I’m looking to wake up my 73 351c 2v. It’s an absolute dog. I’m looking to keep the cost down. I don’t really want to tear into the engine farther down than the intake but I’m considering a mild cam in the future if the rest of the project goes smoothly. I’ve decided to go for the Edelbrock 2750 performer intake but debating several 4 barrel options. I’m wanting annular boosters. I’m considering two options, the Summit M2008 series or the AVS2. Problem is the CFM. The Summit comes in either 500 or 600 for around $400, whereas the AVS2 comes in at $370 for the 650 and a whopping $550 for the 500 cfm. Obviously the summit is the “cheaper” unit, didn’t they used to be in the $250 range? $400 seems steep. I’d like the cheap AVS2 carb but I’m worried the 650 will be too much carb for my engine without a cam. I’m thinking no cam the 500 is probably better as a package but the 650 on the stock internals would be good enough until I put the cam in if I decided to do so. Any ideas or alternate suggestions? Thanks!
Well either of those will be down on power significantly compared to a Holley 0-1850 600 CFM carburetor. I don’t understand why anyone would use anything else.
This. I have loved that carb/intake combo on my otherwise stock '70 351C 2V for the past 5 years. I did recently have an issue with mine which was from letting it set too long with ethanol gas in it, but a good cleaning and swap of a couple of the rubber bits cured that. Back to running like a dream. Won’t make that mistake again.
I’m looking for reliability and ease of maintenance/tuning over pure performance and that’s why I’m wanting an Edelbrock or Autolite style. If it wasn’t for the 1406 having no annular boosters I’d be choosing that.
I’ve misread your post. I’ll do some more research on that one. It is in the appropriate price range. I’ve just heard the Holley carbs are a little more fiddly to mess with and rebuild.
The Holleys that I have used were extraordinarily reliable. Yes if you let the gas go bad you will have major problems. As long as you don’t do that you won’t.
the 1850 is a good basic carb, but it is designed to fit nothing in particular, and its a vacuum secondary so its not designed to make max power either. It needs someone capable and confident enough to tune it, and not just adjust the mixture screws! most people are not comfortable opening up a carb and changing jets and power valves, yet alone squirters and cams. some of these other carbs are more forgiving
I didn’t do any of that. I just plopped it on the engine and enjoyed decades of trouble free use.
Wow. You are on in a million! I sold at least a hundred of those when I worked at Super Shops in the mid-nineties and we sold them with a disclaimer saying they required tuning that include jetting, power valve and other changes. Most cars would run with that carb out of the box, but they sure would not run very well, usually really rich.
I bought mine from Summit Racing. I think it was around $100 including shipping. I put it on my 289 Cougar with a 289 A code which I put Cyclone headers ($69.95 from Summit) and a Eldelbrock Torker that I bought at the Pate swap meet for $50. New ones were around $79 from Summit.
Then I proceeded to put 400,000 miles on that Cougar over the next twenty years. I sold that car around 1991 and a guy drove it to Amarillo.
I bought one new from a local speed shop and installed it on my first big block ( 390 4V-IP ) 1969 Cougar. Engine ran perfect with the 1850 right out of the box - necessitated because the original Autolite 4300 was leaking fuel. I think the CFM was about the same as the original Autolite - 600 to 650 CFM, and I even overhauled the carburetor once. Sold vehicle with the Holley still on it, and it continued to be trouble free.
Installed another one on a 1971 Lincoln Mark III ( 460-4V ) when that Autolite began to ( you guessed it ) leak gas, and even before that point it was NOT running smooth. That Holley ( again decades after the Cougar ) was also acquired from a local speed shop ( but this time, all they had was a shiny chrome version ) and again it ran perfect right out of the box - it had an electric choke ( which was actually easy to set-up and wire into a keyed power source ).
If you do the math, you’ll find that the 600CFM carb is exactly what you need for up to a 351 engine.
I ran a “little” 580(?) CFM 1850 series Avenger on a 331 that I built about 10 years ago, with an F303 Ford roller cam in it (.512" lift), and it was a SCREAMER! When the secondaries kicked in it ran like a big block! It gave me a very wide torque band and over 300HP at the rear wheels at 5000 or so. Wasn’t the most you could get out of this package, but I needed reliability and good street manners…which this package delivered in spades! It didn’t lope, but it did purrrrr!!! About 18mpg driven sanely…hard to do!
LOVED IT!!! Need another…!!!
Steve
The online “formulas” are hopeleesly wrong. I have used a 780 CFM carb on a 289 at the drag strip - it works fine. Shelby used a bigger Holley on his 289 - I don’t recall the exact CFM but it was bigger than 600 because he knew what he was doing.
That said a 600 CFM carb is about perfect for a 289 - or 302. If I had a 351 or 390 I have and will use a 750 or 780 Holley.
Royce,
It’s all in what you need…or in some cases what you think you need…! 
I’m speaking from a daily driver aspect, as you eluded to, which is 99.9% of our cars usage. These days, most owner’s cars will never see a road or drag track ever. Out to cars n coffee events or local car shows where they can brag about how many miles they DON’T have on their cars…
Someone mentioned the 600cfm carbs working out of the box… for most 302-351 cars, of any brand, this carb was a make it work fast solution. (although I bet that MANY noticed no more performance than with the 2V setup they took off their car!) Maybe not so much today with sloppy unsupervised production facilities putting junk in boxes…
That 1850 was around WAY back in the 70’s when I was in high school with my first 327 Chebby! Didn’t know much about carbs other than in mini-bikes and lawn mowers…but I figured it out way easier than trying to tweek an AFB!!! It just worked. Yah, it may have been slightly over jetted, but with gas at a whopping $.35 a gallon, it wasn’t yet a large issue… Idle screws and a vacuum gauge were all you needed to mess with!
After my experience with a 69 390 XR7 I would never run the 600 no matter what the parts books say, on a large FE! What I loved is the 725cfm replacement carbs…C9AF-U. Dirt cheap (at the time), everywhere at the swap meets, and they would work nicely on 351 and up engines for day to day operations and perhaps a little more.
Now they are suddenly a “correct” Cobra Jet carb…and expensive as all getout!!! Stupid people…internet is failing them…!
The bottom line is that people as mechanics need to read and understand these air mixers and make proper choices when tuning them…AND utilize an hour or two on a chassis dyno to make them right for your car if you can afford it…but you should afford it!! It is not rocket science!
Drive them! Your road is getting shorter every day!!!
Cheers!
Steve
I have spent a lot of effort tweaking 351c-2v Cougars. I have found that right around 650cfm, vacuum secondary, is the sweet spot even with a stock cam. This is enough to notice a noticeable bump in power. But you need to install long tube headers in conjunction, otherwise you are just wasting your money.
That’s not my experience at all with the Street Warrior version. As plug and play a carb as I’ve ever seen.
I appreciate all the advice guys, I was very tempted to go with the 1850 after all of your recommendations. However, I managed to find an old 1406 for $50 on marketplace and I jumped on it. He said it came off his small block Chevy that was running that he pulled for a big block swap so we’ll see if it’s any good. Good physical condition so worst case scenario is rebuild I imagine. No annular boosters like I wanted but I’d rather have $350 in my pocket for maybe patching the giant hole in the drivers pan! The whole car is pretty ratty but it was running and driving and very cheap. I’ll let you guys know how it performs once I get my hands on that intake.
The 1406 is just fine for a stock cam / exhaust. Good luck!