best carb for 340?

[RiceHater]

Hi have a 72 challenger with a '70 340. it has some work done to it.  340 engine bored 40 over, alum heads, crane cam, JE pistons, edelbrock torker 2 intake, old blackjack full length headers, magnaflow 2.5" SS x pipe and catback. all connected to a 727 3 speed slap stick auto w/ reverse valve body and shift kit. it had a holley 750, electric choke, 4 barrel carb on it and it used to stall a lot. i replaced it with the same exact carb about 5 years ago. with the new carb i got it to idle at 900rpm in gear but it would still stall out sometimes when I come to a full stop unless i give it some gas.

this holley 750 4 barrel carb sucks. please recommend the best carb for my application. some have said that the 750 is too big and a 650 would be better. any thoughts? what are some good brands? any specific carbs work well here?

[crazy larry]

I like thermo quads my self. But I to am in the hunt for a new carb for my 360. I will be watching this thread.

[Hot_Rodder]

I can tell you now, everyone has a favorite carb manufacturer...... Some love Holley's and that's about it.... Some are Edelbrock only.... some are Quadrajet people.... ect ect ect.... I had a Holley #3310 with electric choke conversion, hate it... Don't want another. Now, this was on a 440.... Now for your 340, a 650/700 cfm would probably be ok.... Now as for my choice in carbs, I have not ran them all, but I have ran a worn out (not my fault it was worn out, it came on the car when I got it....) Carter AVS, Holley #3310 (brand new, never right), and a Street Demon 750 cfm with vacuum secondaries and electric choke.... I didn't have any problems with the Demon, but then again, some people here have.... My vote is gonna have to go toward the Demon. There's my  . Now it's time to sit back and: 

[Chryco Psycho]

Holley 750 HP street series #82751

[Carlwalski]

650 Speed Demon

[dimples]

Edelbrock 750 performer. 

A good cross between the thermoquad, and a holley.

[72hemi]

Go with the 650 or a 670 Demon. I'm running 2 carter 600's on my 340 and it looks cool, but is way too much gas.

[RedLine]

On our 383 we first had a 650 Holley, then a 750 Eddy, (both fine, but not exceptional) then we went to 650 Street Demon.  Huge low end torque.  but we had a stumble in the primary to secondary transition.  Chryco tuned that problem out of it. ( It then ran the best it had ever run.)  but the NEW Holley Street HP Series 750's are out now that compete with the Demons for quality.   

So we put one of those on.  Less torque off the light- but smoother transitions from 0- 100 mph.  But if you want raw torque in the lower rpm's - for us the 650 Demon had the edge. (if tuned right!)  But 650 was really too small for our bored 383.  we swapped that for the more well behaved new Holley.  We have our Street Demon 650 up for sale if interested

[Aussie Challenger]

  As stated above everybody has a favourite carby, some manufacturers put slow closers on their carbies for this very reason. If you backed off quickly especially on an automatic car it would just stall. A slow closer is just a little diaphram which slows the throttle linkage coming back to idle a little. I have fitted these to some wild engines but you must be carefull that they don't cause your engine to run on when shut down.

[rallyechall]

What do you do with the car? Is it a cruiser, street strip, or more just for racing? Any carb, as long as it is of proper size for your motor, will be fine. Ninety percent of all carb problems are due to the owners overcarbbing, or not knowing how to adjust the carb correctly. Carter does not measure CFM the same way that Holley does. That is why a 800 Thermoquad is standard on a 340, but a Holley 650 will run as well. Whatever you decide, be sure to purchase a manual  before your carb to familiarize yourself with the product. SA Design has great reference books, and teach you to rebuild maintain, modify and tune your carb. Don't treat it as a crap shoot. Arm yourself with information so you are confident and content with your purchase.

My Choice: Carter Thermoquad. Small primaries great off the line. Big Secondaries, awesome kick when secondaries open.   Decent gas mileage espcially with today's prices. You just can't beat that throaty thermoquad sound when the secondaries kick.

[crcarch]

My Choice: Carter Thermoquad. Small primaries great off the line. Big Secondaries, awesome kick when secondaries open.   Decent gas mileage espcially with today's prices. You just can't beat that throaty thermoquad sound when the secondaries kick.

Love the TQ but I always found them a bit touchy in keeping tuned.  I swapped a Holley 650 DP on my 340 and it was very responsive.  Not as economical as the TQ and didn't have that sound when the secondaries kicked-in, but it ran very well with a decent cam and headers and had awesome throttle response.

[Chryco Psycho]

actually all 4bbls are supposed to be rated based on 1.5" of vacuum but the new holleys & Demons are wet flowed & yes a 340 will use 850 cfm if it is controlled properly with vacuum , remember the 6 pack is even bigger than  the 850 TQ

[GhettoPop]

i started this thread as ricehater...i finally got my old udername back!  anyways, i took out the holley 4 barrel 750 elec choke, vac secondaries (80508S) that i had in there. even brand new out of the box that carb was never great. (as someone mentioned above). i picked up an edelbrock performer 600 elec choke, mech secondaries.

 i felt it was the best carb for me. the car will be driven around cruisin to shows and a little street fun and games. no heavy track use. the info i got suggested this edelbrock 600 will make be like night and day and the car will drive better all around and respond much quicker. i won't really lose any power and significantly reduce fuel consumption.

any thoughts?

i also read someplace that this carb is "not recommended" for the torker II intake, which i have. any info ??

[moparnut]

Edelbrock 750 performer. 

A good cross between the thermoquad, and a holley.

[PaxtonPwr]

The holley street avenger carbs are our most popular, easy to tune (most time out the box only a float adjustment is needed when properly sized)  670 is good for the average street machine, or the 770 works well with SB's that are modestly worked (350-430hp) or mild BB's or step up to the 870 for the 'grunt' 'grunt' more manly motors