For the street I always leaned toward the smaller pot as the off-idle/mid-range response was better.  But for WOT the 351 might be able to use the 650. 

Those who actually know something might chime in.

BB

Run the 600.  I run a 500 on my 289.  The 351 is only another 62 cubic inches larger, or about 20% bigger.  Going to a 600 from a 500 is also 20% more.  If your engine had any ability to rev I'd say the 650 would give you more top end, but with stock heads, manifolds, etc. you're going to be done at 5,000-5,500, so there's no point.

I would second running the AVS as well.  That's what I run and I'm quite happy with my carb.  Edelbrocks tune intuitively, just remember to grab the tuning kit along with the carb. 

Also, make sure to get your timing set right (not just base, but max. advance and speed of advance) or carb tuning is sort of like urinating into the wind. 

I have the 351W in my 68, .030 over, 5.0L heads, Performer intake, MSD ignition, JBY shorty headers 2 1/2" exhaust, Flowmaster Delta 50 mufflers, and I have the Edelbrock 1406 - 600 cfm. The combo works very well for me. I think you'd be fine with that one. I don't know anything about the newer carbs, just that my setup works great for me.

DC wrote:

My experience says that the smaller carb is always easier to tune on cars that are street driven and require a wide range of acceptable performance. I know that 50 cfm out of 650 doesn't sound like much, but it can mean a nagging bog or hesitation. If you are going to concentrate on wide open throttle and peak HP, go for the big one. If you want to enjoy driving from your driveway to the car show, the 600cfm is good. I have a 600 cfm on two Mustangs. One is always above 4000 rpm (shift at 8000) on the track and makes 430 hp. Second one is street driven and works from idle to 6500 rpm. Both work great for what they do. Since the street car does not fall under any rules it makes more HP than the race car which is limited by valve lift and other silly things. The cam on the race car is aggressive and needed a lot of carb work to idle well enough to get around the paddock. The cam on the street car has more lift and idles without all those mods to the carb. And like 6sally6 says Barks (revs) like it has an aluminum flywheel. Wait a minute it does have an aluminum flywheel.

Sure hope to see you at the MSBB this year.  Maybe go for a ride in that "noisey-old-car" of yours!
6s6
 

I also read the reviews, of the avs 650 Edelbrock  on summit racing. They seemed very good, for the most
part, a lot of the reviews were people who replaced the 1406 edelbrock (600 cfm) with the edelbrock
1906 avs (650 cfm).  They are saying that the avs had better response on the bottom end and mid range
compared to the 1406. Something about a new design. Normally I would go with the 1406 (600 cfm)
no questions asked from past experience. After reading the reviews,I kind of makes you think. It can be
confusing,I have been trying to do my research on these carbs. I will be cruising most of time, no drag
strips. Drive ability  will be the main issue ,I really don't want something that will bog down when I hit the gas.
Also fyi I will be using a new pertronix stock look distributor with ignitor 1 ignition and pertronix epoxy coil.
I have time, I won't be starting the swap till next month, I will probably use my 500 cfm (from my 289) to break the camshaft in. It seems the more I get into this project, the more I do and the more I'm spending. I did
power brakes ( drum brakes) two years ago with this forums help.Now I'm thinking with the engine out
it would be  a good time to do a  disc brake master cylinder  on the booster, lines and proportioning valve.
I will get my son to take pictures and try to put them on this forum, once I get started. If anyone has the time
check out the reviews on summit racing and see what you make of them. As always THANKS FOR ALL
THE GREAT INPUT! This site has been a great asset for me. mustang stu
 

zakdaddy99 wrote:

I know this has been a discussion of Edelbrock carbs to this point, but you might consider the Summit line of carbs. I have a 302 with GT40 heads, Weiand Street Warrior intake and factory HO roller cam. I had a 570 Street Avenger which I did not like. Went with the Summit 500cfm carb and could not be happier. Great throttle response. The 600cfm version should be what you need.

Also consider the M/E Wagner adjustable pcv valve. A bit spendy but made a huge difference in drive-ability. The 2 dollar parts store valves are junk, IMHO.

  I had the 570 Avenger too and didn't like it either.   I also liked the Summit carbs review on Summit Racing. 
 

If you want a carb that you can bolt on and it will be 85-90% right out of the box, run an Edelbrock.  Over the years I've messed with just about every kind of carb there is on everyhing from cars to boats to motorcycles, etc.  Holleys biggest claim to fame is that they are easy to tune, yet you read post after post of guys that can't seem to tune them.  I think the truth is that they sell a lot of tuning parts, which isn't the same thing.  I was always able to get them to work eventually, but it often took quite a lot of fiddling and changing parts. 

By contrast, in my experience you can get an Edelbrock dialed in by swapping jets and metering rods.  Either type of change will take you maybe 5 minutes and doesn't involve removing or draining the carb.  I've swapped step up springs and never seen an appreciable change.  Possibly my combination just didn't require it, but I've gone from weakest to stiffest and no difference in how the car drove.  I've also never seen the need to swap holes on the accelerator pump to cure a lean or rich bog, they seem to be right from the factory for most applications.  The design just seems to be self adapting to a large degree.  Often a touch rich on the base calibration, but that's better than lean, and easily remedied. 

Also, IME if you run an automatic a vacuum secondary carb will work fine, but if you run a manual trans a mechanical secondary seems to work better.