Should I go Holley?

[CAJ1971]

I’m having issues with my engine bogging down. It runs ok, but It seems like there is just something holding it back and it’s like the other 2 barrels are not opening up. Here is what i have. 71 short step, 350, 20 over, flat tops, vortec heads, headman long tube headers, Lunati cam with .465 lift and .224/.224 @.050, 700r4 stage II , 373 gears. And the carb is Edlebrock 650 AVS 2. I have made adjustments to the back plate of the carb but nothing seems to help. Would you guys think a Holley double pumper would be a good answer?
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[CAJ1971]

I’m having issues with my engine bogging down. It runs ok, but It seems like there is just something holding it back and it’s like the other 2 barrels are not opening up. Here is what i have. 71 short step, 350, 20 over, flat tops, vortec heads, headman long tube headers, Lunati cam with .465 lift and .224/.224 @.050, 700r4 stage II , 373 gears. And the carb is Edlebrock 650 AVS 2. I have made adjustments to the back plate of the carb but nothing seems to help. Would you guys think a Holley double pumper would be a good answer?
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[Mike C]

You should buy a book on the Edelbrock carb IMO and learn how it really works and put a kit in yours, including a new accelerator pump, and sort that out.

[CAJ1971]

Originally Posted by Mike C

You should buy a book on the Edelbrock carb IMO and learn how it really works and put a kit in yours, including a new accelerator pump, and sort that out.

Well I would but everything is new already and doesn’t need a kit. The truck has about 5000 miles on restoration.
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[HO455]

Trading one new carburetor for another one is not likely to solve the problems you mentioned. There are at least a half a dozen things that could be causing your been poor performance. Many of them won't cost anywhere near as much as a new carburetor. And you may have more than one thing out of adjustment.

What kind of ignition do you have?
What is your timing set at? initial? Total? How much mechanical advance does your distributor have? At what rpm is the mechanical advance all in? How much vacuum advance are you getting?
How was the cam installed straight up? Advanced?
Was your timing tab zeroed to top dead center when the engine was assembled?
Are your spark plug wires installed correctly?
How were the valves adjusted?
Any of these things could be wrong and limit performance and changing carburetors doesn't cause them to magically get corrected.

Have you looked down the carburetor bore while someone floors the gas (engine off) to verify that the secondaries are actually fully open?
Before changing carburetors you should hook up an Air/Fuel ratio meter to find out exactly what is happening.

[CAJ1971]

Originally Posted by HO455

Trading one new carburetor for another one is not likely to solve the problems you mentioned. There are at least a half a dozen things that could be causing your been poor performance. Many of them won't cost anywhere near as much as a new carburetor. And you may have more than one thing out of adjustment.

What kind of ignition do you have?
What is your timing set at? initial? Total? How much mechanical advance does your distributor have? At what rpm is the mechanical advance all in? How much vacuum advance are you getting?
How was the cam installed straight up? Advanced?
Was your timing tab zeroed to top dead center when the engine was assembled?
Are your spark plug wires installed correctly?
How were the valves adjusted?
Any of these things could be wrong and limit performance and changing carburetors doesn't cause them to magically get corrected.

Have you looked down the carburetor bore while someone floors the gas (engine off) to verify that the secondaries are actually fully open?
Before changing carburetors you should hook up an Air/Fuel ratio meter to find out exactly what is happening.

Everything you have mentioned has been checked and is all where it needs to be. Yes I have looked down the bore of the carb with full throttle but they do not open like that. It is my understanding that the AVS secondaries open up with vacuum, not mechanical. That is why I was thinking of going to Holley double pumper mechanical. That way I know they are going to open. I have heard of other guys having the same issues and they went to the Holley set up.

[fdbdw]

The AVS2 is a great carb , Edelbrocks are easy to dial in once you understand them. First thing to do is set your floats and make sure you are running the right fuel pressure. The floats are rarely set correctly out of the box. Tuning is useless if those two things are not right to begin with.

[OregonNed]

Originally Posted by fdbdw

The AVS2 is a great carb , Edelbrocks are easy to dial in once you understand them. First thing to do is set your floats and make sure you are running the right fuel pressure. The floats are rarely set correctly out of the box. Tuning is useless if those two things are not right to begin with.

Agree there. That solved my issues and was really pretty easy to do.

[firedemon]

while I am a huge fan of holley carbs im afraid it wont do you much good unless you can tune it properly . tuning is much more than carb like H0455 says . I would get a book for your carb and a book for power tuning . I find the more I learn about tuning and carbs the more I realize I need to learn

[firedemon]

your cam dosent seem so radical that you would have low vacume . what kind of vacume are you getting at the base of the carb . could have a plugged port somewhere inside the carb if your getting good numbers and the secondary's aren't opening

[tim_mc]

I installed an Edelbrock AVS2 1905 650cfm this month...love it...but not at first. I had bogging problems and had to lean mine two steps on power, and one on cruise...and move my vacuum advance from manifold to ported to eliminate a stumble when accelerating from cruise. I also had to tweak the float adjustment. You *must* use a fuel regulator to knock down the pressure to 4-5psi on Edelbrock carbs.

After a week or two of messing with it, I bought the Edelbrock 1948 kit with extra jets and rods - a necessity unless you're lucky with it out of the box or know exactly which rods and jets to get. Rods are about $15 a set, and the kit (~$62) comes with seven sets, including two rod profiles that are new (made for the AVS?), which was a clue to me that I might wind up using either the 1955 or 1956 rods. Edelbrocks are easy to tune and rod changes are done in a minute. The carb adjustment chart is helpful. Mine is currently set up with #16 on the attached calibration chart: .098 main jets and 1955 rods (.067 x .037) and .098 secondary jets, orange/5"Hg step-up springs. If you get the kit, I found it helpful to color the rods with different color sharpies so I didn't need to keep using a magnifying glass to read the stamped numbers.

My manual choke is wired open - no cable...don't need it. I have not messed with the secondary valve adjustment. Starts easily and has awesome throttle response. I think it's still a bit on the rich side, but runs well for now while I'm breaking in the new 350. Brodix IK180 heads, EPS intake, Comp Cams 12-408-8 retro roller (mild) cam, headers. 700R4, 3.08 gears.

I'm pulling around 16"Hg of vacuum on the manifold. 12 degrees BTDC at the crank, and a new AC Delco HEI for 22 degrees of advance for 34 total, plus another 14 from the vacuum advance, so 48 when cruising - give or take since I've advanced my distributor a bit.

I'd suggest temporarily removing the vac advance and capping the source for now.
Make sure your initial and mechanical advance is where it should be. Get the tuning kit and make some changes based on how rich or lean you think it is, and note your changes as you go. I recommend switching the rods with the stock .101 mains, and work your way down since changing the mains require removing the air horn/top. Sorry for throwing a lot of info at you, but hope it helps as issues with a new carb are not fun.
https://edelbrock-instructions-v1.s3...ning-guide.pdf

[fdbdw]

X2 on the A/F ratio gauge, I installed one when I did my exhaust. Takes the guess work out of tuning. I also installed an edelbrock fuel pump, gives the right psi and no need to mess with a fuel pressure regulator.

[weim55]

X10 on staying with the Edelbrock. Holly double pumper would be going backwards for your application as you stated it.

Steve weim55 Colorado

[RichardJ]

OP
>> It is my understanding that the AVS secondaries open up with vacuum, not mechanical.<<

Open your eyeballs. Mechanical secondary linkage is on passenger side of carb. The only thing that will stop the secondary throttle valves from opening is the choke high speed idle linkage if it is not set up properly. If the high speed idle linkage is not OFF, the big spring on the passenger side of the primary throttle shaft will wind up and the linkage will not move to open the secondarys.

HO
>>The Edlebrock 650 AVS 2 has a vacuum controlled secondary air valve/flapper that operates the secondary metering rods.<<

Carter and Edelbrock clones do not have "secondary metering rods". Primary only.
The original Carter AVS carbs had three step metering rods and still, primary only.

>>https://youtu.be/fL-zDjpvrEg<< This video is worthless.

AVS stands for Air Valve Secondary, not Adjustable Valve secondary.
This valve opens with air flow and is adjustable. It does not open with vacuum.

[HO455]

My bad I forgot that Edelbrocks relied on fuel emulsification to manage the secondary air fuel ratios. I've never been a fan of Edelbrocks so I usually replaced them instead of work on them.
The video was to give the OP some background on his carburetor so maybe he would be less inclined to replace a modern carburetor with a 1960's design.

Open your eyeballs. Mechanical secondary linkage is on passenger side of carb. The only thing that will stop the secondary throttle valves from opening is the choke high speed idle linkage if it is not set up properly. If the high speed idle linkage is not OFF, the big spring on the passenger side of the primary throttle shaft will wind up and the linkage will not move to open the secondarys.

So you are saying that an improperly installed throttle cable bracket, or a throttle cable attached to the wrong place on the throttle shaft, or too short of a throttle rod, (67-68) or too much insulation on the firewall, or a damaged kickdown cable won't prevent the secondarys from opening completely?

[RichardJ]

>>So you are saying that an improperly installed throttle cable bracket, or a throttle cable attached to the wrong place on the throttle shaft, or too short of a throttle rod, (67-68) or too much insulation on the firewall, or a damaged kickdown cable won't prevent the secondarys from opening completely? <<

You forgot to mention if his feet were too short and couldn't reach the peddles.

My info about the linkage had to do with him not understanding why the throttle wasn't opening as he thought it should. If he understood that it didn't have vacuum secondary's and understood that they should be opening. Perhaps then he would have investigated if the insulation was too thick or his legs too short.

His choice to switch to a Holley shouldn't be based on what he didn't know about the Edelbrock any more than it shouldn't be based on what YOU don't know about the Edelbrock.

[Killer Bee]

^ appropriate user name

[LockDoc]

-
If things look a little strange it's because I merged his two threads.

CAJ1971: do not start two threads about the same problem. It is against board rules....

LockDoc,
Moderator

[Jcfcamaro]

That would be to much carburetor. Probably need a 600 with vacuum secondary maybe a 750.

[jimijam00]

I would tune it until it's dead nuts on as reflected by eight clean plugs.

[tinman_local2]

What's your timing set at? Ignition timing will really make a difference. Are you sure you don't have any vacuum leaks?

[HO455]

For some reason the OP has 2 threads going on this. See link.

https://67-72chevytrucks.com/vboard/...d.php?t=807106

[HO455]

CAJ1971 I sincerely hope you solve the problem with your truck.
It has become obvious that I don't have the knowledge to help you.
You are new here but I am certain that someone will be able help you and in turn you become a long term participant on the forum.

HO455

[CUDA8U]

Throw the eddy in garbage, get a holley, quick fuel or a proform

I had an eddy on my 500hp 440 and it seemed like it was held back a bit, i put an 850 holley on, followed tuning instructions from a friend. Rejetting etc. I took it for the first drive and blew my cell phone off the dash into the back seat. Unreal difference! The creator of www.cudachallenger uses proform carbs and loves them. He is very knowledgeable about engine building.

[ltdmstr]

Holley 6210 spread bore is a great carb for 350 sbc. You can get a like-new factory rebuild for pretty good price at Jegs or Summit.