What Carb for Poly Stroker

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66 Sat,
I would encourage you to run the 625 AVS2. It has annular boosters in the primaries, which brings you to a new world in throttle response. This carb has smaller pri bores than your 600 Holley [ 1 7/16" v 1 9/16" ] for better response & mileage, with bigger secondaries when you want the power.
Chrys cars used Carter 4bbl AFB & AVS designs during the glory years, including on the Hemi.
I don't have any more direct comparisons as shown earlier, but in Roger Huntington's American Supercar book, 9 supercars are listed. These are NOT magazine tests, these are his own, unbiased testing. Quickest was the 68 Plym which ran 14.6....with a 750 Carter AVS on a 440. RH estimated the actual hp at 330. 3.23 axle. A 69 Ford Torino, 428 engine, Holley 735 carb, ran 14.9 with a more helpful 3.50 axle. All the others ran in the 15s.
He says this of the 340, AVS powered [ p. 132 ] : '' One of the swetest engines of the era was the 340...'It combined power & quick response with good fuel economy.' A 'Cuda with a lowly 3.23 axle ran 14.8 @ 96 mph....big block territory for a stock engine.

I do not know how long you have been in Oz, but various Aussie muscle cars were compared & the results published in Top Aussie Supercars. The 340 Charger, AVS equipped, v the 351 Falcon GT with 830cfm Holley. The Charger was 150 lb lighter, but down 11 cu in.
" We managed to 15.5s in the Charger, while the Falcon was battling to break 16 secs. Our test crew felt that the Fal lost a lot of time below 40 mph [ throttle response? ] - an area where the Charger is pretty fast."

" The 340 is definitely smoother at high revs & it doesn't haver the 351's tendency to lose tune after hard use"
That's great info Geoff and thanks but are we really comparing apples for apples here? These differences were solely due to the carburetors that the cars were running? Different cars, different engines.
The relevance to "losing tune after hard use" doesn't apply either. They didn't have an Edelbrock AVS2 650 on the cars in these tests from 1971 or whenever.
My Holley 1850 has been on the car for 4 years and hasn't needed any tweaking, except bigger jets when I got the headers. It drives to Willowbank Raceway (1 hr 30 mins), runs 5 or so passes, drives home again, doesn't lose tune.
I'm not against the Edelbrock in any way, I'm just trying to get objective information without clouding the issue.
I've been looking at this Brawler, 680cfm vac sec as well. Looks kinda cool, wonder if it performs well too?

QBR-67317 - BRAWLER 680 CFM BLACK W RED VAC SEC AUTO CHOKE​

QFT-BR-67317.jpg
 
66 Sat,
You choose what you like. I have been doing this for 50 yrs. Yes, not an apples to apples comparison. The Charger v GT test pitted a 625 cfm carb against a 830 cfm carb. The extra 200 cfm didn't do much, as the GT was slower in acceleration. During the muscle car era, 4 bbl Chrys cars were head of the pack for performance.....& they had AVS or AFB carbs.

When the popular small blocks were tested in 1969 to see if their developed HP matched the adv hp, only one engine did: the 340 & it made 20 hp more than adv!!!!!! Nearly 300 hp with a little 625 AVS, factory exh manifolds. The Ford 351 made the lowest hp & guess what carb it had...

img161.jpg
 
Does it have to be a carb? I'm seriously looking at a Holley Sniper 2 EFI for my Poly 318. Very little feedback on them other than installation instructions since the release this Summer so I'm hoping they might have fixed most of the issues the original had.
 
Hey guys I'm looking for some input on my next carburetor. It's a 66 Satellite with a 354 poly stroker. 3.58" Scat forged crank, Scat rods, Ross pistons 0.065 over, 10.8:1 compression. Poly heads with a little bit of porting, 1.94"/1.60" valves, Schneider solid lifter cam 264F (220° at .050, 0.450 lift). Topped off with a factory cast iron intake and currently a 1850 Holley 600 (vac sec). It's got headers, stepped from 1 5/8 to 1 3/4, 2.5" dual system.
Car is auto, 3.23 rear, used for hot street, cruising and at the track say 6 times a year. Weighs 3,640 lbs.
The car runs great with the Holley but I'd like to try something else. I've also got a 700 double pumper that I swap in and out and the car feels faster with the bigger carb (and made 7hp more on the chassis dyno, 341hp at the wheels vs 334hp with the 600) but the 600 is better on the street. I'm going to try the double pumper at the track early next year to see what difference it makes there.
There's so many choices my head's spinning.
I wouldn't mind trying an Edelbrock AVS2 but should I go 650 or 800? Normally I would think 650 but with the annular boosters would the 800 still work ok?
Or maybe a Holley 670 Street Avenger v/s?
Or a 650 double pumper?
Or a Brawler 680 v/s BR-67317?

I was leaning toward a 625 Street Demon but the reputation for poor build quality and a few design issues is putting me off.

Then there's boosters: straight, downleg, stepped, annular...man there's some choices out there.

I'm wondering what I'm leaving on the table with the 600 1850. I'd like the same reliability (super reliable), better low end and midrange, and maybe some more at the top (so basically more everywhere haha).

Any advice appreciated - I realise this is a very open question and one where brand loyalties are strong.

View attachment 1716170910

View attachment 1716170911
The engine now has 354 inches I take it. Now the original carbs on the 315 or 318 would have been a Carter 2 barrel or possibly a WCFB or an early AFB.
Your main use intention is street driving, so IMHO you would be best served using an Edelbrock AVS2 650 carb. On the street you will see better response and fuel economy. Now that will mess in Rusty's Corn Flakes, and I have no interest in if that occurs clockwise or counter clockwise, as I do not intend to offend. A double pumper Holley was designed and intended for race use. The double pump shot helps response on an engine with a lot of cam and carb get through the stumble on mashing the throttle to the floor.
Yes the Holley 750 or the AVS2 800 are most likely to give better times at the strip, but economy will tend to suffer. The AVS2 not as much as the Holley. Yes I know you can tune for mileage, but the reason for the big carb is track time.
Racers use the Holley because it is quick to change tune at the track. Between 750 CFM carbs between Rochester, Carter/Edelbrock or Holley, the Holley may flow slightly more air.
For Holley carbs tuning you get the Strip Kit with a selection of jets and air bleeds to tune for atmospheric conditions at the track.
Rochesters have been more difficult to get jets and metering rods for as they were more intended for OEM use, and tuned for that application. Since the introduction of the Edelbrock Quadrajet series, they have calibration kits for them.
The Carter/Edelbrock AFB and AVS carbs have calibration kits available. One nice advantage with these is that the tune can frequently be adjusted with primary metering rods which can be changed without removing the carb cover. Just remove the air filter housing and the metering rod and piston covers with one screw in each. No fuel spilled.
The 800 AVS2 can be tuned easily to give street and race performance, but I would urge caution about over carbing a street driven engine. Again, on the race track is one thing but how much power do you really give up.driving on the street.
As enthusiasts we need to be responsible. Our hobby is under attack and we do not need to toss nitro on that fire. Doing burnouts, fishtailing and drifting with lieberloon wokie tokies watching on the sidewalk, is not a service to any of us. To the police and law makers they see no difference between any of us. Similar was the impression of motorcyclists. Some thought if you were riding a motorcycle your mindset had to be to come and rape their daughter or wife, so they would try to run you off the road.
I would chose a bit less power at the track as you give up basically nothing on the street.
Considering that a carb is a quick and simple component to change, you could run the 650 on the street and swap on the 750 or 800 for track days. Run what you have already in the shop.
At this time it is not wise to spend money unless you have to. I hold minimal faith for a positive direction of the world over the next 5 years to 10 years.
 
Thermoquad.
The difficulty with the Thermoquad aside from age is that like the Quadrajet, those big secondary throttle plates will not clear the factory manifold. True that a carb adapter could be purchased if there is enough underhood height.
IMHO for mainly street use, go with the AVS2 650. Nothing wrong with the Holley style carbs. My 289 2V did require a bowl gasket every spring or at minimum tighten bowl screws as the gasket dried and shrank over the winter. For me the Edelbrock performer 600 on an Airgap manifold cured that issue. I believe there are better gaskets available now for the Holley float bowls.
 
OK thanks for all the replies, AVS2 650 is looking like a good choice but will it work with the square bore manifold I have?
View attachment 1716171154
I am going to open the up the center section and port the manifold as per Gary Pavlovich's advice but that might not be for some time.
The Edelbrock carbs have a dual bolt pattern, so should ba a dropon that way. The AVS2 650 should be a bolt on. The AVS2 800 likely requires opening the secondary bores in the manifold.
A young lady that lives here has a poly engine with a 6 pac her Dad built. Otherwise it is stock.
 
66 Sat,
I would encourage you to run the 625 AVS2. It has annular boosters in the primaries, which brings you to a new world in throttle response. This carb has smaller pri bores than your 600 Holley [ 1 7/16" v 1 9/16" ] for better response & mileage, with bigger secondaries when you want the power.
Chrys cars used Carter 4bbl AFB & AVS designs during the glory years, including on the Hemi.
I don't have any more direct comparisons as shown earlier, but in Roger Huntington's American Supercar book, 9 supercars are listed. These are NOT magazine tests, these are his own, unbiased testing. Quickest was the 68 Plym which ran 14.6....with a 750 Carter AVS on a 440. RH estimated the actual hp at 330. 3.23 axle. A 69 Ford Torino, 428 engine, Holley 735 carb, ran 14.9 with a more helpful 3.50 axle. All the others ran in the 15s.
He says this of the 340, AVS powered [ p. 132 ] : '' One of the swetest engines of the era was the 340...'It combined power & quick response with good fuel economy.' A 'Cuda with a lowly 3.23 axle ran 14.8 @ 96 mph....big block territory for a stock engine.

I do not know how long you have been in Oz, but various Aussie muscle cars were compared & the results published in Top Aussie Supercars. The 340 Charger, AVS equipped, v the 351 Falcon GT with 830cfm Holley. The Charger was 150 lb lighter, but down 11 cu in.
" We managed to 15.5s in the Charger, while the Falcon was battling to break 16 secs. Our test crew felt that the Fal lost a lot of time below 40 mph [ throttle response? ] - an area where the Charger is pretty fast."

" The 340 is definitely smoother at high revs & it doesn't haver the 351's tendency to lose tune after hard use"
Last time I checked, which was like Yesterday, all the new AVS2's have annular boosters...that engine will be fine with the 650.
 
I would throw out there that I have a 2×4bbl. Poly intake, & a pair of slightly rough WCFB's, but Your life will be simpler w/the 650 AVS2.
:thumbsup:
 
I am a TQ fan, as many on this forum know. I purposely did not recommend it for the reasons Dale has described above. The adapter reqd to fit to the Poly intake would kill a lot of flow & probably cause turbulence that would affect cyl-to-cyl distribution.....& reduce
power.

From day one in 1957, Carter very cleverly with their 4bbl carbs, made models with small primaries & larger secondaries. Small pris for response & mileage, the bigger secs for power. A no-brainer isn't it????

When Edel decided to get into the carb business, they reproduced the Carter AFB/AVS design.
Reason could have been because very man & his dog were already making 'better' Hs.....
A little known FACT is that Edel used to sell H carbs looooong before they started reproducing the Carters.
 
I ordered a 650 AVS2 yesterday morning - should be here in a few days. I've been reading about the fuel pressure needing to be between 4.5 & 6 psi. I have no idea what my factory style mechanical pump puts out. I might try it and see how it runs before I buy a regulator. I also have to buy (or I might make one) a timber adapter to replace the aluminum one that I have at the moment. Apparently the Edelbrock won't like the heat transfer from the cast iron manifold to aluminum spacer to aluminum carburetor (I have no issues with my Holley in this regard).
I'm very excited to see how good the throttle response is going to be after hearing all these good things about it.
 
Mate,
You will be veeeeeeeeeeeeeeeeeeeeeeery happy. You will NOT need a reg. The quoted fuel pressure figures by Edel are for the purpose of establishing the fuel level [ 7/16" ].
Every carb is designed to work with a specific fuel level in the fuel bowl that is relevant to the discharge point at the booster. Called the spill height, it is usually between 1/4 -3/8", ie the bottom of the booster discharge is above the fuel level in the bowl by that amount. Reducing the spill height [ raising fuel level ] richens the fuel level slightly & vice versa. One good feature of Holleys & clones with sight plugs is setting the fuel level.
Fuel pressure, needle & seat diameter affect the fuel level.

When Edel copied the AFB/AVS they did not change the fuel inlet system in any way shape or form.
All of the parts are interchangeable: needle & seats, floats.
Carter produced a chart showing float adjustment for as high as 10 psi [ see below ]. I have run Carter carbs with 10 psi of pressure, zero problems. The Edel will also have no problem with that much pressure because they come with small 0.093" n/seats; smaller n/seats control fuel level more accurately.
Your pump is problaby outputting 4-8 psi & I would just run it....No reg needed. Don't forget THAT pump was used to feed Carter carbs....& had no problems doing it.
Every Edel carb I have encountered needed the float level to be adjusted. I suspect rough handling during the long journey is the reason.
So I recommend you check the setting. You will NOT need any gaskets if you are careful. Take pics/drawing of the linkages. If you lose a circlip I can send you some spares. Give me a holler if you get stuck.
 
That is a rare piece. Carter also made some like that for the Pontiac race program. Rare as the Autolite Inline 4V carbs.
Yeah. Like the super rare Cross Boss dual inline four they offered. This would look good on a poly. lol
DUAL CROSS BOSS.jpg
 
Below is the chart for Carter/Edel AFB/AVS fuel pressure v float level.
Note in the text that a 7.5-8.5 psi competition pump is recommended for performance applications.

img327.jpg
 
Last time I checked, which was like Yesterday, all the new AVS2's have annular boosters...that engine will be fine with the 650.
Annular primaries but regular secondaries. With the Edelbrock AVS2 models they build them with secondary venturis which the AVS do not have.
Edelbrock also has their new VRS 4150 series modular carbs. These also have annular boosters. The carb is also 1/2" taller giving a longer venturi length which may also contribute to better fuel atomization and thus vapourization. Sizes in 650, 750, 850 and 950 CFM ratings.
 
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I wonder if clockwise or counter clockwise is more conducive to turd removal? I guess we may never know. lol

If we're keeping score, my vote is for the AVS2 650 for the reasons others have put forward.

As for the question quoted, I wonder if it matters whether the individual is from North America or 'down under'? What about a North American in Australia and vice versa? Or is it food dependent (Vegemite is just plain nasty)? I think I've just found my next research project to scam the government out of another bazillion dollars. Thanks guys!
 
If we're keeping score, my vote is for the AVS2 650 for the reasons others have put forward.

As for the question quoted, I wonder if it matters whether the individual is from North America or 'down under'? What about a North American in Australia and vice versa? Or is it food dependent (Vegemite is just plain nasty)? I think I've just found my next research project to scam the government out of another bazillion dollars. Thanks guys!
I've heard vegemite is nasty, but I've never tried it. My son is living in Australia now and says they certainly have some "different" food. He does all the cooking in their household. He whooped up some of my wife's sausage gravy and biscuits not long ago and he said they oinked it down like they hadn't eaten in days. They'd never had it.
 
Your son can have my Vegemite, I hate the taste.....
What state/city is he in?
 
Yeah. Like the super rare Cross Boss dual inline four they offered. This would look good on a poly. lol
View attachment 1716174005
Too bad we did not know back then what we know now. Just as I started working you could go into a Ford dealer and order one like shown or the single carb. For Mopars, a Challenger TA or Cuda AAR. Put in storage on blocks. Or one of the wing cars. A couple of those now with basically 0 miles and retirement would be a bit easier.
 
Too bad we did not know back then what we know now. Just as I started working you could go into a Ford dealer and order one like shown or the single carb. For Mopars, a Challenger TA or Cuda AAR. Put in storage on blocks. Or one of the wing cars. A couple of those now with basically 0 miles and retirement would be a bit easier.
I know, right? Too bad wisdom usually only comes with age. lol
 
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