Carb choice.......which one for the set up I have??
09-04-2009, 02:51 PM
#11
Join Date: Oct 2008
Location: oregon
Posts: 1
there is a formula for finding the right cfm. (c.i.d x max rpm) / 3456 = ideal cfm thats what your motor would need at 100% efficiency. but most street motors only run at about 80%.... so assuming your 289 turns 6500 rpm you would only need 543 cfm at 100% efficiency. so a 600 would be more than you would need by more than 50 cfm before you even factor in the 20% loss in efficiency.
i would personally go with a holley. they usually get a bad wrap because they dont come out of the box tuned and the average joe dont know how to tune them. but if you know how they will out perform a edelbrock any day in my opinion. also mechanical secondaries would be ideal in a lighter car like yours. not to mention its alot more basic. and as im sure most would agree, in this case less is more
i would personally go with a holley. they usually get a bad wrap because they dont come out of the box tuned and the average joe dont know how to tune them. but if you know how they will out perform a edelbrock any day in my opinion. also mechanical secondaries would be ideal in a lighter car like yours. not to mention its alot more basic. and as im sure most would agree, in this case less is more
09-04-2009, 02:57 PM
#12
3rd Gear Member
Join Date: Jul 2009
Location: Smyrna, TN
Posts: 678
I fiddled with 2 600cfm holleys I had for years and rebuilt but came across a near new used Demon Jr. 625cc electric choke for 1/3$. This carb. has worked flawlessly for me and has site glasses built in. I just rebuilt my 289 stroked to 333 with similar add ons like you have and will be using this carb when the motor starts back up. BG is conservative with their CFM rating so I would add at least 25cc to the size for comparison. Inlet bowls are super smooth and this is the best 'looking' carb. I've ever used, I like to leave the air cleaner off at shows.
I may upgrade to a dual inlet road demon if this one turns out to be a little 'small' when tuned but plan to stick with BG.
Jon
I may upgrade to a dual inlet road demon if this one turns out to be a little 'small' when tuned but plan to stick with BG.
Jon
Last edited by Jonk67; 09-04-2009 at 03:00 PM.
09-04-2009, 05:41 PM
#13
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
It's amazing how many carburetor myths there are out there.
Holley's don't have design flaws that make them leak. They've gotten a bad rap over the years not because they have problems, but because the USERS of Holleys have problems. They've leaked because of neanderthal operators that over tighten everything and damage the gaskets. Nearly every time it's either the wrong carburetor for the application, improperly tuned, or the person using it manhandles stuff they shouldn't. If I over tightened my intake and damaged the gasket and got a vacuum leak, that's not the gaskets fault, so why do we blame the carburetor when the same thing happens? They leak because they're mishandled, or people try to get away with using the cheapest gaskets they can find.
When I mess with my QFT 650, EVERY time I reassemble it I check every gasket to make sure it's in proper condition, take care in how I handle them, and evenly TORQUE my float bowls. How many other people in here do that with their carburetor? I've never had a single leak and the carburetor operates flawlessly across a wide range of altitude and weather conditions. Most people just slap them back together and hand tighten them.
As far as CFM ratings, Demons aren't under rated, they're properly rated. They wet flow them with boosters in place flowing fuel to account for the displacement of airflow from the fuel cone as the booster sprays. As a result they're accurately rated to what cfm they flow in real world operation. Other manufacturers do that as well.
Holley's don't have design flaws that make them leak. They've gotten a bad rap over the years not because they have problems, but because the USERS of Holleys have problems. They've leaked because of neanderthal operators that over tighten everything and damage the gaskets. Nearly every time it's either the wrong carburetor for the application, improperly tuned, or the person using it manhandles stuff they shouldn't. If I over tightened my intake and damaged the gasket and got a vacuum leak, that's not the gaskets fault, so why do we blame the carburetor when the same thing happens? They leak because they're mishandled, or people try to get away with using the cheapest gaskets they can find.
When I mess with my QFT 650, EVERY time I reassemble it I check every gasket to make sure it's in proper condition, take care in how I handle them, and evenly TORQUE my float bowls. How many other people in here do that with their carburetor? I've never had a single leak and the carburetor operates flawlessly across a wide range of altitude and weather conditions. Most people just slap them back together and hand tighten them.
As far as CFM ratings, Demons aren't under rated, they're properly rated. They wet flow them with boosters in place flowing fuel to account for the displacement of airflow from the fuel cone as the booster sprays. As a result they're accurately rated to what cfm they flow in real world operation. Other manufacturers do that as well.
09-05-2009, 02:31 AM
#14
5th Gear Member
Join Date: Dec 2008
Location: Texas
Posts: 4,462
It's amazing how many carburetor myths there are out there.
Holley's don't have design flaws that make them leak. They've gotten a bad rap over the years not because they have problems, but because the USERS of Holleys have problems. They've leaked because of neanderthal operators that over tighten everything and damage the gaskets. Nearly every time it's either the wrong carburetor for the application, improperly tuned, or the person using it manhandles stuff they shouldn't. If I over tightened my intake and damaged the gasket and got a vacuum leak, that's not the gaskets fault, so why do we blame the carburetor when the same thing happens? They leak because they're mishandled, or people try to get away with using the cheapest gaskets they can find.
When I mess with my QFT 650, EVERY time I reassemble it I check every gasket to make sure it's in proper condition, take care in how I handle them, and evenly TORQUE my float bowls. How many other people in here do that with their carburetor? I've never had a single leak and the carburetor operates flawlessly across a wide range of altitude and weather conditions. Most people just slap them back together and hand tighten them.
As far as CFM ratings, Demons aren't under rated, they're properly rated. They wet flow them with boosters in place flowing fuel to account for the displacement of airflow from the fuel cone as the booster sprays. As a result they're accurately rated to what cfm they flow in real world operation. Other manufacturers do that as well.
Holley's don't have design flaws that make them leak. They've gotten a bad rap over the years not because they have problems, but because the USERS of Holleys have problems. They've leaked because of neanderthal operators that over tighten everything and damage the gaskets. Nearly every time it's either the wrong carburetor for the application, improperly tuned, or the person using it manhandles stuff they shouldn't. If I over tightened my intake and damaged the gasket and got a vacuum leak, that's not the gaskets fault, so why do we blame the carburetor when the same thing happens? They leak because they're mishandled, or people try to get away with using the cheapest gaskets they can find.
When I mess with my QFT 650, EVERY time I reassemble it I check every gasket to make sure it's in proper condition, take care in how I handle them, and evenly TORQUE my float bowls. How many other people in here do that with their carburetor? I've never had a single leak and the carburetor operates flawlessly across a wide range of altitude and weather conditions. Most people just slap them back together and hand tighten them.
As far as CFM ratings, Demons aren't under rated, they're properly rated. They wet flow them with boosters in place flowing fuel to account for the displacement of airflow from the fuel cone as the booster sprays. As a result they're accurately rated to what cfm they flow in real world operation. Other manufacturers do that as well.
My Dad had a 85 F150 that came factory with the 5.8 HO. It had Holley 4 bbl from the factory. That truck did not like the winter time very much and we are in Texas. It took a while to warm up before it would run good. However, the rest of the time that truck would move. So, Holley obviously did something right.
The Edelbrock as well as Carter are less tempermental to summer winter etc.
It just seem to me that they are more finicky than Edelbrock or Carter AFB etc. If someone is building a street car / cruiser and wants it to be reliable and easy to work with then I recommend agains Holley. Keep in mind that I am not saying that Holley is bad. I just don't care for it.
If I was building a strip only car or 500 hp hot rod it would probably have a different carb, but for my car the Edelbrock is a good fit.
Anyway, I don't know why people have to argue or put people down for their opinions. Thats just what they are. If someones personal experience with something was bad then it was bad. I like to hear everyones opinion.
Personally, I think Holley does have problems and the power valve is a peice of junk. I can't even remember how many of them blew on that F150 and my friends vehicles. Nothing is perfect though right.
Last edited by tx65coupe; 09-05-2009 at 02:41 AM.
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