AVS2 issues
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5th Wheeling
Joined: Mar 2024
Posts: 39
Likes: 3
AVS2 issues
Hello, I yet again have another issue with this 67’ 390FE but i recently installed a edelbrock performer 4BBL intake and a avs2 650cfm and it starts up fine and revs fine in neutral but when I do a wide open throttle it just bogs its way to stalling in neutral also. When I drive it it does not want to accelerate only once it drove fine and accelerated fine and I changed the metering rod springs from red to yellow, messed with the 3 holes for fuel shot and zero difference. If anyone has any suggestions I would appreciate to hear them all thank you 🙏
Lead Driver
Joined: Oct 2018
Posts: 7,892
Likes: 2,370
The best cure for all the problems of a Edelbrock AFB is a Holley 4160.
But if you're not ready to throw it away yet check your fuel delivery. it sounds like once your fuel bowl runs out its starving. filters, pump, suction screen in the tank, tank ventilation or the carb could be the cause.
But if you're not ready to throw it away yet check your fuel delivery. it sounds like once your fuel bowl runs out its starving. filters, pump, suction screen in the tank, tank ventilation or the carb could be the cause.
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5th Wheeling
Joined: Mar 2024
Posts: 39
Likes: 3
The best cure for all the problems of a Edelbrock AFB is a Holley 4160.
But if you're not ready to throw it away yet check your fuel delivery. it sounds like once your fuel bowl runs out its starving. filters, pump, suction screen in the tank, tank ventilation or the carb could be the cause.
But if you're not ready to throw it away yet check your fuel delivery. it sounds like once your fuel bowl runs out its starving. filters, pump, suction screen in the tank, tank ventilation or the carb could be the cause.
i actually have a brand new Holley 4160 and it was actually worse from my experience it wouldn’t want to stay idling let alone run and I have messed with the Holley to get it to stay alive but zero difference, even the engine starts ticking bad with the Holley.
Lead Driver
Joined: Oct 2018
Posts: 7,892
Likes: 2,370
If it won't run right with a new Holley it's not the carb. and if it does the same thing with another carb that confirms it. once you figure out the problem go back to the Holley it's far better than an AFB.
So now that you know it's not the carb it's time for a process of elimination. the obvious first considerations are a vacuum leak and timing. at an idle slowly cover the air horn with a rag and see what happens. it should die. if it does then loosen the distributor and at an idle move it around both ways and see if you can make it run good. don't worry about a light at this point you have to make it run first.
Fuel starvation is still a possibility , not knowing what you have or the condition makes it impossible to guess.
So now that you know it's not the carb it's time for a process of elimination. the obvious first considerations are a vacuum leak and timing. at an idle slowly cover the air horn with a rag and see what happens. it should die. if it does then loosen the distributor and at an idle move it around both ways and see if you can make it run good. don't worry about a light at this point you have to make it run first.
Fuel starvation is still a possibility , not knowing what you have or the condition makes it impossible to guess.
Tuned
Joined: Dec 2012
Posts: 335
Likes: 180
I’ve had good success with an 800cfm AVS2 on my 428; but it was running good with EFI previously, and ran well with an older 750 Edelbrock that was on my 429.
Read back through Edelbrocks instructions, if you haven’t already. Pull the carb apart and verify there’s no debris, or binding, and that the choke and secondary air door are set up properly. Run your air bleed screws all the way in and back out 2-1/2 turns to re-set.
As 440 already said: Verify no vac leaks, which could also be a cracked rubber plug in the carb base. Verify fuel pressure, and supply. Verify timing, and advance. Verify spark plugs and wires (check gap, and look for cracks).
i would strongly suggest installing a vacuum gauge and AFR gauge as well; it’s made tuning so much easier. I’ll never try to tune without one again.
Also, to help you fully understand function and tuning, look up Uncle Tony’s Garage on YouTube. He’s got a good video series on Edelbrocks, and Holleys.
Read back through Edelbrocks instructions, if you haven’t already. Pull the carb apart and verify there’s no debris, or binding, and that the choke and secondary air door are set up properly. Run your air bleed screws all the way in and back out 2-1/2 turns to re-set.
As 440 already said: Verify no vac leaks, which could also be a cracked rubber plug in the carb base. Verify fuel pressure, and supply. Verify timing, and advance. Verify spark plugs and wires (check gap, and look for cracks).
i would strongly suggest installing a vacuum gauge and AFR gauge as well; it’s made tuning so much easier. I’ll never try to tune without one again.
Also, to help you fully understand function and tuning, look up Uncle Tony’s Garage on YouTube. He’s got a good video series on Edelbrocks, and Holleys.
Tuned
Joined: Dec 2012
Posts: 335
Likes: 180
Spaced out; when you have the top of the carb off, check the floats. They should hang 7/16” down, basically so the top of the float is parallel with the carb body. Also wouldn’t hurt to check the needles. Just follow Edelbrocks directions.
Mine brand new out of the box were slightly off; seemed like one got jostled during shipping and the other was probably put in at “good enough for a Friday.”
Mine brand new out of the box were slightly off; seemed like one got jostled during shipping and the other was probably put in at “good enough for a Friday.”
Its Comin Right for us!
Joined: Feb 2005
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From: GA
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Hotshot
Joined: Feb 2004
Posts: 10,832
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From: The Shenandoah Valley
A leaking accelerator pump piston (on a plunger) that doesn't completely seal to the wall of the well it is in will not always deliver a full shot. Also if the linkage up top is not right it delivers less fuel with each stroke, if any. In neutral just revving, there is much less load on the engine, it will rev quicker with a lower accelerator pump delivery but under load, like road work, it'll stumble, even stall as all air at WOT with no added fuel doesn't burn.
Another possible cause is a secondary air valve that opens too quick.
If the carb is a used one, etc .... could be a bad worn or cracked accelerator pump piston, the new ones are compatible with newer fuels, the old ones weren't so tollerant.
Another possible cause is a secondary air valve that opens too quick.
If the carb is a used one, etc .... could be a bad worn or cracked accelerator pump piston, the new ones are compatible with newer fuels, the old ones weren't so tollerant.
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