Holley vs. AVS... opinions...

[ericwevans]

So I know most people will say Holley.  I'd like to get opinions why.  Traditionally I have been an AFB/AVS guy for the reasons that I believed it to be a better street carb (opinion), there are no gaskets below the fuel line, and with the needles I have the ability to tune the cruise and power separately on the primary side of the carb.  For the first time I am considering a Holley carb, but to get the ability to tune the power valve I am looking at a Holley Track Warrior, or a Holley Ultra XP which come with a significant price difference over an AVS, and both come without a choke which I could probably live with if I had to (gets driven daily, so cold startup might get old).  Since my goal is to tinker and make as much HP while retaining as much fuel mileage as possible I am really looking for the tunability.  The added feature of the XP I really like that I believe will improve drivability is the Idle Air Bypass which allows you to maintain optimal closed throttle blade position and adjust the idle with a different mechanism.

So for current pricing comparison...
Thunder AVS: $420
Holley TW: $490
Holley XP: $697

As a final though, since all I am really looking for is power valve adjustability, has anyone tried or successfully just modified a plain jane 4150 metering block for power valve restrictors?  A standard 4150 is only $431.

So should I pay the Holley premium?  And if so, why.  :-)

[Drew Pojedinec]

i've got a holley 4010 if ya want it.

All the benefits of being a Holley with all the leak free issues you mentioned above.

[e philpott]

just installed a Thunder series 650 on a 62 Lincoln 430 , ran great right out of the box , seems to be a good street carb

[My427stang]

I put a 800 Thunder Series on a 390 truck, ran great out of the box.  I like Holleys, but no issues with that carb on the street

[Barry_R]

Consider the amount of effort and development you do to get ports to flow smoothly.

Take a Carter/Edelbrock and hold it up to the light at WOT and look through the bores.
Take a Holley and hold it up to the light at WOT and look through the bores.

One will have clean round passages with minimal flow disruptions.
One will have odd shaped passages and stuff hanging into the flow path.
Both will work and drive.
One will make more power even though the manufacturer's marketing groups will rate them the same.

Please take a moment to drain the fuel prior to the above inspections....   

[ericwevans]

I had considered that, the Holley has a much cleaner flow path.

[RJP]

So I know most people will say Holley.  I'd like to get opinions why.  Traditionally I have been an AFB/AVS guy for the reasons that I believed it to be a better street carb (opinion), there are no gaskets below the fuel line, and with the needles I have the ability to tune the cruise and power separately on the primary side of the carb.  For the first time I am considering a Holley carb, but to get the ability to tune the power valve I am looking at a Holley Track Warrior, or a Holley Ultra XP which come with a significant price difference over an AVS, and both come without a choke which I could probably live with if I had to (gets driven daily, so cold startup might get old).  Since my goal is to tinker and make as much HP while retaining as much fuel mileage as possible I am really looking for the tunability.  The added feature of the XP I really like that I believe will improve drivability is the Idle Air Bypass which allows you to maintain optimal closed throttle blade position and adjust the idle with a different mechanism.

So for current pricing comparison...
Thunder AVS: $420
Holley TW: $490
Holley XP: $697

As a final though, since all I am really looking for is power valve adjustability, has anyone tried or successfully just modified a plain jane 4150 metering block for power valve restrictors?  A standard 4150 is only $431.

So should I pay the Holley premium?  And if so, why.  :-)

What are power valve restrictors? And what modifications to the metering block are needed to accommodate these power valve restrictors?

[ericwevans]

With the upper end Holley's they have metering blocks where the restrictions are adjustable rather than standard machined in restrictions that you can only adjust by drilling out larger which is obviously a permanent modification. 

These adjustments allow you to adjust several things with the power valve being one of them, which allows you to tune the cruise A/F ratio with the main jets and the set the power A/F ratio with the power valve restrictors. 

[My427stang]

What are power valve restrictors? And what modifications to the metering block are needed to accommodate these power valve restrictors?

Keeps your power valves from getting away from you. They can be crazy sometimes 

[ericwevans]

@My427stang    lol

[RJP]

What are power valve restrictors? And what modifications to the metering block are needed to accommodate these power valve restrictors?

Keeps your power valves from getting away from you. They can be crazy sometimes 

Damn...I didn't know there was a fix for that. Slippery 'lil suckers, aren't they?...That could explain all those power valves that turned up missing.