difference in eddy carbs - simple questions

[Stegs]

I was doing some research last night on carbs, specifically eddy carbs

Right now i have a new eddy performer 600 cfm on my 440. The carb runs fine, and i had no issues, but since i got my motor redone i feel that the car wants more air. I swapped out my intake during the rebuild and went with a eddy performer. (nice difference)


Well i was on the edelbrock website last night, found the carb i have and it said "tuned for max fuel economy"....as I scrolled down i came across the 1411 (750 cfm) carb

This one said tuned for maximum performance. My questions are

1. am I missing out on performance with a carb that is designed for fuel economy? would i get better performance with a 750 over the 600?
2. Could i take my 600 off, and put a 750 on and everything will work the same as the 600 (fuel line location, throttle linkage, vac ports, etc)


I know when i was searching for a carb, alot of guys suggested a proform carb....but I cant really complain about the eddy carbs so far....(I just feel the car wants more than 600 cfm)

whats your guys thoughts?

[HPP]

Economy vs performance tune typically means they install rods and jets to produce a leaner mixture. If you did any tuning of your carb since install, you have altered this original tune. Since they  set these up to fit the maximum number of variables on the maximum number of cars, it probably is close but not optimum for your set up. The same can be said of their performance tuned carbs.

Any carb will need tweaking to be optimized for the combo. For some carbs this entails a lot of changes, for some its a few changes, but unless you are buying a custom carb from a builder that  quizes you on your engine specs, they all require tuning.

You can tune your 600 to work better, but if you need more airflow, only a step up in cfm will add the air needed.

[Stegs]

Economy vs performance tune typically means they install rods and jets to produce a leaner mixture. If you did any tuning of your carb since install, you have altered this original tune. Since they  set these up to fit the maximum number of variables on the maximum number of cars, it probably is close but not optimum for your set up. The same can be said of their performance tuned carbs.

Any carb will need tweaking to be optimized for the combo. For some carbs this entails a lot of changes, for some its a few changes, but unless you are buying a custom carb from a builder that  quizes you on your engine specs, they all require tuning.

You can tune your 600 to work better, but if you need more airflow, only a step up in cfm will add the air needed.

right, i know i can tune the carb to better work for me...which i will do anyway....but i feel after the rebuild, the car wants more air flow.....

The 600 cfm on the old motor worked better than it does now on the fresh motor.

maybe i should look into a 750

[c00nhunterjoe]

What exactly was done to the engine?

[Hard Charger]

would think a 440 would need a 750cfm

Thunder series AVS from Eddy has good tune-ability

[c00nhunterjoe]

If its a bone stock 440, put a 650 on it. If its very tame ie, headers "rv cam" performer i take, then put a 750 on it. If it has a respectable cam, intake, and exhaust, then go for the 850. If shes any wilder then that, we are gonna need details.

[WindJammer]

If its a bone stock 440, put a 650 on it. If its very tame ie, headers "rv cam" performer i take, then put a 750 on it. If it has a respectable cam, intake, and exhaust, then go for the 850. If shes any wilder then that, we are gonna need details.

Love it man. That sounds like something out of a movie. Well said! 

[BSB67]

The 600 cfm on the old motor worked better than it does now on the fresh motor.

What do you mean by this?  In what way did the old motor ran better?

[Challenger340]

1.) What Camshaft was installed in the Engine ?

The CAM determines how FAR the Valves get opened, and how LONG they are open, which together determine how much BREATHING the Engine requires, related to Carburetor sizing.

2.) What Pistons were installed in the Engine ?

Because the Intake Valve does not close until well after the Piston is already on it's way back up the Cylinder from Bottom Dead Center,(Bleeding off available Compression), it is important to know how much Compression Pressure is available initially(piston), as it relates to throttle response in Carburetor sizing.

[Challenger340]

Well i was on the edelbrock website last night, found the carb i have and it said "tuned for max fuel economy"....as I scrolled down i came across the 1411 (750 cfm) carb

This one said tuned for maximum performance. My questions are

1. am I missing out on performance with a carb that is designed for fuel economy? would i get better performance with a 750 over the 600?
No, because Eddy Jets ALL their carbs to stay within a targeted stocchiometric Air/Fuel range anyway, no matter 600 or 750. The only question really is whether the Engine can make use of the extra 150 cfm, which is determined by CAMSHAFT and COMPRESSION(Pistons)

2. Could i take my 600 off, and put a 750 on and everything will work the same as the 600 (fuel line location, throttle linkage, vac ports, etc)
Yes, most everything else should be pretty much same-same, nothing that can't be overcome.


I know when i was searching for a carb, alot of guys suggested a proform carb....but I cant really complain about the eddy carbs so far....(I just feel the car wants more than 600 cfm)
Proforms are great, but again here, without knowing the CAMSHAFT and PISTONS used in the Engine, you are very probably just wasting your money.

whats your guys thoughts?

My thoughts are this.
If you went ahead when building your Engine with your "builders" reccomendation for those so-called "High" Pistons, even after all the warnings you were given on this site about them, and then also used a Composition style Head Gasket, and then with with an unknown Camshaft, that if you are now "after the fact" looking for more PERFORMANCE with a Carburetor ?, your chances may be very limited to success ? with "Bolt-ons", Carb or otherwise ?, because the fundamental mistakes were already "built-in" internal of the Engine ?

[Stegs]

update

I tuned the carb a little bit this weekend, car seemed to run a touch better. I will do more when i have some more time


The old motor was a tired old girl, bad rings, 8 bad exhaust valves, 2 bad intake valves. The cam was worn down from the previous owner not running zinc.


Now its basically a factory rebuild. Stock cam, stock pistons, stock rods, stock bottom end. The heads got a port and polish with all new exhaust and 2 intake valves

I replaced the factory intake with a eddy performer...


The 600 seemed fine on the old motor because it was tired......now being all fresh with good compression, im feeling that it would like more air and fuel.

Like i said, the motor is a basic stock rebuild, nothing crazy at all...but it seems like there is a bunch of [power there that the 600 wont let happen.


Ill adjust the carb some more, see if i cant tune this one better for me.

I guess if i save some cash and go with a 750, there really is no down side to it right?

[fy469rtse]

No down side,
I like the eddys, 750 size, will help with the air and performance gains
600 more suited to a B motor,
but it will be rich out of the box, purchase one of the coresponding needle and rod kist,
The tuning book supplied with the new carb makes it easy,

[firefighter3931]

Hey Scott,

Before you go spending any cash on a bigger carb make sure to check and see where your timing is set. 

It should have ~ 16* at idle and 36-38* total, all in by 2500 rpm or so. 


Ron

[c00nhunterjoe]

For that engine, a 650-750 will do just fine. Out of the box, a 750 probably wont even require a jet change.

[Challenger340]

update

Now its basically a factory rebuild. Stock cam, stock pistons, stock rods, stock bottom end. The heads got a port and polish with all new exhaust and 2 intake valves

Like i said, the motor is a basic stock rebuild, nothing crazy at all...but it seems like there is a bunch of [power there that the 600 wont let happen.

I guess if i save some cash and go with a 750, there really is no down side to it right?

No downside whatsoever going to the 750 Carb, other than the aforementioned cash outlay.

The factory "stock" specs, "stock" cam, 1972 to 1978 230hp engines used an 800 cfm Thermoquad Carburetor from factory, so no reason yours can't handle the 750 cfm Eddy Carb being a very similar engine build.






   

[Stegs]

Hey Scott,

Before you go spending any cash on a bigger carb make sure to check and see where your timing is set. 

It should have ~ 16* at idle and 36-38* total, all in by 2500 rpm or so. 


Ron

I will, once i get a few other odd jobs done on the car, i want to take it away and have it dyno tuned. Then i know im set. I just have a few other little things i have to take car of first


Great info guys...I will try to work with this carb for now...tune it as best i can while i finish up other things


Maybe i will invest in a new 750 eddy later down the road!

[myk]

Maybe I'll just send you mine, as I've learned to hate it over the years.  When I was 'carb shopping back in the day I heard complaints about the Performer having limited tuning capability (unlike a Holley), and a lot of other users cited an off idle bog they couldn't fix; from the lack of tunability maybe?  But it looked so good in the Summit catalog I bought it anyway.  In any case, I'll be looking at another brand in a while.  

Oh about the Performer intake, did you get the regular Performer or the Performer RPM?  I ask because it's been said that the regular Performer intake is not much better than the stock piece, and possibly even worse flowing.  I know I lost low end torque when I went with the Performer intake and tossed out the stock intake...

[Stegs]

Maybe I'll just send you mine, as I've learned to hate it over the years.  When I was 'carb shopping back in the day I heard complaints about the Performer having limited tuning capability (unlike a Holley), and a lot of other users cited an off idle bog they couldn't fix; from the lack of tunability maybe?  But it looked so good in the Summit catalog I bought it anyway.  In any case, I'll be looking at another brand in a while.  

Oh about the Performer intake, did you get the regular Performer or the Performer RPM?  I ask because it's been said that the regular Performer intake is not much better than the stock piece, and possibly even worse flowing.  I know I lost low end torque when I went with the Performer intake and tossed out the stock intake...

I did just the performer, and i must say the motor runs fantastic. Its a fresh motor so its real hard to say how much better this one is over the factory iron...But i got no complaints here.


I went with the performer b/c i was told the performer RPM would not fit under the hood with the air cleaner im using (edelbrock cleaner with a napa gold filter)

No complaints about the intake tho..bolted right up. I read people talk about it and say it was worse than the original....but i have a hard time believing edelbrock would spend time researching and developing that intake if it was worse than late 60s mopar intakes.

Like i said, hard to say with a fresh motor....but it runs strong...throttle responds is great and it pulls very very strong from idle to 3500ish rpm (still breaking in new motor)

[69wannabe]

The 600 eddy carbs that I have used have been mostly good carbs but of the several 750 eddy carbs I have tried none of them were worth using or even trying to use. If you are going up to a 750 consider a holley 3310 or the summit 750 carb's that are sold by summit racing. These would be the most reasonable to try as far as money is concerned. I have seen several hollley 750 vacuum secondary carb's on mild built 383's and 440's that work pretty good.....

[Stegs]

The 600 eddy carbs that I have used have been mostly good carbs but of the several 750 eddy carbs I have tried none of them were worth using or even trying to use. If you are going up to a 750 consider a holley 3310 or the summit 750 carb's that are sold by summit racing. These would be the most reasonable to try as far as money is concerned. I have seen several hollley 750 vacuum secondary carb's on mild built 383's and 440's that work pretty good.....

Id go with a Holley, but i hear they are a pain in the *** to tune, they dont hold a tune very good, and they are a pain to install on our cars because they are designed to work with a carter/eddy style


if i switch to holley, do i have to redo all my throttle linkage?

Looking at holley, the have dominator, avenger, street avenger.....what part number would you guys suggest for me? 750 with electric choke?

And whats the benfits of a vacuum secondary/mechanical secondary?

[Ghoste]

I don't think they are a pain to install at all, there were a large number of our cars sold with Holley carbs as well so I dont know where someone would say they were designed for Carters.  I'd disagree somewhat with the pain to tune part as well.  MY opinion would be more that the Holley offers so many more tuning parameters that it can be a bit intimidating.

[HPP]

IMO, the Carterbrocks are easy to tune and can be dialed in to be very crisp with decent mileage on a street engine. Its very nice that fine tuning the Ebrock can be done with draining gas every time a change is needed. The Holley or Holley based (Proform, etc) may make more absolute power but do take more effort to tune and are messier to get there.

I've heard a lot of bad opinions on ebrock 750s. They seem to be hit or miss. I've used several and never had problems with them, but I've never had problems with MP leaf springs either and they also have a bad rap. I guess I'm just lucky.

There is also the new Demon version of the top cover style Carter carb that may be a decent option. they tune like the Ebrock but have a number of new features in them.

[Challenger340]

 
Without knowing the Cam specs, there is no way to guesstimate whether a bigger Carb will help or hinder ?  
Just trial and error.

Any chance you could borrow a Carb from a friend to "try" it first before spending ? Just a thought, we used to swap stuff around all the time.

If it helps any, here are the "stock" 440-4BBL Cam Specs for comparison.

                               260/268
Intake Lift: .434"     Exhaust Lift: 430"

Int open: 18* BTDC      Int Close: 62* ABDC                                      

Exh Open: 68* BBDC     Exh Close: 20* ATDC
               
                              LSA: 113*

                            Overlap: 38*

The above "stock" Cam with 38* overlap is all done by 4800 rpm, no way around it.
Porting and Intake Manifold cannot change LIFT and DURATION. It just "helps" within the Cams program(4800)
and,
A Carburetor swap could potentially make little if any difference for the money spent ? if the Engine can't utilize the extra cfm anyways ?

A 440 Engine @ 4800 rpm Cam "capability"..... really can't use much, if any more cfm than the 600 ?
More like 450 to 520 cfm @ .85 Volumetric Efficiency, which is where THAT cam is !

Here is a link to a fairly accurate engine cfm requirement calculator to illustrate what you may encounter ?
http://www.gtsparkplugs.com/CarbCFMCalc.html

Just a suggestion....
If it runs well ?
You may wish to consider making sure the Timing Curve(Initial & Total Timing) is correct like Ron suggested, leave the 600 cfm Carb on it ? call it a day and go enjoy it ?

trivia;
The only reason the factory installed the 800 thermobogs on the smogger engines was to compensate for the heavily silenced Air Cleaners and high underhood installation temps(thinner air), then run on 2 very small efficient front barrels most of the time for efficiency with high Air/Fuel velocity, then when required, try to "cheat V.E.", on the low ambient underhood air pressure by providing massive "holes" on the secondary's for power. It did work, but it was only marginal on stock(non hp) Cams vrs AFB/AVS systems.

[Stegs]

Without knowing the Cam specs, there is no way to guesstimate whether a bigger Carb will help or hinder ?  
Just trial and error.

Any chance you could borrow a Carb from a friend to "try" it first before spending ? Just a thought, we used to swap stuff around all the time.

If it helps any, here are the "stock" 440-4BBL Cam Specs for comparison.

                               260/268
Intake Lift: .434"     Exhaust Lift: 430"

Int open: 18* BTDC      Int Close: 62* ABDC                                      

Exh Open: 68* BBDC     Exh Close: 20* ATDC
               
                              LSA: 113*

                            Overlap: 38*

The above "stock" Cam with 38* overlap is all done by 4800 rpm, no way around it.
Porting and Intake Manifold cannot change LIFT and DURATION. It just "helps" within the Cams program(4800)
and,
A Carburetor swap could potentially make little if any difference for the money spent ? if the Engine can't utilize the extra cfm anyways ?

A 440 Engine @ 4800 rpm Cam "capability"..... really can't use much, if any more cfm than the 600 ?
More like 450 to 520 cfm @ .85 Volumetric Efficiency, which is where THAT cam is !

Here is a link to a fairly accurate engine cfm requirement calculator to illustrate what you may encounter ?
http://www.gtsparkplugs.com/CarbCFMCalc.html

Just a suggestion....
If it runs well ?
You may wish to consider making sure the Timing Curve(Initial & Total Timing) is correct like Ron suggested, leave the 600 cfm Carb on it ? call it a day and go enjoy it ?

trivia;
The only reason the factory installed the 800 thermobogs on the smogger engines was to compensate for the heavily silenced Air Cleaners and high underhood installation temps(thinner air), then run on 2 very small efficient front barrels most of the time for efficiency with high Air/Fuel velocity, then when required, try to "cheat V.E.", on the low ambient underhood air pressure by providing massive "holes" on the secondary's for power. It did work, but it was only marginal on stock(non hp) Cams vrs AFB/AVS systems.

yes im having the timing looked at for now and adjusted properly according to rons post above

I will leave the 600 cfm eddy for now...maybe this fall upgrade to a holley....but the eddy 600 does run good..just feels like the motor wants more.(that could be timing too)

[firefighter3931]

Hey Scott,

Before you go spending any cash on a bigger carb make sure to check and see where your timing is set. 

It should have ~ 16* at idle and 36-38* total, all in by 2500 rpm or so. 


Ron

I will, once i get a few other odd jobs done on the car, i want to take it away and have it dyno tuned. Then i know im set. I just have a few other little things i have to take car of first


Great info guys...I will try to work with this carb for now...tune it as best i can while i finish up other things


Maybe i will invest in a new 750 eddy later down the road!

You must nail down the timing curve before anything else. There's no point trying to tune fuel delivery if the timing curve is out of whack. 

First thing to do is get the timing light on it and verify where things are. 



Ron