340 6 pack vs 4bbl intake

[randy73]

I just go offered first dibs on a 6 pack intake, I know one of the disadvantages of the 6 pack is tuning them. Other than that, what are the advantages and disadvantages of the 6 pack vs 4bbl on a 340.

[Mopar Nut]

Here's a good article

http://www.hotrod.com/articles/bad-mopars-340-beat-ford-chevy-shocking-new-data/

[BSB67]

This is why I hate magazine articles.  In this article they don't even make it past the first sentence without being full of crap.

[BSB67]

I just go offered first dibs on a 6 pack intake, I know one of the disadvantages of the 6 pack is tuning them. Other than that, what are the advantages and disadvantages of the 6 pack vs 4bbl on a 340.

If you are a tuner, htere is no disadvantage to the 6 bbl other than the cost for admission.  The performance benefit is not a much as with the big block.

[randy73]

Here's a good article

http://www.hotrod.com/articles/bad-mopars-340-beat-ford-chevy-shocking-new-data/

They put a 600cfm 4bbl on the setup, according to all the information I have been able to gather, the minimum should have been a 675 carb going by Holley's chart and what I read. Seems like they staved it with the 4 bbl to make the 6 pack look better.

[Troy]

Is the engine stock or modified? How do you plan on using the car? I only have one 340 car right now and it doesn't run. It's a 4 bbl. I've had several small blocks with 2 bbl carbs and one with a 4 bbl Edelbrock. I have had big blocks with Edelbrock and Holley 4 bbls and, currently, one 440 with a Six Pack. Let me clarify that I am not an expert tuner! All my cars with a 2 bbl just work. Even when I had a 2 bbl on my 351 Mach 1, it started, drove, and had plenty of power without ever really touching the carb (it's a BIG carb). It's possible that the sheer lack of adjustability helped in that you couldn't really get it too far off). I had a 440 with an Edelbrock that was easy to "get close" but hardly ever ran perfect. This may have been the fact that it used metering rods and/or the fact that they don't seem to have minute adjustability. After that I learned more about carb tuning and, well, knowledge is power. I have a Holley 4 bbl double pumper with 4 corner idle now so it has lots of room to screw things up! Add in the Six Pack on the other car and life can get difficult! I fought with the Six Pack for several summers. It would run hot, boil all the gas, then get plugged up. Or idle super rich but the go lean at WOT. Or be rich at WOT but ping at part throttle. Fun times! Since I am not a super mechanic I am not good at reading plugs and all the other tricks (plus yanking plugs on a hot 440 in a small engine compartment really sucks). I have rebuilt the carbs twice in 4 years, put on all the parts listed in the "tuning guide", ripped all the parts back out, tried several combinations of vacuum pod springs, replaced all vacuum hoses and fuel lines (twice as the design and aftermarket parts are a nightmare), and tried at least 4 different power valves. Probably my worst mistake was fighting an ignition problem at the same time. Get the ignition right first! What finally got me over the hump was buying a wideband O2 sensor. I can see the effect of every adjustment on a digital readout. I also purchased some of those snazzy idle screws that let you adjust the rear carb without removing it. Well worth the cost!!! I think I had it running smoothly less than 2 hours. That was last fall. I hopped in it this year under the same weather conditions and it's not the same. It still runs well but the numbers have shifted. Then, when the weather got 20 degrees warmer it had a fairly drastic effect. So, even though it seems to be set up and happy it still requires a regular amount of fiddling. The Holley 4 bbl is about the same with fewer things to worry about - well, except you have replaceable jets instead of metering plates so maybe it's not really any simpler.

And that is why I have 2 EFI setups for the next cars in line. I like to drive - not mess with something that I feel should just work. As I get older I get less tolerant of things that are frustrating.

Soooooo, if you're reasonably good at tuning a 4 bbl and understand how everything works together it's probably not a big step up from a good 4 bbl. If you're a novice you'll have a steep learning curve - but similar if you're going to a race inspired 4 bbl. I can tell you that mashing the pedal and hearing that sound is a wonderful experience! Unless you have something off and it balloons your mufflers...

Troy

[randy73]

Thanks, think I will stick with the 4bbl. One day I would like to go EFI, but right now all my extra funds are going into my engine and paint job.

[303 Mopar]

Thanks, think I will stick with the 4bbl. One day I would like to go EFI, but right now all my extra funds are going into my engine and paint job.

Good call.  I had a 340 6-bbl on my Cuda and it was a PITA to keep tuned, which is why it now has a 392 Hemi.  My Charger has a 4 bbl and Sport Satty convertible has a 2 bbl.  More simple and easy to track down issues and adjustments.  I will probably go Fi-Tech EFI on the Charger within the next year or 2, but the Sport Satty will stay 2 bbl because it is all original.