whats the main differance between the regular 750 vacuum holly vrs. the truck avenger is the main dif the tube that connects the two vent tubes and what would happen if a person were to bend a tube that connects the two vent tubes. would it help with the flooding out when 4 wheeling
Holley Truck Avenger Carburetor yes/no ?
- Thread starter nordwind
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Do you mean a 750 cfm with center pivot fuel bowls vs the side pivot with transfer tube fuel bowls of the 670 cfm Truck Avenger?
They're apples and oranges.
The 750 is a larger carb for air flow. It's not going to run out of fuel like what I described was happening with my 670TA on my 454 V-8 pickup because it has a separate fuel inlet for each bowl.
The 750 may or may not have a secondary metering block between the carb main body and the fuel bowl. The 670 has a metering plate inside the fuel bowl.
The unique vent tube of the 670 is supposed to keep fuel from flowing from the vent stacks at extreme angles. However, some off roaders will simply put fuel hose extensions on their vent tubes.
The 670 also has anti-backfire power valve protection, whereas the 750 may or may not depending on when it was made.
The 670 also has annular venturis (notice the "skirt" at their base) that's supposed to give better mixture distribution even at low speeds. My opinion is this doesn't amount to a hill of beans if the carb is oversize for the engine.
They're apples and oranges.
The 750 is a larger carb for air flow. It's not going to run out of fuel like what I described was happening with my 670TA on my 454 V-8 pickup because it has a separate fuel inlet for each bowl.
The 750 may or may not have a secondary metering block between the carb main body and the fuel bowl. The 670 has a metering plate inside the fuel bowl.
The unique vent tube of the 670 is supposed to keep fuel from flowing from the vent stacks at extreme angles. However, some off roaders will simply put fuel hose extensions on their vent tubes.
The 670 also has anti-backfire power valve protection, whereas the 750 may or may not depending on when it was made.
The 670 also has annular venturis (notice the "skirt" at their base) that's supposed to give better mixture distribution even at low speeds. My opinion is this doesn't amount to a hill of beans if the carb is oversize for the engine.
Nordwind, Brian has given you some very good advice.....if you must stay with Holley, go with the 470. Having said that, I agree with your friend from post #1. You have a 383 truck motor with gobs of low in torque which is a great choice for a FJ40 on and off road. Nothing will kill that great low end faster than slapping on a carb that's basic design is for WOT performance. I'd recommend a Quadrajet....or take two hours out of your life and ask your friend. Like you said "He knows carburetors"
The Holley Truck Avenger with 470CFM says the following in its information:
Notes This carburetor is not designed or intended for use on any V8 application.
However by doing the math it looks like it would be the best size of the Truck Avenger series for my mild 350. ???
Notes This carburetor is not designed or intended for use on any V8 application.
However by doing the math it looks like it would be the best size of the Truck Avenger series for my mild 350. ???
Great Info Brian..
We are starting to build a GM 308 (aussie) and had been considering an avenger, but now I think I will stick with the stock quadrajet tuned for low end work..
Can you recomend what cam I should use.. (sorry about the hi-jack)
Gaz..
We are starting to build a GM 308 (aussie) and had been considering an avenger, but now I think I will stick with the stock quadrajet tuned for low end work..
Can you recomend what cam I should use.. (sorry about the hi-jack)
Gaz..
I sent a technical question to Holley about this. Will post their reply when I get one. They did not have that caveat when the 470 first came out.
I fail to see what the difference would be between a 300 cu in six and a 302 V8 as far as the carb is concerned. The carb doesn't know how many cylinders there are. It only responds to vacuum, airflow and load.
Answer from Holley why they do not recommend the 470 Truck Avenger for V8 applications:
"A 350 may create too strong of a booster signal with the 470."
That means they've designed the booster venturis taking into account that most I-6 engines have such restrictive intakes and exhausts that they have difficulty in dropping vacuum to very low levels, while a V8 generally does not have this problem and can reach 0"hg or thereabouts easily. This means that not only more fuel may be pulled, but that the fuel (remember this is an emulsified air/fuel mix at that point) may be atomized into much finer droplets. This *may* allow the fuel droplets to actually vaporize, especially in a hot engine on a hot day. When fuel is turned to vapor, it takes up more volume. (Water is similar. When turned to steam it expands 180 times.) This means that the intake charge loses volumetric efficiency, effectively reducing the size of the engine. Not really a big deal for a stock V8, but a big issue for a racing V8.
One big reason for the using more efficient boosters is for better fuel metering at low RPMs, ideal for a lugging I6. But V8s can lug down too. I'm doing quite well with a stock 350 with a Quadrajet and small tube headers. It's almost as good as an I6. Huge difference between the Quadrajet and the 670 Truck Avenger, which would not lug down at all.
So the big question is... will the 470 TA work on a stock small block? Especially one that you want to lug with and isn't run to high RPMs. I'm still of the opinion that it will work. But given Holley's answer it is not ideal for a small block that's not stock, or is used at WOT often. Consider this... Holley does NOT say the 470 is not ideal for a modified I6 or V6. Those installing a 4-bbl intake on an I6 will likely be installing a bigger cam and better exhaust. There goes the arguments for reduced efficiency of the engine. There has to be some overlap with a V8 at that point. That's why I believe a 470 will work on a bone stock small block that's not treated like a hot rod engine. But this is just my opinion.
"A 350 may create too strong of a booster signal with the 470."
That means they've designed the booster venturis taking into account that most I-6 engines have such restrictive intakes and exhausts that they have difficulty in dropping vacuum to very low levels, while a V8 generally does not have this problem and can reach 0"hg or thereabouts easily. This means that not only more fuel may be pulled, but that the fuel (remember this is an emulsified air/fuel mix at that point) may be atomized into much finer droplets. This *may* allow the fuel droplets to actually vaporize, especially in a hot engine on a hot day. When fuel is turned to vapor, it takes up more volume. (Water is similar. When turned to steam it expands 180 times.) This means that the intake charge loses volumetric efficiency, effectively reducing the size of the engine. Not really a big deal for a stock V8, but a big issue for a racing V8.
One big reason for the using more efficient boosters is for better fuel metering at low RPMs, ideal for a lugging I6. But V8s can lug down too. I'm doing quite well with a stock 350 with a Quadrajet and small tube headers. It's almost as good as an I6. Huge difference between the Quadrajet and the 670 Truck Avenger, which would not lug down at all.
So the big question is... will the 470 TA work on a stock small block? Especially one that you want to lug with and isn't run to high RPMs. I'm still of the opinion that it will work. But given Holley's answer it is not ideal for a small block that's not stock, or is used at WOT often. Consider this... Holley does NOT say the 470 is not ideal for a modified I6 or V6. Those installing a 4-bbl intake on an I6 will likely be installing a bigger cam and better exhaust. There goes the arguments for reduced efficiency of the engine. There has to be some overlap with a V8 at that point. That's why I believe a 470 will work on a bone stock small block that's not treated like a hot rod engine. But this is just my opinion.
The 670 says it's ideal for small blocks and stock big blocks? I know I'm late into this conversation, but was poking around the Holley site.
I'm of the opinion that the 670 is not a good carb for a stock 350. It runs way too rich and does not like to be leaned out. But if you have a hot rodded 350, yeah, it'll probably do just fine. One thing it will positively do and that's fire up and run straight out of the box.
