Edelbrock LD4B

318willrun said
I started a thread on "Action Plus vs...." to see if there was an intake for my particular combo that would offer a gain. The thread left the intake subject pretty fast, but I like stuff like this. The Action plus has performed very well.

I took a look and decided to follow up here instead for the reason you stated. lol

LXguy said
toolmanmike said

It would be interesting to dyno a 273 with the HP manifold vs the LD4B. (and start the readings out at 1000 rpm instead of 3000 like most dyno operators do)

Click to expand...

As you're going for consistency this is nearly impossibly to do. As soon as you WOT it, it is going where the converter flashes anyway. Doing it twice for a back to back comparison consistently would be unlikely. How long are you at WOT under 3500 RPM anyway?

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.

I've got a Mustang dyno and I can do part throttle dyno pulls as well as WOT, which would be useful for really comparing the intakes. I've even got a 318 powered plymouth, but it currently has a Holley Street Dominator on it.

I am very curious to know if the LD4B is really better than the Performer, and I want to know if the LD4B is the same thing as the Weiand Action Plus, but I'm not spending $750 on intakes to find out. haha.

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)