULLS IN and then choose your carb off of that. Smaller CFM carbs give better low-end torque and fuel economy. Larger CFM carbs give better peak HP and torque numbers by sacrificing low-end. This is because the lower CFM carbs have higher air velocities which results in better fuel atomization and a better volumetric efficiency.
Summary:
Higher CFM:
Higher peak numbers
Slightly lower fuel economy
Lower CFM:
Better low-range and mid-end torque
lower peak numbers
slightly better fuel ecomony
289s came stock with the Autolite 4100. The 4100 has often been referred to as the best carb ever made. It came in two varieties (mainly) and they are the 1.08venturi 480CFM version and the 1.12 600CFM version.
The 1.08-480CFM is a PERFECT match for the stock 289. You can go higher on CFM and the engine will run just fine. You can get better peak numbers this way.
The 600CFM carb is about the biggest you would ever want to go on a 289 or 302 without heavy engine mods.
570 would work well.
-Matt
The Holley 570 street avenger would be a good fit on your engine. These carbs do not flow what they are advertised at. This carb will flow closer to 500 cfm; maybe a little less. Venturi size is what is important. I believe I've seen that the 570 street avenger has the same size venturi's as the Holley 465.
The 1.12 4100 used on the 289HP was probably around that size, and mine runs like a scalded dog.
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289s came stock with the Autolite 4100. The 4100 has often been referred to as the best carb ever made. It came in two varieties (mainly) and they are the 1.08venturi 480CFM version and the 1.12 600CFM version.
Unfortunately, I'm the second owner and the previous owner sometime a while back thought it would be better to put in a different carb (one with 2 BBL) and I have no idea what it is (there aren't any #'s on it whatsoever). Thanks for the information, I want to get this thing back to original shape and better
irate:
Unfortunately, I'm the second owner and the previous owner sometime a while back thought it would be better to put in a different carb (one with 2 BBL) and I have no idea what it is (there aren't any #'s on it whatsoever). Thanks for the information, I want to get this thing back to original shape and better
irate:If we make a few assumptions to determine your cfm requirements...
Max rpm seen...5500
max Volumetric efficiency....90% (most street vehicles are 80%, a hp version is 85%....so we are being just a little optimistic)
About 415 cfm.
FYI, this would be for a 4V carb, the 450-570 cfm units will work well- I just would not exceed 570 because you would likely have to reduce the fuel jet sizes.
Max rpm seen...5500
max Volumetric efficiency....90% (most street vehicles are 80%, a hp version is 85%....so we are being just a little optimistic)
About 415 cfm.
FYI, this would be for a 4V carb, the 450-570 cfm units will work well- I just would not exceed 570 because you would likely have to reduce the fuel jet sizes.
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