Anyone know how to increase the CFM on Edelbrock Carbs?

[lewtot184]

the 50cfm difference between the two is probably correct. the advertised flow numbers are just high. there's about 7/10's of an inch of venturii difference between the two and the 800's larger throttle bores do help even if the venturii area was the same. but, i don't think there is a big power difference between the two. if you take the 50cfm difference and spread that over eight cylinders the gains aren't great. i'm a multi-carb guy who thinks people put too much confidence in a single 4bbl. i've always thought it was silly how folks would buy all kinds of gadgets and gimmicks to gain air flow on their single carb and at the same time totally shun two carbs, which they probably need.

 

[SUPERSTOCKRACER]

the 50cfm difference between the two is probably correct. the advertised flow numbers are just high. there's about 7/10's of an inch of venturii difference between the two and the 800's larger throttle bores do help even if the venturii area was the same. but, i don't think there is a big power difference between the two. if you take the 50cfm difference and spread that over eight cylinders the gains aren't great. i'm a multi-carb guy who thinks people put too much confidence in a single 4bbl. i've always thought it was silly how folks would buy all kinds of gadgets and gimmicks to gain air flow on their single carb and at the same time totally shun two carbs, which they probably need.

What I have found is that when I run a pair of 750 carters on my big motors meaning 588 ci and 604 ci and the metering jets are .119 my A/F goes leaner than when I run my 800 Edelbrocks

 

[lewtot184]

sounds like the 750's are hitting a wall. don't know exactly why but could be the emulsion tubes are restrictive, main air bleeds too large or maybe something in the main well passages blocking flow? with displacement a constant air would have to travel thru the smaller carbs faster making them more responsive to fuel flow; wouldn't you think?

 

[SUPERSTOCKRACER]

sounds like the 750's are hitting a wall. don't know exactly why but could be the emulsion tubes are restrictive, main air bleeds too large or maybe something in the main well passages blocking flow? with displacement a constant air would have to travel thru the smaller carbs faster making them more responsive to fuel flow; wouldn't you think?

Funny thing is that to date those 750's that I am now selling netted me my best ET and mph ever. yes leaner than all my other carbs but they work. High 8's all day long with them.

 

[lewtot184]

Funny thing is that to date those 750's that I am now selling netted me my best ET and mph ever. yes leaner than all my other carbs but they work. High 8's all day long with them.

why not reuse them? sounds like they're making the best torque and horsepower. maybe they're a better match for the intake? on the other hand; find more air in the intake to make the 800's work harder? ain't this fun!

 

[SUPERSTOCKRACER]

why not reuse them? sounds like they're making the best torque and horsepower. maybe they're a better match for the intake? on the other hand; find more air in the intake to make the 800's work harder? ain't this fun!

How would you find more air in the intake? Are you talking porting the intake?

 

[bobtile]

Did you ever try running that setup without a hood? I wonder if those carbs being so close to the hood has anything to do it.

 

[SUPERSTOCKRACER]

Did you ever try running that setup without a hood? I wonder if those carbs being so close to the hood has anything to do it.

No you?

 

[bobtile]

No you?

no

 

[dvw]

Mine has at least 2.5" above the top of the front carb. I've run 113 jets until this fall when the air was very good. I jetted it up to 116 and it gained less than .20 mph. It loses very little in the heat (85 degrees+). Plugs look excellent. 6psi fuel pressure. Sealed hood scoop. Also seems to like the intake hot.
Doug

 

[lewtot184]

How would you find more air in the intake? Are you talking porting the intake?

yes.

 

[SUPERSTOCKRACER]

Mine has at least 2.5" above the top of the front carb. I've run 113 jets until this fall when the air was very good. I jetted it up to 116 and it gained less than .20 mph. It loses very little in the heat (85 degrees+). Plugs look excellent. 6psi fuel pressure. Sealed hood scoop. Also seems to like the intake hot.
Doug

i'd like to see that sealed up hood scoop Doug

- - - Updated - - -

yes.

i'm sending one of my indy hemi tunnel ram intakes to Bob@MCH for him to max port it out but I want to try just the new carbs 1st and get a true comparison.

 

[bobtile]

i'd like to see that sealed up hood scoop Doug

- - - Updated - - -




i'm sending one of my indy hemi tunnel ram intakes to Bob@MCH for him to max port it out but I want to try just the new carbs 1st and get a true comparison.

Send it to me. I have a dremel!
I don't like to brag to guys, but I have a good eye as well as I am a tile man.

 

[SUPERSTOCKRACER]

Send it to me. I have a dremel!
I don't like to brag to guys, but I have a good eye as well as I am a tile man.

I know As I have seen you in action. Your attention to detail is marvelous!

 

[bobtile]

I know As I have seen you in action. Your attention to detail is marvelous!

This is why I don't brag to guys.

 

[Endangered Species]

Take a look at this.

http://www.wallaceracing.com/intakecfm.php

I don't know how accurate the calculator is but if I put in the right numbers you should need anywhere from 1300-1700 CFM for your CI at 105% Volumetric Efficiency and @ 7000 RPM.

 

[SUPERSTOCKRACER]

Take a look at this.

http://www.wallaceracing.com/intakecfm.php

I don't know how accurate the calculator is but if I put in the right numbers you should need anywhere from 1300-1700 CFM for your CI at 105% Volumetric Efficiency and @ 7000 RPM.

that's why I think I don't have enough cfm and I need to try different carbs. Time ill tell if it was worth the price of these carbs.

 

[SUPERSTOCKRACER]

I had a very long conversation with Dale Cubic regarding his modified Edelbrocks and got all the information that I needed.
His modified carbs netted 150 cfm over a stock carb this relates to 300 cfm on a 2 carb setup.
All his customers that put these on their car made significantly more power over the stock Edelbrocks.
3 mph minimum which is great news.
He told me a little trick to straighten out the airflow on Edelbrocks which have horrible turbulence

 

[bobtile]

I had a very long conversation with Dale Cubic regarding his modified Edelbrocks and got all the information that I needed.
His modified carbs netted 150 cfm over a stock carb this relates to 300 cfm on a 2 carb setup.
All his customers that put these on their car made significantly more power over the stock Edelbrocks.
3 mph minimum which is great news.
He told me a little trick to straighten out the airflow on Edelbrocks which have horrible turbulence

I'm waiting to hear the secret.

 

[SUPERSTOCKRACER]

I'm waiting to hear the secret.

Secret handshake 1st!


let's put it this way.
if you run your dual quads, and use this special setup, you will pickup 3 mph.