750 Holley or 650 Holley DP carb for 340-4 speed?

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1971 Duster

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Hey Guys,

I have a 72 Demon with a 340 4 spd (a833). J heads, Edelbrock Performer,
cam is unknown, but choppy. Headers with 8 3/4 rear end and 3:55 gears.

The car will be run at the track most of the time, some street use.

A very knowledgeable friend recommemded that I change my current setup (Holley 3310-2 750) to a Holley 4777 650 DP, with mechanical secondaries and manual choke. He mentioned it would be a better choice since I'm runnimg a 4 speed and will be making passes at the track.

I know carbs can be personal, jiust wanted to hear from the members on their ideas before I do this.

Thanks Guys!
 
My 340 4-speed loves my Holley 650 DP carb, I am running a M1 intake and 1" super sucker carb spacer, Hooker super comps and 4.10 gears :burnout:
 
Thanks 66340Sedan!

I know there are some happy folks with their 750's, but my friend said the 650 is more than capable for my mild setup.

However, if a 750 is the way to go, I'm listening!
 
1971 Duster said:
Thanks 66340Sedan!

I know there are some happy folks with their 750's, but my friend said the 650 is more than capable for my mild setup.

However, if a 750 is the way to go, I'm listening!
Click to expand...

I have seen 650 DP carbs on all types of 340's from stock to wild and all seem to work great :burnout:

I would however like to try a larger carb someday, my 340 winds up fast and pulls hard right to the rev limiter...but it works so damn nice its hard to pull it off :glasses7:
 
If I go with a Holley 750, which model number do I need? DP version, mechanical secondaries? I'm new to the 340 so specifixs would really help me make make the right choice?

Yes, I will be at the track most of the time. Occasional street time, limited.
 
With a 650 ish,, it'll run great,, with a 750ish , it'll run awesome..

You can pick up a #3310, a 750/780 Holley at any swap meet for less than $100,, kit it, and luv it..

What you'll find is a lotta folks have fine running vehicles with a 600/650 carb,, cuz they run great,, but they've never tried a 750ish ,, so frankly can't compare,,

What you gotta do is find a buncha folks saying they took off the 750 cuz it was too ???.. and put on a smaller carb,, and there won't be many... and those folks that did,, would be looking for gas mileage, not power..

I've replaced 3 - 650s with 3310s in the last year,, and the owner's grins said it all,,

not one of them wanted the old carb put back on..
 
Really splitting hairs here imo? I could make all 3 of them work on that combo. If you really want a DP, and it "will" make your midrange feel stronger, I'd just go with a 750. That size is just too easily used on many combos you may change to over the years. I'm old school, so I'd just grab a List #4779 and be done with it, but there are some fancier models out there now days.....if you want to spend the extra coin?
 
inertia said:
With a 650 ish,, it'll run great,, with a 750ish , it'll run awesome..

You can pick up a #3310, a 750/780 Holley at any swap meet for less than $100,, kit it, and luv it..

What you'll find is a lotta folks have fine running vehicles with a 600/650 carb,, cuz they run great,, but they've never tried a 750ish ,, so frankly can't compare,,

What you gotta do is find a buncha folks saying they took off the 750 cuz it was too ???.. and put on a smaller carb,, and there won't be many... and those folks that did,, would be looking for gas mileage, not power..

I've replaced 3 - 650s with 3310s in the last year,, and the owner's grins said it all,,

not one of them wanted the old carb put back on..
Click to expand...

That's great info,thanks.
My 70 Duster with a built 340,4 speed and 3:91s came with a 750 DP and I thought it might be a bit too much carb for a small block.I ran across a barely used 650 DP and picked it up for future use but I think I'll stick with the 750 now .:burnout:
 
I tried a 650 DP on my 340. Ran great. But went back to the 750 DP. It ran slower at the track with the 650. The 750 had more power. Don't remember the time difference though. Both carbs were tuned for the combo to.

Fred B
 
Since its mostly track i have one question, will you be lifting in between shifts or power shifting? if lifting i would go with a 650 or 700 DP, if power vacuum sec 750 will be fine. i would also stick a 3.91 or 4.10 gear in it to make that small block bogie.
 
I have had both Holley 650 and 750 DP on my 69 340 4 gear swinger with 3:55s. I always end up with the 750 back on there. Seems to give it a little more top end. The 650 was nice and crisp as well. Either is a good choice. If you are going to race it Id go 750
 
I am running a 700 dp on my 340, it is a 4-speed and I switch out between 3.23 and 4.30 gears depending on how I am driving it.
Any of the carbs suggested will work, including the one you have right now, a 3310 is a very nice carb.
 
Very helpful info!

Thank You.

Looks like I'll just rebuild my 3310-2 and make the most of it.

Yes, I will be adding a Hurst Vertigate shifter so I can power/bang shift!
 
I would go with the 4779 Holley 750 Double Pumper.....but know the 750's with the 4779 stamped choke horn.....get pricey.

In a pinch or on a budget....I would buy a swap meet/ebay/fabo 4777 650 Double Pumper....for $100-$250 and put a ProForm 4777 Main body on it with No Choke provisions, and rebuild the carb with Nitrophyl Floats....and 72 Primary Jets and 76 Secondary Jets and 6.5PV and be done with it for about $240.00

The difference is better than just seat of the pants........even with an Auto.
 
1971 Duster said:
Very helpful info!

Thank You.

Looks like I'll just rebuild my 3310-2 and make the most of it.

Yes, I will be adding a Hurst Vertigate shifter so I can power/bang shift!
...
That is what I'll do, and just put the 3310-2 on the shelf.

Thanks Guys!
Click to expand...
Pretty funny. As you can tell, a query like this will provide you with three points of view.
It really depends on what your engine wants. The smaller venturies and throttles will generally help bottom (street). They may help throughout the range when fuel distribution is not ideal or the engine really likes a bit more atomization of the fuel.

The 3310-2 is about as good as you can get for a vac secondary 4150. I'd spend time tuning that before trying another carb. If its unmolested, jet and spring changes are about all it should need.
 
I tell you what Iv tried.Ive tried and tuned them all on my 360/430hp/A833.Also ran a TQ.Also ran a 2bbl. Also ran a 600Vac. Every single one worked great on the street. But for me, when I punch it, I want stuff to happen right now. I want the 295s howling. I want; smoke, a screaming engine and a roaring intake. And I want it right now.I cant wait for the V-secondaries to open. The DPs are as close to instant as you are likely to get. The small one might be a hair quicker at lower rpms. But the bigger one? now thats something.It lets those ponies run.
On the street, typically, its a lot of posturing.When you hit it, or at least when I do; its all over in 2 or 3 seconds.Its usually in 2nd gear.And speeds are usually well below 30 mph.So the DP gets it done.
-Should add; I have run the 750DP with nearly every gear from 2.76 to 5.13, and with cams from 223* to 240*
-So,my experience is all street.I cant say about the track.The little track experience that I do have: With the V-secondaries I could launch at a higher rpm and with more throttle, and just let the carb do its thing. With the DP, I had to kinda baby it out, or else lose it all to tire spin. If you can hook,shift and drive, Id go DP. And leave the little one at home. Just my 2 cents.
 
hi 71 duster..

45 years ago, the head mechanic at my local plymouth dealer ordered a new 68 fastback formula s 340 4 sp. he immediately installed hooker fender well headers, the "latest" edlebroc alluminum high rise manifold, a holley 750 dp with mechanical secondaries and a 3:91 gear. that car turned consistent low to mid 12s in the 1/4 with open headers and slicks. i managed to buy that car from him after he had it about a year and i never lost a street race against anything with that car.

so ... i have a very simple opinion: 340 motor; headers; edelbroc high rise manifold; holley 750 dp with mechanical secondaries; 3:91 diff - that's all you need.

one other point that you may or may not care about. when you bury your foot into the firewall with a 750 dp holley sitting on a 340, that loud screaming sound you hear not only comes from your 340 but also from that carb. i NEVER get tired of doing this as that sound always makes me wonder if the hood is going to get sucked into that holley carb. along with that frightening mopar scream comes that sudden 750 whiplash jerk as a result of the mechnical secondaries instantly dumping half your gas tank into that "semi-hemi" 340. i get a kick out of that too....
 
And I agree, for track work, more gear. Depending on your cam/redline, the 3.55s might get you to the finish line with just 3 gears or a possible shift just before the line. Not the best for ETs.If you want to ET well you will need all 4 gears, and be lightning fast on the shifts. A 4.10/4.30 will get you close, but DO THE MATH.
-AS an aside, Jim, I hear you on the screaming intake. I remember the TQs. That part throttle-moan at secondary tip-in is unmistakeable. I loved the sound of my L/C 360 TQ trying to pull through the A/T and 2.76s from 2200rpm, in my 71 Monaco.I could never find it in my H/C 360M/T, S-clone. It just built rpm too fast.
 
66340SEDAN said:
My 340 4-speed loves my Holley 650 DP carb, I am running a M1 intake and 1" super sucker carb spacer, Hooker super comps and 4.10 gears :burnout:
Click to expand...

what 1/4's you getting with that set up

love the M1 intake but its killing me on the 60' compared to weiand xelerator
(but thats not as hard as the M1 after the 1/8th)
 
I think this is a "run what you got" kinda thing, but that's just me.
 
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