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Unread 08-06-2012, 11:38 AM   #31
Matt1981CJ7
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Dada,

Good work. Your centrifugal curve is much improved.

I'm at 6000' elevation and run my initial at 11. It runs fine at 12, but I like to be on the safe side.

So, when do we get to see a video of the "Golden Tune".

Matt

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Unread 08-06-2012, 11:50 AM   #32
Dadamsnv
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Quote:
Originally Posted by Matt1981CJ7 View Post
Dada,

Good work. Your centrifugal curve is much improved.

I'm at 6000' elevation and run my initial at 11. It runs fine at 12, but I like to be on the safe side.

So, when do we get to see a video of the "Golden Tune".

Matt
Thanks Matt

Right now my tune is more like a bronze tune (Olympic joke)
I have a few more things (dial in main jets, experiment with vac advance) to get done before I will consider it golden.

Also, I have an embarassing header leak I need to take care of before I post a video.

I'm glad to know you also advance your base tuning for elevation! That validates the research I did this morning
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Unread 08-06-2012, 06:20 PM   #33
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I can feel that the ol 304 could use a bit more carb at about 2700 RPM. She tends to have a very predictable climb in speed right up until that point, then she climbs speed linearly and a bit slower. I can certainly get by with the holley 350 without a single problem, and I bet I can get pretty good mileage out of it, but a little bit bigger carb might give me everything I want (power, economy, 4x4 prowess).

I've been eye balling the Holley truck avenger 470. Holley states that the 470 is for six cylinder motors, but there is no reason a small v8 like the 304 couldn't manage one just fine. Have any of you guys used this carb, or do any of you have any ideas/opinions on this carb?? It has everything done to it already that I would do to my 2300 (350 CFM 2bbl) for wheeling. I feel 470 CFM should be perfect for it because it has the performer intake, tube headers, and will eventually have a torquey low end cam. The Summit CFM calculator puts a 304 race motor with a 5000 RPM max at 484 CFM (not that mine will be all raced out with high RPM goodies). I feel like anything larger will be past the point of diminishing returns.

Thoughts? Ideas?
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Unread 08-06-2012, 06:42 PM   #34
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Don't forget that the Holley 2 barrel and 4 barrel carbs are rated at different depressions.

If you were to compare them both at the 1.5 inch depression that 4 barrels are rated at for a more apples to apples kind of deal, it'd be more like a 271 carb vs. a 470 carb. I think the 470 is probably about right for a 304 grunt.


Shawn
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Unread 08-06-2012, 06:56 PM   #35
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Love the thread. One question. Why is your distributer vacuum advance pointed straight at the radiator. All the 304's I've seen point to the driver side radiator and head light, unless your firing order has been altered...?

Sorry if this is stupid question but...just curious.

Again, love the thread.

SC
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Unread 08-06-2012, 07:50 PM   #36
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Quote:
Originally Posted by swatson454
Don't forget that the Holley 2 barrel and 4 barrel carbs are rated at different depressions.

If you were to compare them both at the 1.5 inch depression that 4 barrels are rated at for a more apples to apples kind of deal, it'd be more like a 271 carb vs. a 470 carb. I think the 470 is probably about right for a 304 grunt.

Shawn
Ha ha. I feel dumb, I have no idea what that means, what is depression??
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Unread 08-06-2012, 07:57 PM   #37
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Quote:
Originally Posted by ASteve
Love the thread. One question. Why is your distributer vacuum advance pointed straight at the radiator. All the 304's I've seen point to the driver side radiator and head light, unless your firing order has been altered...?

Sorry if this is stupid question but...just curious.

Again, love the thread.

SC
Thanks man

I'm just as curious as you, I don't know why it's like that. Haha
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Unread 08-06-2012, 08:52 PM   #38
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Big guy,

I don't have any personal experience with the Truck Avenger 470. But I read a post where it was the traditional rant about "fuel injection being god" and "engines can't run on carburetors" yada, yada, yada. This guy was commenting on the 470 and he was a jeep cross country racer. That is all he did for a living. He used one for four years (?) on his vehicle through all his jeep went through and never had a problem. It did what he needed it to do. From his reply, I would trust them. But I have no personal experience with the 470.

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Unread 08-06-2012, 09:16 PM   #39
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Quote:
Originally Posted by Dadamsnv View Post
Ha ha. I feel dumb, I have no idea what that means, what is depression??
My bad.

To rate a carb's airflow, they have to pull a vacuum through it and measure it. They also have to pull the same vacuum (depression) through different carbs to know which one flows more in a fair and accurate way.

4 barrels are usually flowed at a 1.5 inch pressure drop (same thing as vacuum or depression, just sounds more engineerier ) while most 2 barrels are flowed at a 2.5 inch pressure drop.

For example, they'll hook a 4 barrel up to a flow bench and turn up the juice till a fancy sensor or a simple manometer tells the operator that a 1.5 inch pressure drop between atmosphere and the vacuum under the carb has been achieved. Then the machine tells how much air is flowing through the carb at that depression.

2 barrels have always had the flow bench cranked up to a 2.5 inch drop. You have to mathematically convert the readings if you want an apples to apples comparison between a 2 barrel and a 4 barrel.

Clear as mud?
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Unread 08-06-2012, 11:17 PM   #40
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Quote:
Originally Posted by 1SASjeepster
Big guy,

I don't have any personal experience with the Truck Avenger 470. But I read a post where it was the traditional rant about "fuel injection being god" and "engines can't run on carburetors" yada, yada, yada. This guy was commenting on the 470 and he was a jeep cross country racer. That is all he did for a living. He used one for four years (?) on his vehicle through all his jeep went through and never had a problem. It did what he needed it to do. From his reply, I would trust them. But I have no personal experience with the 470.

Take care,
Thanks

I'm of the opinion that while FI is great for wheeling, a carb can be made to function just fine if you know what you are doing, and personally I'm a big carb fan.
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Unread 08-06-2012, 11:23 PM   #41
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Quote:
Originally Posted by swatson454

My bad.

To rate a carb's airflow, they have to pull a vacuum through it and measure it. They also have to pull the same vacuum (depression) through different carbs to know which one flows more in a fair and accurate way.

4 barrels are usually flowed at a 1.5 inch pressure drop (same thing as vacuum or depression, just sounds more engineerier ) while most 2 barrels are flowed at a 2.5 inch pressure drop.

For example, they'll hook a 4 barrel up to a flow bench and turn up the juice till a fancy sensor or a simple manometer tells the operator that a 1.5 inch pressure drop between atmosphere and the vacuum under the carb has been achieved. Then the machine tells how much air is flowing through the carb at that depression.

2 barrels have always had the flow bench cranked up to a 2.5 inch drop. You have to mathematically convert the readings if you want an apples to apples comparison between a 2 barrel and a 4 barrel.

Clear as mud?
Makes perfect sense

I like things that sound engineerier. After all, I just graduated from UNR (university of Nevada Reno) with a BS in mechanical engineering. I would love to be involved in the development of these systems, but I'm a few years behind I suppose

The only thing that doesn't make sense is why they would take the CFMs of 2 and 4 bbl carbs at different depressions.

Thanks for the info man!
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Unread 08-07-2012, 07:11 AM   #42
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i have the TA 470 on my jeep and i am happy so far.
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Unread 08-07-2012, 07:41 AM   #43
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I run a 470 on a Chevy 305 trail Jeep. I also run a Quadrajet on a 360. I prefer the Q-jet. The reason being, the Q-jet doesn't flood out as soon. The 470 is good to 45, the Q-jet will go over 50.

On your calculations for carb size, Hollys website say to multiply your final CFM by 80%. This is because the engine is roughly 80% efficient.

Bill
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Unread 08-07-2012, 07:46 AM   #44
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Who?.....what?....did someone say "Q-jet on a 360"?

It's getting close, buddy. The butterflies are fluttering.

Sorry, carry on.

Matt
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Unread 08-07-2012, 09:37 AM   #45
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Quote:
Originally Posted by lsukevinc View Post
i have the TA 470 on my jeep and i am happy so far.
Glad to hear it!

I've hear some good and some bad stuff, but the bad stuff always seems to be operator error.
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