Thread: Edelbrock / Carter carb mods

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Hey there, anyone with knowledge about modifying the Edelbrock / Carter style carbs would be appreciated.

What I have done to my Edelbrock Performer 600 carb (electric choke model):
I basicly spent a several hours with a die grinder to open up the primaries quite a bit and smooth out casting flaws. I did not change the butterfly openings at all but I did knife-edge the butterflies and file down the butterfly shafts. I stopped grinding away material well before the small openings for the idle circuit.

MY problem:
Now the carb flows much more air but in doing so I believe I have redused the venturi booster signal considerably and the carb is not suplying enough fuel for the fire. I have come to this conclusion because the bigger jets I keep putting into the carb the better but it is still all wrong. I went from .092 on the primaries (before the mods) to drilling out a pair of duplicate jets with an 1/8 (.125) drill bit just to get the car down the road and it is still way too lean. I also have an A/F ratio meter installed in the exhaust so I can monitor the mixture.

Anyone with suggestions on how to correct this situation with the venturi booster or has some insight to another possible issue I have created for myself would be greatly appretiated.

Did you grind the venturi's to a larger diameter?
If you did there's the reason for the overly lean condition you describe.
You no longer have the pressure differential required to pull fuel.

How do you know you flow more air - without having the carb on a flow bench?

A 125 jet is pretty big.

You're aware that part of the lean/rich ratio changes are accomplished with a change of rods are you not?

Float levels change lean/rich ratio's as well.

Yes I am aware that changing rods changes the mixture. The reason I got this carb is beacause it is so easy to change the rods. I am running the smallest rods on the cruise setting I have already .062.

I have not altered the venturis aside from removing a little flash on the outside to smooth it out and smoothed out the dogleg where the venturi attaches to the side of the carb.

I have not tinkered with float level yet, but the bowls were always full of fuel when I took the carb apart to change jets.

I agree that .125 is rediculously huge for a jet. The largest size Edelbrock sells is .119. This is why I have come to the assumption that I have screwed up the pressure differential and there is not enough booster signal to draw fuel through the jets. Any help as to how too increase booster signal or install different venturis to compensate would be helpful.

Thanks for your response C9x

It sounds like you have a fairly good vacuum leak.
Places to check are the obvious, intake gaskets, carb gaskets as well as making sure unused bibs on the carb proper are sealed off. Especially so the small ones at the front of the carb. (Passenger side bib is ported vacuum and drivers side is full-time vacuum.)

Do you have another carb you could try?
That would duplicate the overly lean condition if it's not a carb problem.

You may want to take at look at Edelbrock's online carb manual.
Go here: http://www.edelbrock.com/automotive/...ubleshoot.html

Backtrack from there to access other areas of the manual.