Im building a pretty much stock 340 with x heads, im wondering my best bet for carb will be? The motor is pretty much stock, with comp thumpr cam, doug headers, tti exhaust. A friend suggested i use a 750 cfm 4150 holley.What are your thoughts on this?
best carb for 340?
- Thread starter 19scamp72
- Start date
-
I think the Thunder series Edelbrock AVS would be good. A 650 on that would be tough to beat.
tekslk
Well-Known Member
Holley 670-77 street avenger. You will like them.
swinger340
Well-Known Member
Holley 4150 650 or edelbrock 750 thunder series. JMO a couple carbs that have worked great for me in the past
No matter what brand you get it is all in the tune.
You did not state which thumper cam, gear ratio, stall of the converter and what YOU will be doing with the car. These items have a impact on carb size. While a 750 could be a very streetable carb, it could be a tad big and the smaller 650 would be better. Look at it this way;
The 650 carb will work best when you have a low numerical gear ratio, small cam and you want excellent throttle response for the street.
The larger carb works better with a numerically high gear ratio, stall speed and bigger cams. The 750 favors a higher top end power and speed.
This is not to say a 750 will not work in place of a 650. Throttle response will go down a little along with mileage and best running conditions.
On the flip side, this is also not to say a 650 carb will not perform well where a 750 performs best. The top end power will only be down a few HP.
IMO, iF you choose a Edelbrock carb, I would use the AVS Thunder style carb.
The Holley 4150 is best suited for numerically higher gear ratios, higher stall speed, larger cams and manual transmissions. A vacuum secondary Holley would be better suited for most driving conditions and light racing.
Like above, this is not to say the carbs styles can not be swapped to and made to work well in each other's spot.
If your going to make a driver out of this car, use the smaller 650 carb in a vacuum secondary style. You'll be happier in the long run and down only a few HP on the top end of the rpm scale where you rarely are.
You did not state which thumper cam, gear ratio, stall of the converter and what YOU will be doing with the car. These items have a impact on carb size. While a 750 could be a very streetable carb, it could be a tad big and the smaller 650 would be better. Look at it this way;
The 650 carb will work best when you have a low numerical gear ratio, small cam and you want excellent throttle response for the street.
The larger carb works better with a numerically high gear ratio, stall speed and bigger cams. The 750 favors a higher top end power and speed.
This is not to say a 750 will not work in place of a 650. Throttle response will go down a little along with mileage and best running conditions.
On the flip side, this is also not to say a 650 carb will not perform well where a 750 performs best. The top end power will only be down a few HP.
IMO, iF you choose a Edelbrock carb, I would use the AVS Thunder style carb.
The Holley 4150 is best suited for numerically higher gear ratios, higher stall speed, larger cams and manual transmissions. A vacuum secondary Holley would be better suited for most driving conditions and light racing.
Like above, this is not to say the carbs styles can not be swapped to and made to work well in each other's spot.
If your going to make a driver out of this car, use the smaller 650 carb in a vacuum secondary style. You'll be happier in the long run and down only a few HP on the top end of the rpm scale where you rarely are.
65-440
Well-Known Member
I'm running a Holley 770 Street Avenger on my 340. Stock bore, Eddy heads & intake, .488" lift cam, Full 2.5" TTI exhaust, 4spd w/3.55's .... I have been contemplating trying a smaller carb to see how it performs .. The car runs GOOD now, but curious if a smaller cfm carb will help or hurt..
I had a mild 360 (.484 lift, 340 J heads, headers) and 3.91 gears. I took 2 carbs to the drag strip. A 750 dp Holley and a 625 Carter. The 750 ran almost 2 tenths faster and a little over 1 mph. The 625 did cut the same 60 ft time.
EL5DEMON340
Well-Known Member
650 DP Holley
SleeperScamp
Well-Known Member
How would a Thermoquad compare to the others mentioned here???
DaveBonds
Garage Trash
The same. The TQ is a good carb, you just have to play with jetting. They lend a better throttle response than other higher CFM carbs on an engine that size, because of the small primaries. Not very good race carbs, IMO, compared to a DP but excellent on the street.
Rumble is right on the money, with the tune.
I used a Street Demon, same idea, new components, so you can get jets and rods easier. It has a nicer idle system with the sandwiched baseplate gaskets and the thin, metal spacer that it comes with, in conjunction with two bleed holes at the front of the primaries, that redirect air to the center of the intake plenum to help idle and transition stability in RPM. It certainly does what it's designed to do. I was able to trim 30rpm on my digital tach from the idle with that carb.
I'm using the 625 on my 318. They do make a bigger one. The AVS that rob suggested would be very similar, but the primaries are a little larger and it has smaller secondaries. More of a square size. the Street Demon acts like a TQ, but is on a square bore intake pattern, unlike the Rochester and Carter carbs. Accomplishes the larger secondary flow like the TQ, with a unified secondary throttle plate they call a goggle valve. They did that for the same reason they did the air bleed at the primary, to help redirect air to the center of the intake plenum.
Rumble is right on the money, with the tune.
I used a Street Demon, same idea, new components, so you can get jets and rods easier. It has a nicer idle system with the sandwiched baseplate gaskets and the thin, metal spacer that it comes with, in conjunction with two bleed holes at the front of the primaries, that redirect air to the center of the intake plenum to help idle and transition stability in RPM. It certainly does what it's designed to do. I was able to trim 30rpm on my digital tach from the idle with that carb.
I'm using the 625 on my 318. They do make a bigger one. The AVS that rob suggested would be very similar, but the primaries are a little larger and it has smaller secondaries. More of a square size. the Street Demon acts like a TQ, but is on a square bore intake pattern, unlike the Rochester and Carter carbs. Accomplishes the larger secondary flow like the TQ, with a unified secondary throttle plate they call a goggle valve. They did that for the same reason they did the air bleed at the primary, to help redirect air to the center of the intake plenum.
65-440
Well-Known Member
They are if you know what your doing ! A buddy of mine won't touch a holley. His dad got him into racing Mopars back in the late '70s, only ran TQ's. He has a small book of all his trial and errors with measurements and different mods w/ each end result. His Demon was a 10.0 car with a TQ, everyone thought he was full of **** until he opened the hood. One time he took a Dominator with him, swapped it out during test n tune and ran slower... now it sits on a shelf collecting dust ! I borrowed one of his TQ's for my '65 Coronet, I did not wanna give it back. It drove like a fuel injected car around town, very crisp. And hold on when you stomp it ... def was best of both worlds, was a very good carb !
NHRA Class racers with 71 and new mopars...HAVE to run the TQ in Stock and Super Stock...alot of fast cars running them....their are a few people out there that knows how to make them run fast...For the average racer..a holley DP probably is easier to setup and tune....
for a basically stock 340...I would go with one of the eddy avs carbs..I have a eddy 1406 that is about 10 yrs old and never missed a beat on a stock 73 duster...only problem is the bowl going dry after a couple of day due to the lousy gas and accelerator pump well not being on the floor of the bowl.
for a basically stock 340...I would go with one of the eddy avs carbs..I have a eddy 1406 that is about 10 yrs old and never missed a beat on a stock 73 duster...only problem is the bowl going dry after a couple of day due to the lousy gas and accelerator pump well not being on the floor of the bowl.
DaveBonds
Garage Trash
Oh yeah. They can be quick. The '72 Dart junkyard 318 car was in the 14s up at Bandimere Speedway, well above a mile over sea level.
They take a little tuning and aren't as tune friendly, but I still love them.
This Demon that I have is like that too. You've got to get the carb off of the intake to change components, screws go in from the bottom, but once it's set, look out! Very throttle responsive and I've never had a carb idle as smooth as this one.
They are sophisticated for street use, which is where they really shine. I have another TQ on my shelf. It needs a resin body, but it's a good carb, otherwise. One day, I'm sure it will see use, likely in the '72 Duster.
You did not state which transmission you have but about any carb from 625-700 should run great on you combo.
The new Demon 625 works real smooth on my stock 318 truck, but for the 340 duster I am going to run a 700 DP with about the same motor combo as yours, but my car has a 4-speed and 4.30 gears.
Tune any of the above mentioned carbs, they will work.
The new Demon 625 works real smooth on my stock 318 truck, but for the 340 duster I am going to run a 700 DP with about the same motor combo as yours, but my car has a 4-speed and 4.30 gears.
Tune any of the above mentioned carbs, they will work.
skrews
Well-Known Member
670 Street Avenger
Someone mention that a TQ isn't a race carb?
This would be slightly incorrect since it was designed and developed as a race carb making its intro in NASCAR (IIRC) a few years before it was standard equipment on passenger cars. The smaller primary side is not a hinderance.
You do not want the first year TQ. Less emissions equipment on it the better for high performance useage.
Theres a few draw backs to a TQ. Rods can be made from AFB/AVS (Edelbrock) rods but jets, front and rear are not available. (Though *I think* someone is making the front jets.
The rebuilding of one, may require bushing the shafts. Break the main body, you could be SOL! The carbs centers do not readily swap with another. You must also use the correct gaskets for that carb you have.
And the last draw back is the huge secondary side which will require an adapter for square ore intakes. Unless you can carve up the intake to accept a TQ. The Weiand Stealth and Edelbrocks LD340 can be cut up to take a TQ.
What is nice though is that the Edelbrock performer, the Action plus and MoPars M1 single plane will take a TQ on no problem. Also the seldom seen Offenhauser Port-O-Sonic can take a TQ, IF it is the right Intake. The do come with a square bore as well. Excellent intake with MoPars mods!
This would be slightly incorrect since it was designed and developed as a race carb making its intro in NASCAR (IIRC) a few years before it was standard equipment on passenger cars. The smaller primary side is not a hinderance.
You do not want the first year TQ. Less emissions equipment on it the better for high performance useage.
Theres a few draw backs to a TQ. Rods can be made from AFB/AVS (Edelbrock) rods but jets, front and rear are not available. (Though *I think* someone is making the front jets.
The rebuilding of one, may require bushing the shafts. Break the main body, you could be SOL! The carbs centers do not readily swap with another. You must also use the correct gaskets for that carb you have.
And the last draw back is the huge secondary side which will require an adapter for square ore intakes. Unless you can carve up the intake to accept a TQ. The Weiand Stealth and Edelbrocks LD340 can be cut up to take a TQ.
What is nice though is that the Edelbrock performer, the Action plus and MoPars M1 single plane will take a TQ on no problem. Also the seldom seen Offenhauser Port-O-Sonic can take a TQ, IF it is the right Intake. The do come with a square bore as well. Excellent intake with MoPars mods!
The shop I worked for,did a stock 74 440 4x4 Club Cab. The heads got yanked,replacement was well ported 915's. Threw a 440 Torker 2 ,at it(not my choice.). A came in the high 220's intake /230's exhaust. Tried my old 4779 750 Holley. Decent,not the best choice I know. He scrounged a early 750.T.q.. Did a basic kit,followed the Direct Connection manual(1973), for basic setup. Jesus, that thing got crisp for a 9-ish to 1 440. Got louder ,too. (Lol). Hammered hard,at the beach. They are neat,set up correctly. (Used a 2 inch spacer ,to fit Carb to manifold...).
The Thermoquad is excellent. Has a fairly steep learning curve. The Eddy AVS is the next best, IMO.
dartomotive
Well-Known Member
That's true. The good answers suggested are what works for the responder's application.
Its a 727 with 323 sure grip posi. With 2800 stall. I have a eldibrock 650 cfm if im correct pretty much new so im hoping i can use this and get away with Ok power with it...
Thanks for the help this forum has been so helpfull, im getting the info on the carb i have shortly as its not infront of me atm.
Yea no doubt! I made a mention to it earlier since the suggestions are good but lean to one side or another in terms of size carb and application and possible intended purpose of the car.
Technically I could recommend a 550 to an 850 and be right with the amount of info given so far.
This is the carb i have sitting at home. If.i can get away with using it without loosing numerous amounts of hp i will?
http://m.summitracing.com/parts/edl-1406
Only 600 cfm, what other info would you like to know about my car as i have already provided some in previous posts.
http://m.summitracing.com/parts/edl-1406
Only 600 cfm, what other info would you like to know about my car as i have already provided some in previous posts.
-
