Edelbrock 500 secondaries question

[Guest Anonymous]

I'm running an Edelbrock/Weber/Carter/whatever 500 carby. On the secondaries, there's a weighted set of butterflies above the main butterflies, which I presume are to help the secondaries cut in more smoothly. Has anyone tried removing the top set of butterflies, in an attempt to get better (but perhaps more "vicious") throttle response? Are there any web references for tuning this carby?

[Guest Anonymous]

Not a good idea as I've heard the carb will run very poorly if you do that. That air door you mentioned is the reason the edelbrock/AFB is such a good carb, makes a big difference to mileage and driveability.

[Modern Motorsports Ltd]

zedskid, the whole edelbrock tuning manual is typically online at their web. And quite a commendable piece of work IMO. Each circuit/function is isolated rather easily to make tuning the various circuits quite straightforward. For different 'tip in' on a standard edelbrock/carter (if not timing related) you can

1)change accel. pump linkage slot

2) change the primary to secondary transition springs (initiates tip in at less or more vaccuum depending on pair swapped in, takes less than a minute to do any of above mods FWIW.

 

That upper butterfly controls vaccuum response/hence the weights.....airflow thru a carb is typically the last possible problem for V8 owners when tuning carbs.

 

I'd recommend getting the tuning kit for your carb and read their full manual. Document your changes so it's easy to follow in hindsite.

 

I ran my $$$$ motor on a free carb for few years early on and have always regretted it....I waited too long to get a carb dialed in etc.

 

good luck

[Guest Anonymous]

Thanks for the tips, guys. You're right, Ross, the Edelbrock web page is excellent. I'm reading thru it now.

 

BTW, the carby is working OK, I just wondered if removing the upper butterflies would make things better - from your replies and reading the Edelbrock stuff, obviously not. As Arnie said when he hit the Predator over the head with the tree branch, "Bhaad Ideea".

[GrayZee]

The primaries have a accelerator pump to give a shot (squirt) of gas into the the carb to richen the mixture momentarily when the throttle is opened. The reason for this is because when the throttle is opened air rushes in very quickly (faster than the flow of fuel can begin) Without this "shot" of fuel the car would bog out on acceleration. 4 barrel carbs that have secondary butterfly valves serve essentially the same pupose, they delay the flow of air. You see, when the secondaries open there is a vacuum build up under the butterfly valve and when the vacuum is high enough then they will be forced to open. By that time the fuel will have began to flow... Giving you a smooth transition. The butterfly valves may look like a restriction but they are there for a purpose. Other 4barrel carbs may not have butterfly valves but then they would have vacuum controlled secondary instead Or a accelerator pump for the secondaries. (double pumper) Hope this clears things up (clear as mud)