Forums
New posts
Search forums
What's new
New posts
New media
New media comments
Latest activity
Classifieds
Media
New media
New comments
Search media
Log in
Register
What's New?
Search
Search
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Navigation
Install the app
Install
More Options
Advertise with us
Contact Us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
Hobbies & Interests
Gearheads
47 dodge revamping the engine
Search titles only
By:
Reply to Thread
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Message
<blockquote data-quote="swampratt" data-source="post: 2984076" data-attributes="member: 15054"><p>You guys asked for it now.. have a seat this will be a while.</p><p></p><p></p><p>I liked the Variable Venturi that Ford installed on that 351W. It actually worked very well as long as you knew what to do to it.</p><p></p><p>I also like Holley and Q jets I have about 20 carbs worth running all kinds of them in fact I have actually tested my highly Modified 750 #4779 against my tuned Q jet there was less than 10HP between them and that is due to 1 point different AFR readings.</p><p></p><p>I have ran multiple back to back test using the 3 popular carbs the Holley The AFB style and the Qjet and when tuned correctly you do not notice you even swapped carbs.</p><p></p><p>Now Stock VS stock VS stock with only jet changes the Holley 4779 double pumper and 3310 vacuum secondary with straight leg boosters both holleys were always way down on upper rpm power vs a 750 Q jet that has had the secondary air door set to open fully. and the Holleys were also way down on upper rpm power vs the 750 AFB with only jet changes.</p><p></p><p>This was a 7000+ rpm 350 that the carbs were tested on for max performance.</p><p></p><p>Not being one to give up on any carb I began tweaking the Holleys.</p><p>Starting with modifying the airhorn Choke tower.</p><p>Then centering and polishing the boosters as most were off center. Then polishing and slightly enlarging the venturies.</p><p>Finally thinning the throttle shafts and installing smaller head throttle blade screws.</p><p></p><p>Now the 750 cfm could be realized.. If you research actual flow on the Holley750's they do not even break 700 most of the time.</p><p></p><p>Mixture distribution has much more to do with power sometimes than what a carb will flow.</p><p>Anyway I did finally with those mods get the 4779 and 3310 to pull hard upstairs.</p><p>I have a very tweaked 4779 right now that on a square bore intake it makes about 3HP more average through the entire curve than a modded Qjet. But install the Holley onto a spreadbore intake and then the tables got flipped.</p><p></p><p>I did not test with a 1" spacer which could cure some of the mixture distribution issues.</p><p></p><p>Lots of dyno testing.</p><p></p><p>Now the deal with What you noticed Dennis with the AFB vs Holley could stem from the old days when the AFB's you mostly found were smaller than 750.</p><p>I have many of the small AFB carbs .. say 470cfm and some 625 and some 600 edelbrock performer carbs.</p><p>Those small ones really nose over on the big end.</p><p>The 600 will begin to flatten out about 6000 and you can tell it is way down on power at about 5000 rpm compared to the larger carbs. This is on a weak ass 350 of mine that makes max HP at 5700.. but will twist to 7000.</p><p></p><p>It is even more noticeable on the larger cammed stuff.</p><p></p><p>But Why the 750 AFB because I can tune it much quicker than the Holley for getting a baseline to break in this engine.</p><p>I am sure my 4779 and a Q jet will see service on this engine before it is all said and done.</p><p></p><p>Someone here can attest to how well this 750 AFB runs. I loaned it to him to run on his 57 chevy 2 door that beat my 57 chevy 4 door in the ultimate slow car battle. His 2 door 4 speed aluminum head with headers and lumpy cam + loud exhaust. Vs my stock cast iron intake and Qjet 268H cam with iron exhaust manifolds and TH350+ quiet exhaust.</p><p>They said it was the best running driving carburetor they ever had.</p><p></p><p></p><p>[MEDIA=youtube]Mr8c56EsTVc[/MEDIA]</p></blockquote><p></p>
[QUOTE="swampratt, post: 2984076, member: 15054"] You guys asked for it now.. have a seat this will be a while. I liked the Variable Venturi that Ford installed on that 351W. It actually worked very well as long as you knew what to do to it. I also like Holley and Q jets I have about 20 carbs worth running all kinds of them in fact I have actually tested my highly Modified 750 #4779 against my tuned Q jet there was less than 10HP between them and that is due to 1 point different AFR readings. I have ran multiple back to back test using the 3 popular carbs the Holley The AFB style and the Qjet and when tuned correctly you do not notice you even swapped carbs. Now Stock VS stock VS stock with only jet changes the Holley 4779 double pumper and 3310 vacuum secondary with straight leg boosters both holleys were always way down on upper rpm power vs a 750 Q jet that has had the secondary air door set to open fully. and the Holleys were also way down on upper rpm power vs the 750 AFB with only jet changes. This was a 7000+ rpm 350 that the carbs were tested on for max performance. Not being one to give up on any carb I began tweaking the Holleys. Starting with modifying the airhorn Choke tower. Then centering and polishing the boosters as most were off center. Then polishing and slightly enlarging the venturies. Finally thinning the throttle shafts and installing smaller head throttle blade screws. Now the 750 cfm could be realized.. If you research actual flow on the Holley750's they do not even break 700 most of the time. Mixture distribution has much more to do with power sometimes than what a carb will flow. Anyway I did finally with those mods get the 4779 and 3310 to pull hard upstairs. I have a very tweaked 4779 right now that on a square bore intake it makes about 3HP more average through the entire curve than a modded Qjet. But install the Holley onto a spreadbore intake and then the tables got flipped. I did not test with a 1" spacer which could cure some of the mixture distribution issues. Lots of dyno testing. Now the deal with What you noticed Dennis with the AFB vs Holley could stem from the old days when the AFB's you mostly found were smaller than 750. I have many of the small AFB carbs .. say 470cfm and some 625 and some 600 edelbrock performer carbs. Those small ones really nose over on the big end. The 600 will begin to flatten out about 6000 and you can tell it is way down on power at about 5000 rpm compared to the larger carbs. This is on a weak ass 350 of mine that makes max HP at 5700.. but will twist to 7000. It is even more noticeable on the larger cammed stuff. But Why the 750 AFB because I can tune it much quicker than the Holley for getting a baseline to break in this engine. I am sure my 4779 and a Q jet will see service on this engine before it is all said and done. Someone here can attest to how well this 750 AFB runs. I loaned it to him to run on his 57 chevy 2 door that beat my 57 chevy 4 door in the ultimate slow car battle. His 2 door 4 speed aluminum head with headers and lumpy cam + loud exhaust. Vs my stock cast iron intake and Qjet 268H cam with iron exhaust manifolds and TH350+ quiet exhaust. They said it was the best running driving carburetor they ever had. [MEDIA=youtube]Mr8c56EsTVc[/MEDIA] [/QUOTE]
Insert Quotes…
Verification
Post Reply
Forums
Hobbies & Interests
Gearheads
47 dodge revamping the engine
Search titles only
By:
Top
Bottom