Does anyone have an easy way to set the two mixture screws? I read the directions that come with the carb, but I'm still sort of confused. I'm sure its real simple, once you know what your doing...Thanks
I wouldn't trust their tuning instructions. That is why I posted my question originally.
The instructions tell you to turn the mixture needles rich (ccw) until the rpm's quit rising as you turn it, then restting the curb idle speed. Next, it says something about turning it a little lean to get a 40 rpm drop.
I adjusted mine per the instructions, and it was running so rich that it would bog on acceleration.
Out of the box, it idled and ran better than it does now. I wish I had left it alone. I would still like to know the factory setting. I e-mailed Edelbrock, but I did not get a reply. In the end, I adjusted it like a Holley, which is about 1 1/2 turns out from bottom. It runs OK, but the idle is rougher than with the Holley. I changed to the Edelbrock because I couldn't get the Holley to lean out. I picked up 0.3 mpg, same power, but worse idle. I think it may be a little on the lean side now.
Off idle bogging is usually caused by an inadequate (volume wise) accelerator pump, or extremely lean idle. The idle screws actually need to be slightly rich to help the transition from idle to cruise. The best way to set idle is to use a vac. guage and play for a while.
I'm going to try contacting Edelbrock as well. I also had my carb running a little better, before I messed with it. The directions that they provide are really confusing. Hopefully someone from Edelbrock tech, can explain it in plain english. If I get a clear explanation on how to set it, I will post it up for anyone who is in the same boat. I was really excited when I got the latest issue of CAR CRAFT last week. They have an article on tuning carbs. On the cover there is a picture of some dude tweaking a Edelbrock. Unfortunatly the article centers on Holley. Talk about a let down...
These carbs do not adjust like a Holley so forget about Holley adjustment stuff. The Edelbrock needs a bit leaner idle mixture setting to run right. First, completely warm up the motor and make sure your timing is right and you have no vacuum leaks. Adjust this thing with the air cleaner installed.
Start with one idle mixture screw. Turn it out a little richer until idle vacuum just starts to drop off then turn it in leaner until vacuum goes up and you get the best idle smoothness. Reset your idle speed screw. Go to the other mixture screw and do the same thing then reset your idle speed again. Go back to the first screw and trim it in leaner just until the rpms start to drop. Reset the idle speed screw again to the proper idle rpms. Do the same for the other screw. Reset idle speed and you are done. Keep track of your turns and they should be the same amount of turns out from the bottom on both screws.
I basically do the same thing as Hottarod, except for without the vacuum gauge. I adjust one screw richer (counter clockwise) until you get the fastest idle out of it, then do the same with the other screw. Then adjust one screw leaner (clockwise) until the RPM just barely starts to drop, then do the same with the other screw. Then adjust idle speed. And last, I usually count how many turns out each screw is (by screwing it back in until it bottoms out) just to make sure both adjustments are pretty close to the same place.
I had the same problem with it falling on it's face off-idle, and I cured it by richening the idle mixture slightly and setting the accelerator pump on maximum (the hole closest to the pivot on the pump arm). From what I've seen the accelerator pump on these carbs is inadequate, and most rigs run best with the pump on the maximum setting.
'86 Bronco fullsize, 460cid, E4OD w/ Baumannator TCS, 4" Rancho lift, 2" body lift, 35x12.5 BFG AT KOs, 4.56 gears, Auburn posi in the 9" rear, Digital instruments, 600watt Pioneer sound system
<font size=-1>[ This Message was edited by: Motorhead on 6/3/02 3:32am ]</font>