Hey everybody, ths is my first time using any message board. So I'll do my best to be to the point.

I have an 85 d150 225/833od 3.55 rear end
Bored .040
Block shaved .090
Comp cams .440 lift solid cam kit
1.70/1.44 stainless valves
Bench top port and polish
Msd 6AL with blaster 2 coil and Msd 8.5 super conductor wires
Offenhauser intake
Clifford headers
Timing 12* idle 34* all in with paired light (silver) springs

OK, . at should be enough to get started

Here's what's going on. I have been driving this fresh engine for 2 years with a super six 2-barrel setup and it was a dream. It was my daily driver getting between 16-18 mpg in town and on a trip from south Carolina to northern pennsylvania, loaded down with camping equipment, got 22 mpg up and back. Granted it has to have premium fuel.
I had trouble for years with the clutch. 3 clutches later I found the post about putting a ford diagphram clutch in by modifying the flywheel. May I say, that thread was a life saver! I was so close to giving up and getting a 904.
The BBD was working well but was starting to show its age and lacked in power for what I wanted. So I decided to get the offy intake and and edelbrock avs thunder 500cfm carb. I have worked on holleys and edelbrocks before and I believe holleys are the cause of most of my hair loss. Never ever ever ever had a problem with an edelbrock.
So the eddy goes on the off and this is where the problems begin. Now I realize that any 4bbl going on a slant is most likely going to take some fine tuning to get it perfect. But this is ridiculous.
Out of the box it idled like a dream. No complaints so far. Took it out on the first test drive. Not running wide open, just normal take offs and cruising, it stumbles, bucks, hiccups and all other manner of descriptive words in mid range rpm under light load. 1st gear good, 2nd gear OK till about 2k-2.5k then it starts. It refuses to accelerate unless....... you punch it. Wot runs like a scalded dog. If you can get it past that wall, and open it up, it screams from 3.8k-5.5k.
Now I started with the air door and adjusted both ways 1/2 turn at a time till I figured it wasn't doing anything. set it back to factory specs. Pulled #3 plug to check the lean/rich condition. It was perfectly tan with barely any carbon at all. (Strange I thought).

I decided to try a few external adjustments on the eddy. Accelerator pump settings yielded no change. Tried all different metering rod springs. No change. Time to go inside.

Took it apart to check the floats. They were off but only a little bit so I fixed them. Decided to check the jets. Pulled them and laid them on the bench to study them. Noticed something odd. Different sized jets! Neither of which was what it was supposed to be. Put the correct size jets in and noticed the rods where very difficult to get in position. The rods where bowed in the middle and the short end was FAR from a 90* angle. Fixed that issue.

Put it all back together thinking "I got it now!".

Absolutely no change at all.

As I wept uncontrollably, I had a thought. My dad has a avs 650 on his car. Maybe I should try his carb. So I slapped it on and to my surprise it ran quite well! Sure you could tell it was a little too much for the engine, but the main problem was gone! I drove it for a week like that with no issues.

I thought this strange that motor was taking a 650 so well. Pulled #3 plug again and found it was the same as before. Tan with miniscule carbon. That plug shoulg be drowned in fuel!

A friend gave me his inline fuel pressure gauge to check psi with. Found I only had 2-2.5 psi at idle and fell below that when revved up. OK, new fuel pump and 500 put back on. 5.5 psi at idle. Carb returned to factory specs all around. Should be good to go.

The problem is even worse now. Couldn't even make it out of first gear on a normal take off type of acceleration before it happened. And now it won't even run wide open. Plugs are still tan. Still idles good. Can somebody tell me if i just have a junk carb or is there some magical secret timing/air/fuel recipe for getting a 4 bbl going? And why would the 650 work so well and not a 500? I cant possibly have that much motor! Not when it ran good with a BBD on it previously!

Im at the end of my rope! Any insight would be greatly appreciated.

The idle circuit works. That's something, but it sounds like you have junk in the carb causing the main meetering system to starve for fuel. I would check to be sure the passages to the booster venturis are open. It wouldn't be the first time a carb had machining debris left in the passages. Where do you think the Edelbrock reman carbs come from?

_________________
Joshua

I would say that the Carb if new should be returned. Your not the only one that has had problems with the AVS style Edelbrock. Maybe it has some internal passages blocked.Most problems were with the secondary air door when they first came out.The adjuster lock would not stay. I usually try to buy the factory Performer re-mans you find at Summit or Jegs. The Tech at Edelbrock told me that they are line rejects and got to a area that one person goes thru the entire carb even boxing it(Brown Box if you ever bought one) up. That way mistakes are found from the rush of the assembly line.wrong jets, boosters, bent and msimatched metering rods.Etc. Just some food for thought.

Is the accel pump giving a nice hefty squirt? I would assume that is the immediate flat spot when trying to accelerate.

If you got it new I would have returned it at the first signs of internal damage (bent rods, mis-matched jets, etc...) Also yea I have heard alot of complaints about the AVS carbs. The 650 probably just doesnt have any internal issues and is giving a good steady fuel supply across the throttle opening range.

If you dont want to return it, take it apart, soak it in cleaner, blow out all passages, ports, and jets to make sure there are no blockages. Get a matched rod and jet set for the 500 (or something close to what it should have). Get it back together, fill the bowl and re-check for a big pump shot, if you do, put it back on and try driving it again.

Thanks to all who responded. I bought the carb at the summit store in Georgia this past spring. Talk about feeling like a kid in a candy store! I just got around to installing it. So I should have a couple of months left on the 1 yr warranty. I'll try to get edelbrock to exchange this for another 500. Its always fun dealing with any company's warranty department.

In the meantime, how should I clear the passages? I'm assuming using compressed air around 20-30psi? Where do I need to shoot it into? Squirters? Jets? Venturis? Or just disassemble it and find every hole possible? Any place I should avoid?

Summit is pretty good on warranty issues, but it might be too late now, since you opened the carb and replaced parts.

I know what you mean about that store. Whenever I travel I-75, I make a pit stop, there.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I have put a new fuel pump on and have a good 5.5 psi of fuel. The problem actually got worse.

I got a rebuild kit from edelbrock and rebuilt and soaked it and installed new rods and jets of factory size. It improved the situation slightly but the problem is still there.

It takes off in first gear fine, and pulls good through second. But if you're cruising slow in 2nd or 3rd, it will be good for a few seconds and then starts bucking and sputtering and sounds like its missing on half the cylinders. No smoke or audible knocking or pinging. it really never recovers afterwards until you shut it down.

I have a theory that is based entirely on gut feeling, that it is sucking the fuel bowls dry faster than they can be refilled

(Thoughts?)

Ok , so I got a tuning kit for my 500avs. My question is this:

It ran good with a 650avs but you could tell at certain times that it was too much carb. Since the 650 flows more air as well as fuel, when compared to the 500, do you think I need to lean out or richen the 500?

Like Josh said, the main circuit is partially plugged. You need to make sure both boosters are not partially clogged with debris. Spray them out so you can see that they are working well. You may have to use a couple of cans of cleaner to get the shavings out. Or pop out the booster and back flush with the jet out so the debris can go into the float bowl. These are real simple carbs so don't be bashful on the cleaning. Soaking won't help, you need to blow the debris out.

If it was just surging, that is another matter that can be fixed by using a stiffer "step up" spring.

At cruise 5.5 lbs is plenty of fuel pressure! I run the same pressure on the 440 in our 72 Imperial with an Edelbrock 600. No problems in a big heavy car.....never emptied the fuel bowls even with it floored passing semi's!

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

When I had it apart soaking, I mean I had it "APART". I mean stripped down to nothing but the castings. All individual pieces (boosters, squirters, etc.) all soaked and cleaned. All passages were cleaned with pipe cleaners and compressed air.

I have tried all the different springs and never made a difference.

I know I have good fuel pressure, but could my problem be fuel FLOW? I am using 5/16 fuel line currently. Also am using the dual feed line that goes to both sides of the carb.

There is nooo way that your engine is pulling more fuel than the carb and pump can deliver, unless the floats are adjusted waay too low and the bowls just not filling up. 5/16 line and a basic mechanical pump is more than enough (if it truely is delivering 5.5 psi, edelbrocks require 5-7 psi), the engine just doesnt have the demand for more of a supply... HOWEVER, if there is a restriction somewhere in the fuel line (collapsed hose, kinked steel line, clogged filter, etc..), you may get a good pressure reading but not enough volume to keep the bowl full...

I dont think this is the case because you say the 650 works fine. Im still concerned about the jets and rods not being correct (mentioned in your first post). If its available, try the rods and jets from the 650 in the 500 and see how that runs for you (may cause an over-rich condition). Also, is the check ball and weight installed correctly under the pump jet housing? Fuel bowl baffles installed correctly? There should be a spring on the accel pump and one under it as well... Most of the edelbrock operation is air speed and vacuum dependant, wich is why they are so sensitive to corrosion and carbon build up.

My buddy is haveing a similar issue on his small block chevy, the 600 (edelbrock performer) on it seems to go flat and lose power but not so much surging or sputtering, other times it runs like a raped ape. Put a real old 650 Carter AFB on it and works great, idle to redline?

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"if it aint broke, fix it till it is"
78 Plymouth Volare Super Six wagon
89 Volkswagen Golf GTI 16v
92 Chevrolet K1500 5.7
98 Ford Escort ZX2 zetech

The Edelbrock AVS is a great carburetor, but it has "issues".

Since your carburetor is relatively immune to adjustments, I would suspect that the needles and seats leak. In mine, this was the first thing I had to replace.

It is very sensitive to float adjustments. They need to be right on. If not, you have "problems" and they behave very inconsistently. Toward the end of my racing season last year, one of the tune up steps was to pop the top and check the float level.

They are very sensitive to fuel pressure. They can not handle more then 5.5psi. I run mine at 5.0psi to be safe.

If the air door opens to soon, there is no umph. After much fiddling, mine starts opening around 3500 rpms. If you loosen the screw up all the way, it starts opening at around 2500 rpms and your fuel mileage goes to hell.

The as shipped jetting should be fine for your setup. If your jetting starts going off the top end, you don't have sufficient fuel flow. People say a stock replacement fuel pump flows enough, I found this to be not quite true. In my car I had to upgrade to a BBM fuel pump and 3/8 fuel line.

Thanks to everybody who gave their input. I can't tell you how much this board has helped me over the years. I just recently joined so I could talk to all the gurus that this board seems to accumulate.

I started working with the tuning kit today. I put everything back to stock configuration so as to get a fresh baseline feel for what's going on.

Thing first thing I tried was all the way RICH jetting and rods. # 27 in the edelbrock book if you're interested. The problem had not changed as I had hoped. The reason I went rich first was because I figured if I go all the way rich and it gets better, then I can tweak it down. If I would have gone all the way LEAN first, I could've blown a nice round hole in a piston. So I figured better to err on the side of caution.

Well, since going rich didn't help, I'll start working my way lean from baseline. The first set I tried was #5 in the book.

EUREKA!!!

The problem was 95% gone! The only problem I was having now was a strong shudder whenever I lifted off the gas pedal. That was fixed by changing metering rod springs.

What a trip this has been. The beat I can figure is that when I had the 650 on it, it was flowing enough air, that it actually leaned out the mixture. Then with the 500 back on, there was a little less fuel being pulled, but a lot less air, causing a rich condition.

So the carb recipe that is working for me right now is...

.083 jet
.062x.052 metering rods
Blue springs
Accelerator pump hole furthest away

I sure hope that this helps somebody else one day. Maybe all this info will get them headed in the right direction!

Excellent! Glad you stuck with it....

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG