Hey all,
Well here we go again with another Edelbrock piece of [censored] carb.! Last July I bought another Edelbrock 650 AVS carb. It seem to run fine then but this is a new year and Murphy's law says what can happen will. So this year the car has been running sluggish, there is a dead spot around 30-40 mph, and takes about 20 seconds to start when running around 190 and just totally runs like crap! So I started with taring apart another carb. to dissect and see what is wrong. Last year I took it apart to check floats and that is all i did. So this time I focused in on maybe channels had gotten something lodged it somewhere. One thing I found was someone had changed out the .095 primary and put in .098's. I know it wasn't me unless I did it over the winter and in my sleep! Back on and test still no better. Back off again. Pull out my old Carter 625 afb put everything back in and tried that one. Ran better but there is just something wrong with this carb. To make a long story short I decided to transform an AVS with AFB parts. After all Edelbrock did say that an AVS is the same as an AFB with a few mods. There is other parts that are different namely all 4 clusters. There is a small jet in the primary and secondary clusters on the AVS where the AFB does not have so I installed them in the AVS and put in the .100 main jets cause that is what is in the AFB's and put in now the new .0705 x .047 rods instead of the .068 x .047 roda that are in the AVS. I was just fed up with the hard starting when hot that my Carter did not do. Unfortunately I can not change it all together. There is a vent in the old Carter AFB's that lets the fumes out into the atmosphere where the newer design Edelbrocks do not have. And you wonder why the carb. boils gas over into the intake when hot? Well after the switch I started it up and ran pretty good. I did notice right off the back after it got warm to hot that now where my fuel mixtures screws were just 1 1/4 turns before are now at 2 1/4 where most carbs. should be. So my transformation is a success. Car runs alot stronger and after 30 mins. of idling and driving it and a 10 min. shut down it fired up in approx. 3-5 seconds! I hope those lying assholes at Edelbrock do not find out what I already know! If this didn't work then I was gonna go against my belief in keep original looking and either buy a Holley or another older Carter performance carb. from the 90's. I hope everyone takes my little adventure I had and uses it for a reference in case you have a thought to try it! Good Day!!

Good stuff! & I would try the cluster and the rod/jet changes seperately as I am a firm believer in one change at a time. Mainly I'm real curious on how the cluster change affected it. Thanks Dave!

It is such a shame that a really good carb design like this has been allowed to become so obsolete. They have not have any meaningful design or tune upgrades in decades. Heck even old Carter engineers have went to work for Holley.

Keeping an original look is the ONLY reason to mess with one of these dinosaurs. And I say that with sadness.

Now I know that there are guys that bolt one of these carbs on and are happy with the way their cars run. BUT! Unless they have tried one of the more modern design carbs too, they have no idea just how good their engine COULD have ran.

And just to be clear, I will say it again; the Carter design is not a bad design carb. It is just that it is totally behind the times in design features and tunes. Not to mention how much more difficult they are to tune and to find tuning parts for.

Flame on..................

So it was fine last year? Sounds like you took it apart and the cleaning corrected your issue as much as anything.

Hey all,
Robert I understand what you are saying about try one thing at a time but after taking this carb. apart a few times and I did pull everything out
and blew through every channel and after reassembling it it still ran like crap. Thanks to the manual on Edelbrock /carter carbs. and sitting last night while going through it made me think of the clusters from one carb. to the other. I compared the primary cluster on the AFB TO the AVS and it appeared that the brass tubes were the same size but what the book referred to stood in my mind early this morning about jets in the clusters. When I looked at them side by side there was a small jet in the AVS but not the AFB so that is when I decided to just go all out and transform the carb. These Edelbrock carbs. are fine if you have a stock engine with stock cam specs and 15-19 inches of vacuum but put it on an engine that has a bigger cam with duration at .05 above say 225 and vacuum below 14 at idle then you will have a problem. These carbs. are designed with economy in mind and that is why on some engines it will run lean or the engine will run hot. I do believe Edelbrock did screw up the design on this carb. They should have kept the same clusters and jet sizes and rod sizes if possible with the Carter design. And only changed the secondary's.
The adjustable sec. butterflies and the 1.750 throttle plates. This change I made is like having a new carburetor with my own design. Now I will probably have to pull out the .098 secondary jets which I wanted to leave in while doing my test run to see how it would perform at idle and low/ cruise. I am going to up the sec. jet size to .101 and see how it does with that. Edelbrock needs to be informed of this so they can re-design there 650 AVS, and I am pretty sure that their 800 AVS also have the same design. I could be wrong seeing I haven't had any experience on that particular carb. Happy Mother's day to any Mothers on this web site!!!

Looks like I will stay with the .098 in the secondaries. 62maxwgn, Is that the jeopardy tune I am hearing from you? I will need a week or so after sudden temp. changes to give accurate results. oi will reply back at a later date. Thank you! Dave