Edelbrock AVS Bog/ Carb Recommendations
10-30-2014, 08:49 PM
#1
Pro
Thread Starter
Edelbrock AVS Bog/ Carb Recommendations
Here is what I have:
1979 Corvette
Original block bored .030 over.
Keith Black Aluminum pistons
AFR heads
Edelbrock performer RPM intake (square bore)
Edelbrock cam (I'm assuming the performer RPM cam, but am not 100% sure)
4-speed transmission (almost all of the threads I've looked at gave recommendations specifically for automatics).
3.36 rear, but the wide ratio transmission puts first gear right where it should be for performance. I'm debating putting in a 3.70 with a close ratio transmission, but this should be a non-issue at this point.
Edelbrock AVS 650CFM carb.
I've had the car for 2.5 years, with the engine rebuilt right after I bought it. It has always had a bog when the secondaries were opened. Any gear, and RPM, when the pedal goes down to where you can feel the secondaries open, it falls flat on its face for a split second before roaring to life. I asked my engine builder months later why I had the bog, and he said it was because I had the Performer (AFB) carb. During the build of a 455 for my Buick, I made sure that if he couldn't use the Q-Jet, that he use the Thunder (AVS) carb. I then realized that he did actually use an AVS carb on my Vette. I've started trying to adjust the bog out of the secondaries, but if things go how I think they're going to, I'm not opposed to changing the carb.
The car is primarily my daily driver, but it has seen the drag strip and was recently autocrossed (the bog killed me out there), and I'd like to continue to autocross this car.
Getting those last 5 horsepower at WOT isn't as important as a nice crisp, no hesitation response. When I floor it, I don't want it to argue with me; I want it to GO. However, running well without constant adjustments is a necessity. I haven't had to tune the Edelbrock carb in 2.5 years; the bog is my only complaint, but it's keeping me from enjoying my engine that cost a significant amount of money. I've also seen that the resident carb expert (Lars) doesn't really like them.
Because it's a square bore intake (instead of the combination square and spread bore that Edelbrock now offers), I'm looking at Holley. I have a few in mind that I'm looking at, but I figured I'd as for recommendations before I show my hand. Thanks in advance!
1979 Corvette
Original block bored .030 over.
Keith Black Aluminum pistons
AFR heads
Edelbrock performer RPM intake (square bore)
Edelbrock cam (I'm assuming the performer RPM cam, but am not 100% sure)
4-speed transmission (almost all of the threads I've looked at gave recommendations specifically for automatics).
3.36 rear, but the wide ratio transmission puts first gear right where it should be for performance. I'm debating putting in a 3.70 with a close ratio transmission, but this should be a non-issue at this point.
Edelbrock AVS 650CFM carb.
I've had the car for 2.5 years, with the engine rebuilt right after I bought it. It has always had a bog when the secondaries were opened. Any gear, and RPM, when the pedal goes down to where you can feel the secondaries open, it falls flat on its face for a split second before roaring to life. I asked my engine builder months later why I had the bog, and he said it was because I had the Performer (AFB) carb. During the build of a 455 for my Buick, I made sure that if he couldn't use the Q-Jet, that he use the Thunder (AVS) carb. I then realized that he did actually use an AVS carb on my Vette. I've started trying to adjust the bog out of the secondaries, but if things go how I think they're going to, I'm not opposed to changing the carb.
The car is primarily my daily driver, but it has seen the drag strip and was recently autocrossed (the bog killed me out there), and I'd like to continue to autocross this car.
Getting those last 5 horsepower at WOT isn't as important as a nice crisp, no hesitation response. When I floor it, I don't want it to argue with me; I want it to GO. However, running well without constant adjustments is a necessity. I haven't had to tune the Edelbrock carb in 2.5 years; the bog is my only complaint, but it's keeping me from enjoying my engine that cost a significant amount of money. I've also seen that the resident carb expert (Lars) doesn't really like them.
Because it's a square bore intake (instead of the combination square and spread bore that Edelbrock now offers), I'm looking at Holley. I have a few in mind that I'm looking at, but I figured I'd as for recommendations before I show my hand. Thanks in advance!
10-30-2014, 10:10 PM
#2
Here is what I have:
1979 Corvette
Original block bored .030 over.
Keith Black Aluminum pistons
AFR heads
Edelbrock performer RPM intake (square bore)
Edelbrock cam (I'm assuming the performer RPM cam, but am not 100% sure)
4-speed transmission (almost all of the threads I've looked at gave recommendations specifically for automatics).
3.36 rear, but the wide ratio transmission puts first gear right where it should be for performance. I'm debating putting in a 3.70 with a close ratio transmission, but this should be a non-issue at this point.
Edelbrock AVS 650CFM carb.
I've had the car for 2.5 years, with the engine rebuilt right after I bought it. It has always had a bog when the secondaries were opened. Any gear, and RPM, when the pedal goes down to where you can feel the secondaries open, it falls flat on its face for a split second before roaring to life. I asked my engine builder months later why I had the bog, and he said it was because I had the Performer (AFB) carb. During the build of a 455 for my Buick, I made sure that if he couldn't use the Q-Jet, that he use the Thunder (AVS) carb. I then realized that he did actually use an AVS carb on my Vette. I've started trying to adjust the bog out of the secondaries, but if things go how I think they're going to, I'm not opposed to changing the carb.
The car is primarily my daily driver, but it has seen the drag strip and was recently autocrossed (the bog killed me out there), and I'd like to continue to autocross this car.
Getting those last 5 horsepower at WOT isn't as important as a nice crisp, no hesitation response. When I floor it, I don't want it to argue with me; I want it to GO. However, running well without constant adjustments is a necessity. I haven't had to tune the Edelbrock carb in 2.5 years; the bog is my only complaint, but it's keeping me from enjoying my engine that cost a significant amount of money. I've also seen that the resident carb expert (Lars) doesn't really like them.
Because it's a square bore intake (instead of the combination square and spread bore that Edelbrock now offers), I'm looking at Holley. I have a few in mind that I'm looking at, but I figured I'd as for recommendations before I show my hand. Thanks in advance!
1979 Corvette
Original block bored .030 over.
Keith Black Aluminum pistons
AFR heads
Edelbrock performer RPM intake (square bore)
Edelbrock cam (I'm assuming the performer RPM cam, but am not 100% sure)
4-speed transmission (almost all of the threads I've looked at gave recommendations specifically for automatics).
3.36 rear, but the wide ratio transmission puts first gear right where it should be for performance. I'm debating putting in a 3.70 with a close ratio transmission, but this should be a non-issue at this point.
Edelbrock AVS 650CFM carb.
I've had the car for 2.5 years, with the engine rebuilt right after I bought it. It has always had a bog when the secondaries were opened. Any gear, and RPM, when the pedal goes down to where you can feel the secondaries open, it falls flat on its face for a split second before roaring to life. I asked my engine builder months later why I had the bog, and he said it was because I had the Performer (AFB) carb. During the build of a 455 for my Buick, I made sure that if he couldn't use the Q-Jet, that he use the Thunder (AVS) carb. I then realized that he did actually use an AVS carb on my Vette. I've started trying to adjust the bog out of the secondaries, but if things go how I think they're going to, I'm not opposed to changing the carb.
The car is primarily my daily driver, but it has seen the drag strip and was recently autocrossed (the bog killed me out there), and I'd like to continue to autocross this car.
Getting those last 5 horsepower at WOT isn't as important as a nice crisp, no hesitation response. When I floor it, I don't want it to argue with me; I want it to GO. However, running well without constant adjustments is a necessity. I haven't had to tune the Edelbrock carb in 2.5 years; the bog is my only complaint, but it's keeping me from enjoying my engine that cost a significant amount of money. I've also seen that the resident carb expert (Lars) doesn't really like them.
Because it's a square bore intake (instead of the combination square and spread bore that Edelbrock now offers), I'm looking at Holley. I have a few in mind that I'm looking at, but I figured I'd as for recommendations before I show my hand. Thanks in advance!
10-30-2014, 11:01 PM
#3
Pro
Thread Starter
That's what I've been adjusting when I said I've been trying to adjust it. So far, I've gone from the recommended 1.5 turns all the way to pegging the air flap closed. I have yet to find a setting that eliminates the bog. I'm going to try to narrow it down soon, but I'm not sure it will be possible. I've also messed with the accelerator pump to no avail.
10-30-2014, 11:44 PM
#4
If your ignition timing is set correctly and the advance functions properly your flat spot is on the primary side.
Change the step up springs and / or go 2 to 4 sizes richer on jet / rod combo.
Change the step up springs and / or go 2 to 4 sizes richer on jet / rod combo.
10-31-2014, 12:23 AM
#5
Pro
Thread Starter
Timing and advance were all set up when the engine was built and installed in my car. I can instantly push the throttle down to just before where the secondaries open, and I get instant throttle response. However, if the pedal gets to the point where the secondaries open, the car hesitates. I can feel the change in resistance in the pedal and hear the difference in engine sound when the secondaries open. This is also a pretty common issue with these carbs.