Anyone know how to increase the CFM on Edelbrock Carbs?

[lewtot184]

1000cfm, not a chance. i don't think they'll flow 800 ootb, maybe 760-780. i think if you pick up 100+cfm from the mods i suggested you need to through an extra $20 in the plate sunday morning. several years ago one of the mopar mags did a flow test on a 440avs. the 440avs has nearly the same total venturii area as the 800 and all they got out of it was 715cfm. there are tests you can perform when your at the track. try to rig up a vacuum gauge and see how much vacuum the engine is pulling at high rpm. if it's 1"hg or more the carbs are really working, if it's .5"hg or lower i'd look for power someplace else. i also put some notes on yellowbullet if interested.

 

[SUPERSTOCKRACER]

1000cfm, not a chance. i don't think they'll flow 800 ootb, maybe 760-780. i think if you pick up 100+cfm from the mods i suggested you need to through an extra $20 in the plate sunday morning. several years ago one of the mopar mags did a flow test on a 440avs. the 440avs has nearly the same total venturii area as the 800 and all they got out of it was 715cfm. there are tests you can perform when your at the track. try to rig up a vacuum gauge and see how much vacuum the engine is pulling at high rpm. if it's 1"hg or more the carbs are really working, if it's .5"hg or lower i'd look for power someplace else. i also put some notes on yellowbullet if interested.

Thanks I built a whole new motor with much more head flow, CI to make more power with the same intake and heads and it netted me identical mph and ET. So I know the carbs are holding me back big time. Thus the reason for this thread.

 

[lewtot184]

maybe not just the carbs. i'd take a good look at head intake port flow and intake manifold flow.

 

[SUPERSTOCKRACER]

maybe not just the carbs. i'd take a good look at head intake port flow and intake manifold flow.

MODERN CYLINDER HEAD cnc'd my heads and netted me [email protected] lift. Once I get the carb issue worked out the intake is going to MCH for some serious port work. I already had a talk with him but said to try working on the carbs too just to see.

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here's the setup,

 

[splicer]

Just a thought SSR......If your hood scoop was sealed up to the carbs via a sheet metal and foam pan , you would get some ram effect....

Picked up 1 to 1.5 tenths on mine...

Splicer

 

[SUPERSTOCKRACER]

Just a thought SSR......If your hood scoop was sealed up to the carbs via a sheet metal and foam pan , you would get some ram effect....

Picked up 1 to 1.5 tenths on mine...

Splicer

I understand completely but I wanted to do back to back tests with what I had been running all year long with same carbs to run in true NSS form. Results were shocking to say the least.

 

[splicer]

I very much understand what you're saying...

Put Max Wedge heads and intake on mine earlier this year and had the same result you experienced....car ran exactly the same numbers that it ran before the upgrade....

My bottleneck turned out to be the camshaft....went to bigger roller and it came alive....then found the fuel filter was holding it back....and on and on and on....lol

Splicer

 

[SUPERSTOCKRACER]

I very much understand what you're saying...

Put Max Wedge heads and intake on mine earlier this year and had the same result you experienced....car ran exactly the same numbers that it ran before the upgrade....

My bottleneck turned out to be the camshaft....went to bigger roller and it came alive....then found the fuel filter was holding it back....and on and on and on....lol

Splicer

I can't say that was my case because I went from a .800 lift cam to a .840 cam
heads flowed 429 @.900 to [email protected] lift Went from 588 cubes to 604 ci and netted the same thing and I took off 185 lbs. off the nose to boot.

 

[cdr]

have you made a pass without the hood scoop,the carbs look very close to the scoop ??

 

[SUPERSTOCKRACER]

have you made a pass without the hood scoop,the carbs look very close to the scoop ??

YES, with same hood scoop different motors. Been running it like this for years. My other scoop was even closer with no issues.

 

[rumblefish360]

Sorry I can not be of any real help to expanding the carb CFM. The 800's just have a straight bore. Increasing the size would help but I do not know how far you can bore it. I have a AFB & AVS 800 to look at and tinker with.

Expanding the bore size could be done but to what length, I do not know. Internally there could be an issue with fuel paths. Then there is the butterfly issue.

 

[lewtot184]

making the bore bigger is a no-go. enlarging the venturii is doable.

 

[SUPERSTOCKRACER]

Dale Cubic was modifying these carbs but no longer is due to the poor castings that they are made of. Dale told me out of 8 carbs he modified, he had to throw in the trash 5 due to blowing through the material.
I did see he was able to make the top air bleeds adjustable but not sure how he did that.

 

[passin gas]

Big Turbo!

 

[lewtot184]

if you can find a small enough and short enough brass set screw it can be done. the only thing that would concern me is the vertical tube on top of the primary cluster the sticks thru the top of the carb. i believe this tube to be the high speed air bleed and does it have to be above the top of the carb, in the air flow, to work?

 

[snakeoil24]

Trash them! get 2 950 Holleys or a pair of Dominators and be done with it.

 

[SUPERSTOCKRACER]

Trash them! get 2 950 Holleys or a pair of Dominators and be done with it.

you mean like these!!
I'm trying to avoid using these and get my 8 second passes in the summer months with no issues.

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if you can find a small enough and short enough brass set screw it can be done. the only thing that would concern me is the vertical tube on top of the primary cluster the sticks thru the top of the carb. i believe this tube to be the high speed air bleed and does it have to be above the top of the carb, in the air flow, to work?

How deep does that high speed tube go down?
What would the set screw do for performance gains? What about the dominator style air bleeds that screw in?

 

[lewtot184]

the high speed, maybe i should say main metering, air bleed is the small tube that sticks up out the the top of the primary cluster. it also pokes thru the top of the carb. small bras set screws can be drilled to any size you want. basically thats what holley emullsion bleeds and idle jets are. the holleys are 6-32's but i think that may be too large in size to drill and tap on the small cluster. 4-40's may be better. i'm not sure that playing with air bleeds will get much, unless the fuel curve is all screwed up. with 600 cubes have you ever done the math for proper plenum volume? is the LSA on the camshaft optimized for the power band you need? pretty technical questions but i'd chase them.

 

[SUPERSTOCKRACER]

the high speed, maybe i should say main metering, air bleed is the small tube that sticks up out the the top of the primary cluster. it also pokes thru the top of the carb. small bras set screws can be drilled to any size you want. basically thats what holley emullsion bleeds and idle jets are. the holleys are 6-32's but i think that may be too large in size to drill and tap on the small cluster. 4-40's may be better. i'm not sure that playing with air bleeds will get much, unless the fuel curve is all screwed up. with 600 cubes have you ever done the math for proper plenum volume? is the LSA on the camshaft optimized for the power band you need? pretty technical questions but i'd chase them.

Cam was spec'd by Tim Banning @FHO. He has proven combo that's why I went with his cam.
LSA should be spot on. never did the math for plenum volume

 

[Budnicks]

is there something in the Assoc. rules of certain events you want to run,
that you have to run the Weber/Carter Clone/Edelbrock carbs ? for some reason or other...

why beat your head against the wall, reinvent the wheel {carb in this case} if you don't have too,
just run the other set-up, if it's they're the proper ones & size for your combo...
save the Eddy's for another of your cars or Bobtile's...he he ha ha


Unless there's some rule why you can't... than your screwed

my $0.02 cents

good luck