Edelbrock LD340 WTH?!?!?

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wolfhammer

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Ok so today I did a little research on small block intakes, the famed LD340 to be exact. What's so special about them and why they supposedly out perform all others?
This is what I found, look at the runner design, the LD340 runners are at the opposing ports. They hit on all the opposite cylinders as all the others. Could that have been Vic Edelbrocks secret with the LD340? The intake port pulses are better that way? Why don't the others all try this to see what happens? I checked other manifolds and all are different from the LD340.

LD340 comparison to M1 and stock.JPG
 
They don't out perform all the others.

There's a bunch of old school hype about them.

The Edelbrock Air Gap outperforms it. And the Edelbrock RPM matches it.

But the LD340 will outperform those 3 other manifolds you have pictured. That's not saying much.

People get off on them because some have factory numbers. But that was just because Chrysler parts dept sold them over the counter. And the old DC Manual said to use them. But of course the Air Gap and RPM didn't exist then.
 
autoxcuda said:
They don't out perform all the others.

There's a bunch of old school hype about them.

The Edelbrock Air Gap outperforms it. And the Edelbrock RPM matches it.

But the LD340 will outperform those 3 other manifolds you have pictured. That's not saying much.

People get off on them because some have factory numbers. But that was just because Chrysler parts dept sold them over the counter. And the old DC Manual said to use them. But of course the Air Gap and RPM didn't exist then.
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I agree, all hype. I would never pay what some want for an old intake that could have been machined for decking or head milling then won't fit properly. I have seen them asking as much as $700 for one!!
 
The original LD340 was supposed to be an aluminum (light weight) version of the stock steel manifold.
The part#s on the manifolds and the Hooker under chassis headers made them NHRA acceptable, and like many, I bought mine from my Mopar dealer to maintain warranty .
The LD 340, Hookers, and 3310 were the first thing the 1970 Mopar Hustle Catalog recommended changing for performance.
 
Also pre emissions and looks better than the newer manifolds. Not as cool as an airgap but for the average street car that sees a strip now and then it’s a home run.
I’ve got 2 of them. Maybe I’ll sell them when it is tie to buy a lake house. lol!
 
Syleng1 said:
Also pre emissions and looks better than the newer manifolds. Not as cool as an airgap but for the average street car that sees a strip now and then it’s a home run.
I’ve got 2 of them. Maybe I’ll sell them when it is tie to buy a lake house. lol!
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RPM 7176 looks very similar. Just ports arrangement is flipped top to bottom.

Both seem to have the same amount of stock resemblance to me.

1706125354881.png
 
Hype in the same way the 280/280 purple shaft or XE268 cams are done. Someone built one that worked well 25+ years ago so that's the only thing that people follow.

My opinion the Weiland manifold looks the closest to the LD340.

I did EFI and switched from an air gap which worked well to a Super Victor EFI and honestly I think it has better low end than it did before even with a "3000-7500 rpm" manifold. Can literally pull a hill at 1400 rpm in 6th very easily with that manifold and a 227/231 duration at 0.050 .530 lift on a 110 hydraulic roller. With a carb its different but if you don't want an exhaust crossover, just buy an air gap.
 
Performance aside, the LD is one of the prettiest manifolds for it's day. If only Mopar would have contracted it for the 340 production line like Chebby did with the Winters foundry for their performance engines.
 
They were about the best for a dual plane intake back in the day and better than a lot of the single planes without giving up anything on the bottom end. They are also as good as some modern intakes....but as mentioned, they are far from outflowing "everything out there". They are very good intakes though.
 
The LD340 is a great manifold especially for the street car. I don't think that the difference between high or low runners was done for performance reasons. The first intake that I ever bought was an LD-4B (1975). It was the 273/318 version of the manifold (I think first produced in 1964) and it has the runners in the other configuration.. It is also a great manifold. When I went to reinstall the AC compressor on my 1970 318 after the manifold swap, it wouldn't fit because the front runner that was high, was in the way. An LD340 (first produced in 1968) with the high runner on the other side works fine with factory air. I always made the assumption that this was the reason for the change.
 
I'm not sure what the point of this thread is other than to split hairs. Each engine build is individual in its needs and characteristics.

I run an LD340 and my old man has an LD-4B on his car. Both work well, and both were cheaper to buy than an equivalent(ish) new manifold, and a hell of a lot of 2nd hand manifolds. It's a comfort having a piece of history bolted in there too.
 
I like mine and it runs better than without it
IMG_0207.jpeg


IMG_0203.jpeg


For me it’s a requirement because for right now this is a day 2 build. I enjoy the fact that it’s lighter than the OE 340 intake, it’s period correct, and it was cheaper than a new intake at Summit
 
autoxcuda said:
RPM 7176 looks very similar. Just ports arrangement is flipped top to bottom.

Both seem to have the same amount of stock resemblance to me.

View attachment 1716196945
Click to expand...
Okay but that intake is almost $500 new.
LD-340s typically are like $300 used.
What is the cost used going for? I’ve not priced them used. But I bet it is close.
 
So I just used the search feature and they typically sell used on this board for $290-$375 used. For that much money I would wait for an LD-340 intake all day long.
 
wolfhammer said:
Ok so today I did a little research on small block intakes, the famed LD340 to be exact. What's so special about them and why they supposedly out perform all others?
This is what I found, look at the runner design, the LD340 runners are at the opposing ports. They hit on all the opposite cylinders as all the others. Could that have been Vic Edelbrocks secret with the LD340? The intake port pulses are better that way? Why don't the others all try this to see what happens? I checked other manifolds and all are different from the LD340.
Click to expand...

The LD-340 has larger more free flowing runners. This is key to making power. The other intakes you have posted are just simply stock parts. The OEM parts are made and designed to be the best they can be under a heavy limitation imposed by the factory design engineering department for a slew of reasons. Long life, compact design for under the hood clearances in anything they build today(when it was new) to whatever they may build for tomorrow and warranty.

The aftermarket is free to do what they wish without worry of local, state & federal laws. So the material changes, iron to aluminum, designed for more power without care or concern to emissions, hood clearance, other parts fitting or clearing like A/C compressors.

There goal is to just make a part that makes more power. Screw everything else. This free’s up there design to be what ever they come up with.

I had a LD-340, did the MP mods, it was a good unit for sure. As said above, the modern designs are better. They should be considering the time the LD-340 was made and when the RPM AG was made. As time passes, the new part should and better be a more powerful part.

I wouldn’t pay a hefty price for an old intake. IMO, it better be a good bunch cheaper than a new intake. There are a lot of pipe dreamers that are disillusioned and think “I have MoPar GOLD here and I’m going to get a kings ransom for it!” If it’s the last one on earth and some fool “NEEDS” it, you’ll get the ransom I’m sure. Otherwise, a fool and his money are easily parted.

I’m all for a guy saving a buck and such. An excellent second place intake manifold is just as good when the absolute max is t needed for what ever your doing. An excellent example is a Weiand intake. It’ll make really good power for a whole bunch cheaper.

I’ve seen so many guys go out and get the best of everything, surrender tons of money and get whipped bad, really bad by a guy that got ridiculed for have second rate equipment.
 
Just think "High rise manifold" from back in the 60's and 70's.
 
I bought a rebuilt 340 that had an airgap on it. Quickly swapped it out for a $50 used Weiand dual plane
that was taking up space. The Weiand ran perfect and the airgap sold immediately at a nice profit. I doubt
if there was any performance difference and the Weiand looked better and was a better intake for a street car.
If you are building day 2 restoration then the LD340 or stock intake are necessary and would be my choice.
I like new things, but not until they get old.
 
Syleng1 said:
So I just used the search feature and they typically sell used on this board for $290-$375 used. For that much money I would wait for an LD-340 intake all day long.
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I'm seeing typical comparable condition LD340 at $100 more than RPM's. I believe there's more opportunity to get a RPM for a greater difference with patience. And the LD340's for sale are generally in worse shape than the RPM (30-40 years newer)

Also having the part number on the LD340 seem to increase the price.

At swap meets around here the RPM's seem half the cost of an LD340
 
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rumblefish360 said:
I’ve seen so many guys go out and get the best of everything, surrender tons of money and get whipped bad, really bad by a guy that got ridiculed for have second rate equipment.
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Used Power & Speed Equipment checking in!

ain't a thing wrong with a factory 4bbl and tq from the yard.

i've seen something like that on top of a 318 with a white box cam flat *** beat the brakes off a 340 with some cam chosen for idle sound and a RPM air gap topped with a QFT 950.
 
The switching around of the runners from lower to upper plane could be due to a couple of reasons that I can think of; one is just packaging. If you look at other brand engines that have the same firing order, they vary in which cyls are upper & which are lower plane. Does it really matter? Somebody at Edel finally woke up [ maybe somebody went to Germany or Japan to see why they there making big HP #s ] that big runners are not as effective as smaller runners, hence the smaller CSA of the Perf intake. The new Perf might have been easier to package with the planes reversed.
The other possibility I can see for switching the planes. #7 fires after #5 cyl, so # 7 can get robbed of incoming charge. Short on air. Moving #7 to the lower plenum which has greater volume, might help with providing more air to #7.
 
Bewy said:
that big runners are not as effective as smaller runners, hence the smaller CSA of the Perf intake.
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This is a CID needing it or not. On a dual plane, I agree. We have seen this before a few times. The newer intake has a better runner and does t need to be large in size. This is why I think it works so well on the street. The air and fuel have an easier time moving into the head and cylinder. Less turning corners closer to a line of sight.
 
Could anyone help me figure out what intake will fit under my hood? I just picked up a 66 dart gt with a 340 bore and stroked. The current intake (Holley strip dominantor an Holley brawler) will not allow for a air cleaner to be on and close the hood! Would anyone be able to point me to a intake that allows the carb to sit at least an inch lower! I don't want to keep spending money to find out that didn't work. I am looking to street drive this darling not drag it but do want the power that I can get when needed! Thanks for any input.
 
I run a LD340 on my small block stroker but I bought that manifold decades back when they were cheap. Wanted to go with RPM intake when I built stroker but Shady Dell said wouldn't see any improvement. Ppl been posting up a lot of newer Edelbrock castings are sloppy these days.
 
A. Edelbrock RPM-AG with a Mancini drop base air cleaner on my ‘67 Cúda.
 
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