what motor combo... specs.
carb choice and slick size
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what motor combo... specs.
moper
Well-Known Member
"AVS" is Air Valve Secondary. The secondaries are broken into two parts: the throttle plates and shaft, which is mechanical, not vacuum operated secondary; and the spring loaded plate that sits above them. When you floor it the secondary throttle plates slam open, but the spring controlled door above them doesn't. That air door lets the air speed come up smoothly so there is no need for a secondary accelerator pump and no chance of going over-rich when it's floored. Overall, it's a much better all around carb than a Holley, and will make the same power as a similarly sized Holley if both are properly tuned. But it will also idle cleaner and get better gas milage.
I run the Avenger series carbs too. They are great but again - will require tuning. Also - the 670 Avenger is a wet flow rated carb... So the direct comparison size-wize to a 670 Avenger would be the 750 AVS. IMO - a little large for what you're doing. I'd run the 570 Avenger on your car. If you go to a 3.91 gear or steeper, the 670 or 750 will get you better ETs. but with the mild gearing the smaller carb will produce better results.
I run the Avenger series carbs too. They are great but again - will require tuning. Also - the 670 Avenger is a wet flow rated carb... So the direct comparison size-wize to a 670 Avenger would be the 750 AVS. IMO - a little large for what you're doing. I'd run the 570 Avenger on your car. If you go to a 3.91 gear or steeper, the 670 or 750 will get you better ETs. but with the mild gearing the smaller carb will produce better results.
firefighter1
Well-Known Member
I have a competition series carter 650cfm carburetor if interested? $100+Shipping. PM me if interested. Good luck!
Carter's have mechanical operating secondary butterflies that have a velocity air door above it loaded on a spring. When this air valve is overcome by demand it will open. It is not a vacuum sensitive item by a air velocity issue. AKA, air demand for the engine.
The spring on the secondary side is an easy adjust for sooner or later openings with 2 screwdrivers. The AFB is a counter weighted air door that is not easy to readjust. Sometimes the quick opening of the valve will cause a flat spot. Mods can fix this though it is a pain to do and expensive if you screw it up or have it done for you.
The spring on the secondary side is an easy adjust for sooner or later openings with 2 screwdrivers. The AFB is a counter weighted air door that is not easy to readjust. Sometimes the quick opening of the valve will cause a flat spot. Mods can fix this though it is a pain to do and expensive if you screw it up or have it done for you.
Moper, do you know this for a fact that the Carter's/Edelbrocks are not wet flowed and if so, via what information outlet.
C130 Chief
Mechanical Genius
Many here have personal preference Holley or Carter (Edelbrock). Either one will do fine, the engine really doesn't care. Either carb, correctly calibrated will make the same power. Fuel+air go in, torque comes out. It's that simple. And to be honest, running 1/8 mile drags with 3.23 gears, it really won't matter.
The Edelbrock 1806 is pretty close to what Mopar installed on the 340 originally. You decide if that means anything. A Holley 670 Street Avenger would work well also. (1971 340's had a 750 CFM Thermoquad, with an "Air Valve Secondary")
I would keep the slick diameter as small as you reasonable can given your gears. Something in the 26x8 neighborhood. Slicks on a 14" rim?!?
The Edelbrock 1806 is pretty close to what Mopar installed on the 340 originally. You decide if that means anything. A Holley 670 Street Avenger would work well also. (1971 340's had a 750 CFM Thermoquad, with an "Air Valve Secondary")
I would keep the slick diameter as small as you reasonable can given your gears. Something in the 26x8 neighborhood. Slicks on a 14" rim?!?
The biggest problem your going to encounter is the 3.23 gear and 1/8 mile. If this is what your going to go with, as mentioned above, stick with the shortest slick you can find. The larger you go in diameter, the higher it makes the final drive ratio. With that in mind stick with a smaller carb say 570-650. This will make your combo rev quicker. A 4.30 gear I would go with the 750 DP and 28" slicks.
moper
Well-Known Member
The CFM ratings for Edelbrock carbs have never changed and they were introduced in the early 90s. Wet flowing was a specialty carb shop deal until around the mid 2000s. BG's Demon line was the first I know of wet flow rated carbs being marketed to "mass market". To add confusion, only some of Holley's carbs are wet flowed. I know the HP line and the Avenger is (and ususally it's advertised as a "premium" feature), but the older design 3310, 4150, 4160, and 4500 series are not.
It's a much more accurate method of rating. Very generally you can take off 12-13% from the dry flow number for the fuel. So a 670cfm Avenger is about the same capacity as a 3310 750 or 1407 Edelbrock . An 870 Avenger is around 975 dry.
The key is to have enough airlfow to support the power level, but also to have enough air speed at idle/low rpm to be responsive. That's the line you try to walk. Like C130 says - any carb will work, but with 3.23s running and 1/8th mile I'd be surprised if the engine will even reach 4500 in 2nd gear at the stripe. So additional flow capacity to make power beyond that is only going to help ina street race or 1/4 mile track and it will slow down response at cruise and off idle.
You want it to run it's best at the track put a DP carb on it.
With that gear, you sort of run it like a glide. 3000 stall would be fine. In fact, that gear will work the converter harder!
ALL carbs will require tuning to run best.
Fuel economy suffers with DP carbs is a load of trash. Kyles Demon with a 360, XE268H, small valve J's, LD340, 750DP, 2.94 gears and a 2500 hughes converter got 20mpg on the highway and around 15 in town as long as you drove it like a sane person. Fuel economy is DIRECTLY related to your right foot!
That Demon ran 14.00 at 104+ mph in vegas with a rotten 2.25+ 60' and a fat tune up because the air was 4500+. It was babied out of the hole because of the 7.25 pegleg rear. It wasn't full throttle until about 80-100' out. My guess it's a mid to high 12 second car now that it has a 8.75 w/ 3.23's hooking up.
Bigger cam, more converter, more gear... quit being a sissy and put a 650+ DP carb on it.
With that gear, you sort of run it like a glide. 3000 stall would be fine. In fact, that gear will work the converter harder!
ALL carbs will require tuning to run best.
Fuel economy suffers with DP carbs is a load of trash. Kyles Demon with a 360, XE268H, small valve J's, LD340, 750DP, 2.94 gears and a 2500 hughes converter got 20mpg on the highway and around 15 in town as long as you drove it like a sane person. Fuel economy is DIRECTLY related to your right foot!
That Demon ran 14.00 at 104+ mph in vegas with a rotten 2.25+ 60' and a fat tune up because the air was 4500+. It was babied out of the hole because of the 7.25 pegleg rear. It wasn't full throttle until about 80-100' out. My guess it's a mid to high 12 second car now that it has a 8.75 w/ 3.23's hooking up.
Bigger cam, more converter, more gear... quit being a sissy and put a 650+ DP carb on it.
If you're going to race it, I would definitely start with a Holley (Proform, Quick Fuel, etc) 750dp. Like 70aarcuda said, take a look around at the track...unless it is a rules restricted application, 99% of the cars will have a Holley style carb. This is not by chance, its because they just make more power.
Completely off topic, which track do you race at in Indiana? I race Lucas Oil Raceway most of the summer (and a few other tracks)...just curious
Completely off topic, which track do you race at in Indiana? I race Lucas Oil Raceway most of the summer (and a few other tracks)...just curious
For the Strip 750 cfm. Street and strip. 650 cfm as stated . But for 4 corner idle circuit with that cam so you can idle off the secondaries and not be into the transfer ports on the primaries. It will be a little snappier and you will not have to bring the rpm's up to launch. You would be able to just stab the throttle from an idle and not get that little hesitation.
You want it to run it's best at the track put a DP carb on it.
With that gear, you sort of run it like a glide. 3000 stall would be fine. In fact, that gear will work the converter harder!
ALL carbs will require tuning to run best.
Fuel economy suffers with DP carbs is a load of trash. Kyles Demon with a 360, XE268H, small valve J's, LD340, 750DP, 2.94 gears and a 2500 hughes converter got 20mpg on the highway and around 15 in town as long as you drove it like a sane person. Fuel economy is DIRECTLY related to your right foot!
That Demon ran 14.00 at 104+ mph in vegas with a rotten 2.25+ 60' and a fat tune up because the air was 4500+. It was babied out of the hole because of the 7.25 pegleg rear. It wasn't full throttle until about 80-100' out. My guess it's a mid to high 12 second car now that it has a 8.75 w/ 3.23's hooking up.
Bigger cam, more converter, more gear... quit being a sissy and put a 650+ DP carb on it.
Are you allowed to call people Sissies these days?
ALL carbs will require tuning to run best.
Fuel economy is DIRECTLY related to your right foot!
quit being a sissy and put a 650+ DP carb on it.
LOL, LOVE this guy!
Mileage from the carb is tuning of the idle and primary circuit. This should be known to all.
Then your right foot is the next in charge of mileage.
Ya, you can, except if your a overly sensitive sissy being hurt by a stranger on the inter-net or the school bus.
If you're going to race it, I would definitely start with a Holley (Proform, Quick Fuel, etc) 750dp. Like 70aarcuda said, take a look around at the track...unless it is a rules restricted application, 99% of the cars will have a Holley style carb. This is not by chance, its because they just make more power.
Completely off topic, which track do you race at in Indiana? I race Lucas Oil Raceway most of the summer (and a few other tracks)...just curious
I race at the Terre Haute track theres only one here and no carb restriction. I have raced at Lucas also but I was in a ls1 maro lol... I might buy a carb tomorrow because its used and 150 bucks.. Its a 750 Holley vaccum secondaries . I just want to get the car running and get everything checked out since its been sitting a long time . I dont wanna spend a lot right now until I know where the car stands. Most likely I will change gears in the future but only to 3.55 because I wanna keep it for cruises . May build a stroker in the future.
LXguy
Well-Known Member
Hey:
I run a 670 street avenger as my cruise/ light strip carburetor.
Its plenty for your motor. My car has run 11s in the quarter with that carb. It is great for the street also. Very responsive, quick to start. My combo needed a 35 squirter and up a couple of jet sizes for peak performance.
I have an approximately 3500 stall converter and it works fine with this carb.
I prefer slicks to drag radials for consistency. Drag radials are capable of the same 60' times as slicks *but* they are much fussier about track surface. Also, they are harder on driveline parts than a slick.
Terre Haute is a great track. It hooks well so you might be able to get a drag radial to work. On my 71 Dart I run either a MT 255/60/15 or a Hoosier 26*8.5 stiffwall slick. I run a 15*8 wheel with 5.5 backspace (I run Pro Stars, but anything should work). I do have to run a 3/8 spacer for peace of mind.
My car has been 1.5 60' lots of times.
If you end up needing a spacer, let me know and I can show you which to get.
Good luck!
Steve
Thanks for all the info but I just home after being gone all day. I already bought the carb it was off a running 73 360 duster so I knew it was good. Its a 750 vacuum secondaries . The car I bought hadnt run in a long time I guess and I bolted it on and checked everything out and the car fired right up and smoked for a bit because of old fuel in fuel cell. Once the old fuel was out I put new 93 octane in and the car runs and sounds awesome. Idles great for the cam it has .484 purple shaft with headers and flowmasters that drop just in front of rear axle. When I rev it , it doesnt hesitate at all so I think it will be great. Im kinda interested in what the car will run, only downside is the 3.23 gears I would like 3.91 but dont have the cash right now. The car has no interior right now besides a drag seat and dash. Im gonna keep it a street strip car. It has coil overs and a four link also. Bad thing is that it has the small bolt pattern axles all the way around and Im not changing it yet because I wanna be able to race come . spring. Since I dont have leaf springs I wander what size slick I can go with with what backspace. I wanna keep the height down so I dont lose what little gear i have. I seen some 26x8x14 slicks. So what do ya think. Thanks Clint... Oh I hope it will run at least 8.5 to 8.9 1/8 mile.. I think it should.
harleydartguy
Dana R
I used that on a mild 360 68/73 jets 298.16 hp @ 5200 355.4 lbft@ 3300
Update on this thread I got a good deal on some MT drag slicks on some 14x7 magnum 500 wheels. The slicks are 26x8.5 and I also since changed gears from 3.23 to 3.91 and I took car for a little back road spin and I could really feel the difference so I should be a bit quicker at the track but I havent been there yet. I almost got her ready but need to get a driveshaft loop. What times do you guys think it will run. Its a 69 340 .30 over with flat top piston and j heads stock. It has a air gap intake , headers flow masters with h pipe that drop by rear seat , 750 holley vacumm secondaries , 3.91 gears 26 inch slicks and car only has two front seats no other interior. Its 1/8 mile track
harleydartguy
Dana R
Not familiar with 1/8 mile times, I would think that combo should get you in the 12's 1/4 mile. My nephew had a similar combo in a challenger and he ran 12.5's. (he now runs 10's after extensive engine mods.)
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