I just need to get this out so here it goes. forgive spelling and the length

I decided to replace my old 650 carter AFB carb thats having issues with a new 650 ASV edelbrock. Go across town to a hotrod shop and pick on up slap it on only to find out it is defective. Take it off, take it back and they tell me "yeah, out of 20 we have sold ten or so have had problems" get a 600 which they say have been much more reliable and have less issues. Get it home, slap it on only to find that the truck has fluctuating idle, power surges through the rpms and some back fires out the exhaust. Check all vacuum connections and gasket seals cant find any leaks.
Next day I take it to some guys for their opinion they think another bad carb but i cant believe it. Call the hotrod shop and tell them what's going on they say limp it over and they'll check it out. So today, i get off work a little early fight the traffic across town, 15 miles or so on surface streets, to hopefully get this resolved. Guy comes out takes one look and says oh your fuel filters dirty, and it was slightly but not bad, thats your problem. I say the previous two idled just fine to which he says "thats just coincidental, get new filters take the carb apart and clean it out and you'll be fine." I say any ideas if this doesn't work "it will, he says."
So i fight traffic back home and spend all evening replacing both fuel filters and cleaning out this damn carb, which was pristine inside by the way. Get it all back together around 10 pm and pray it works. The moment of truth comes and goes with exactly the same result, idles between 800 and 1000 spray carb cleaner all around the gasket and points where it could leak but nothing. Spray a little down the throat and it smooths out but goes right back to the same old thing after a sec. I quit for the night because ill **** off the neighbors running that thing up so late trying to figure it out.

Well Im not as frustrated now but I really just cant believe it and my truck still isnt running well.

Ian

 

Just a thought, but after dealing with the Edelbrock Performer on my Fury, I've learned that Edelbrock carbs are tuned for sea-level. If you pull it out of the box and bolt it on without tuning it, it might not run right. I had to swap out needles, seats, and springs in mine and set it back 1-stage leaner on both power and cruise modes before I finally got it to run decently... Seems to be more of an issue in higher altitudes though, and I'm about 2,000 feet higher up than you... Again, just a thought...

 

Time to buy a Holley.

 

I think it's interesting. Everybody's always talking about how easy a carb is, how much more reliable it is than EFI. Would you say that's true for you right now? I think carbs are extremely hit or miss. I've had similar problems with 2 out of three motorcraft 2150's I've had, and they're supposed to be the simplest most idiot proof carbs you can get. I'm upgrading to EFI.

To be honest, if you were having problems in the first place, it may not be the carb. My brother's truck was very hard starting, rough idle, power loss in acceleration. We rebuilt the carb, tried tuning it, and even swapped it out. It turned out to be the valves.

 

I switched from the Edlebrocks to Holleys and I"m much happier now.

 

how do you tune the air fuel ratio? can you use a wideband gauge with a carb? how do you do it with out a wideband gauge? is it all based on vacuum?

 

This is for a a 650cfm AVS - the website doesn't list a 600...
http://www.edelbrock.com/automotive_...806_charts.pdf

These charts are using vacuum readings but when I did mine, I just tuned it by ear following the recommendation of an old Chrysler mechanic, then I set the timing with a vacuum gauge...

 

it wasn't having these issues before so i dont know what to say. I started it up today and it warmed up great and then as soon as i tried to tune the air mixture screws it started with the up and down rpm making tuning difficult.

 

First of all there is no such thing as a 650 CFM CARTER AFB. You either had a 600, 625 or 750.

The AFB and AVS style carbs are the EASIEST carbs to work on and rebuild.

Why did you replace the Carter? If the truck wasn't running bad with it, why replace it? You won't notice any improvement going to an Edelbrock.

I take it you aren't able to re-install the Carter to see if the problem either goes away or remains?

I think you have problems elsewhere that are somehow being blamed on the carbs. The problems you describe sound like a flat cam, stuck valves or a huge vacuum leak.

Josh