David Chan
Active Member
Thanks for the tip !
Dave
Edelbrock LD4B
- Thread starter MOPARJ
- Start date
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Dave
Sounds like you have done a lot to your motor already and the more it is built up, the more you will notice the difference with the LD-4B
David Chan
Active Member
Just reliving my childhood. I factory ordered a 1966 Valiant Signet HiPo 4sp . Loved that car and only drove it for 18 months. Looked for another for decades and finally settled on the 65. I love driving this one as well.
I took a look and decided to follow up here instead for the reason you stated. lol
The lowest rpm I've seen was in Hot Rod Magazine, Aug. 1968 "Building Mopar 340, part 1"
With the stock 340 intake they had some numbers down around 2000 rpm on an engine dyno. I'm sure it some of what (LXguy) are saying about difficulty in consistancy when trying to fully loading an engine at the low rpms. However I did find it interesting that swapping on the LD340 lost a little torque and power under 3500 rpm. From 4000 to the top it was notificibly better than with the factory intake (at wide open throttle). They did no other tuning or testing - this is a 1968 magazine test at Edelbrock's facilities, take it FWIW.
Wow that's cool. That's the way to do it. Wish I was closer. I used the street dominator on my last 340. Still have it. LD340 is currently in use, and an RPM waiting in line which I expect will be better at lower rpm and part throttles due to the runner cross sections and shaping.
So - to your question about the Ed LD4B and the Weiand AP. I don't think so, but lets look. I have a few pictures saved, and thomasclan Mopar A/LA Intakes page is still a handy reference. (right click - view image, for the ones with busted html).
LD4B
Action Plus 7507
Action Plus 8007
Look similar - can see why people get the idea. Same runner pattern, but not quite the same runner shapes. Carb mount obviously different. 8007's plenum is different inside and out for the spreadbore.
I can add a little more about dimensions.
LD340 average mounting pad hieght is 5.12"
LD4B I'm not sure but possibly the same ?
8007 average height of the carb pad is 5.41" (That leaves not much room for a Holley 4150 under 67 Barracuda hood - one reason I went for the LD340)
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The LD4B isn't in the same ballpark as the other 2. The LD4B was designed for the 66 and newer 273 and 318 small port heads. When the 340 came out it was redesigned to be the LD340 for the bigger ports and of course worked well for the 360 also.
The LD4b works almost as well as an LD340. Been a few that have swapped them on 340-360 headed engine and the difference was minimal at best. It's a great performing intake even if it is the small port window which as I've said countless times is the BIGGEST red herring BS in the SB mopar world.
Some of the other intakes that get recommended all the time have the same port window or smaller than an LD4b.
Some of the other intakes that get recommended all the time have the same port window or smaller than an LD4b.
I would imagine Edelbrock used the LD4B casting and tweaked the cores for the exhaust runners to make them 340 size for the LD340. If you have something that works why mess with it any more than you have to. Both manifolds just work!
Actually the LD340 is a complete redisgn.
The runners on the 340 and 4b are reversed. That is why the 4b doesn't have a coil mount. The # 8 runner is the high one and it's the low one on a LD340.
The runners on the 340 and 4b are reversed. That is why the 4b doesn't have a coil mount. The # 8 runner is the high one and it's the low one on a LD340.
I'm never too old to learn. Thanks Cracked!
Edelbrock 'reversed' the ports on the LD340 vs the LD4B... That's why there is no coil mount on the LD4B...
To clarify a little further what I posted.
* Both Action Plus intakes are matched to the 273/318 ports. See thomsclan link for port cast dimensions of various intakes.
* I mocked up installing an 8007 on my '67 Barracuda, that's why I knew how tall it was.
* I mentioned the LD340 only because I don't have a hieght measurement for the LD4B.
* Hot Rod's 1968 340 dyno test used an LD4B. If anyone is really curious, I can post a graph I made of the results - could become a sidetrack. lol.
Rob et al covered the major differences. There also seem to be minor differences under the same name depending on when they were made. Some of the LDs came with Chrysler P part numbers cast in, different ways some accomodated Chysler type choke heaters (or not), and probably a few more.
* Both Action Plus intakes are matched to the 273/318 ports. See thomsclan link for port cast dimensions of various intakes.
* I mocked up installing an 8007 on my '67 Barracuda, that's why I knew how tall it was.
* I mentioned the LD340 only because I don't have a hieght measurement for the LD4B.
* Hot Rod's 1968 340 dyno test used an LD4B. If anyone is really curious, I can post a graph I made of the results - could become a sidetrack. lol.
Rob et al covered the major differences. There also seem to be minor differences under the same name depending on when they were made. Some of the LDs came with Chrysler P part numbers cast in, different ways some accomodated Chysler type choke heaters (or not), and probably a few more.
I have both a LD340 and LD4B bolted on engines, I could measure the height of the carb flanges, by laying a straight edge across factory valve covers.
But not until the east coast thaws out a little bit.
But not until the east coast thaws out a little bit.
LXguy
Well-Known Member
I just bought an LD4B off ebay for the slightly unreasonable price of $250 shipped. Going to dyno test this with the Action Plus back to back on my 318 Satellite when the weather gets a little warmer.
That cam is close to the Crane Blazer that I ran in My teener, short on lift by comparison, but duration #'s are pretty close....
That cam is close to the Crane Blazer that I ran in My teener, short on lift by comparison, but duration #'s are pretty close....
Yes all very interesting. Considering that Chrysler supplied single plane intakes on 273s, I'm not convince the short runners and combined plenum are always a loss at street rpms and low throttle. Keep us posted. This will be awsome.
Mattax,
Holley street dom intakes, especially for the BB are stout intakes.
Holley street dom intakes, especially for the BB are stout intakes.
Sounds interesting.
LXguy
Well-Known Member
I chose the Summit 6901 for the wide LSA to keep what meager compression the 318 had and for the nitrous. Its also got a very fast (I think 34* ABDC) exhaust valve closing event to help preserve dynamic compression. Somehow, it sounds pretty badass also!
Rob - I think we agree. My point was that people too often dismiss it for lower and mid range performance just because its a single plane. They shouldn't. I used the factory single planes as examples where the generalization about single planes is just that, a generalization. Clearly the factory didn't think it was an absolute.
Chrysler 2465726 273 4 bbl intake, 1965 (from the sthoms Intakes webpage)
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It certainly has a nice lope. Do you need a higher stall converter?
LXguy
Well-Known Member
toolmanmike: I have a restalled stock converter. I am sure a looser one would be better, but I drive the car a lot when the weather is nice and its fine.
Mattax: Yes, that 273 intake looks like a 4 bbl version of the factory intake that came on this 318. Obviously, this 318 single plane was not intended as a high rpm screamer as it would only rev to 3500 rpm on the dyno-LOL. I've often wondered if they did them that way for hood clearance. My LD4B and Action Plus intakes are on the way. I'll be sure to baseline the Street Dominator that is currently on the motor before installing the other intakes so we'll have a three-way comparison. I'm very interested to compare torque production between the three of them.
It's interesting that nobody sells a small-runner low-profile single plane intake and claims its a torque improvement anymore.
Mattax: Yes, that 273 intake looks like a 4 bbl version of the factory intake that came on this 318. Obviously, this 318 single plane was not intended as a high rpm screamer as it would only rev to 3500 rpm on the dyno-LOL. I've often wondered if they did them that way for hood clearance. My LD4B and Action Plus intakes are on the way. I'll be sure to baseline the Street Dominator that is currently on the motor before installing the other intakes so we'll have a three-way comparison. I'm very interested to compare torque production between the three of them.
It's interesting that nobody sells a small-runner low-profile single plane intake and claims its a torque improvement anymore.
My favorite thing to do is what you are about to do. I'm tuned in
I did a similar test last year on my 318 Duster, pulled a factory cast '73 340 intake off and put a Holley Street Dominator on. Compared E.T. slips.... wasn't the same day, so possibly a small variation, but still, it was interesting.
I also made the change from the performer to the ld4b and noticed a performance improvement
Here is some compares between the intakes
Performer - carb height 4.63" with Port Exit .95" x 1.95"
LD4B - carb height 4.9" with Port Exit 1.05" x 1.95"
LD340 carb height 5.25" with Port Exit 1.07" and 2.16"
RPM carb height 5.35" with Port Exit 1.01" x 2.17"
Here is some compares between the intakes
Performer - carb height 4.63" with Port Exit .95" x 1.95"
LD4B - carb height 4.9" with Port Exit 1.05" x 1.95"
LD340 carb height 5.25" with Port Exit 1.07" and 2.16"
RPM carb height 5.35" with Port Exit 1.01" x 2.17"
Here's a plot of the first three dyno pulls from Hot Rod, August 1969. John Dianna "Mopar Manipulatin' Part One"
1. Baseline, Stock 340 (including air cleaner) 39 degree advance.
2. Installed Hooker fenderwell type headers
3. Swapped on LD-4B intake. Reinstalled factory Carter AVS, no change in jetting.
After that they did some engine work including preloading the lifters .020" to eliminate the valve float before 6000 rpm. And after that about 15 more modifications and pulls!
1. Baseline, Stock 340 (including air cleaner) 39 degree advance.
2. Installed Hooker fenderwell type headers
3. Swapped on LD-4B intake. Reinstalled factory Carter AVS, no change in jetting.
After that they did some engine work including preloading the lifters .020" to eliminate the valve float before 6000 rpm. And after that about 15 more modifications and pulls!
In part 1 of the article mentioned above, with a cam change on a stock motor they got an STR-12 and 2 Holley 600s to put out 450 hp at 6750 rpms, and in part 2 (Sept '69 Hot Rod) they got a modified 340with the STR-12 and 2 600s to put out 487 hp at 6750. Not bad for 1969 technology with a motor that had only been around a year.
That same article compared the LD4B and an LD340 on the 340, and the LD340 was worth an additional 15 to 30 hp between 4500 and 5000 rpms on the same motor. In the spirit of this thread, the LD340 would not work well on the smaller port 318/273 heads, unless you port matched the heads to the manifold.
That same article compared the LD4B and an LD340 on the 340, and the LD340 was worth an additional 15 to 30 hp between 4500 and 5000 rpms on the same motor. In the spirit of this thread, the LD340 would not work well on the smaller port 318/273 heads, unless you port matched the heads to the manifold.
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