LD340 v Airgap

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raymond

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Hi guys , anyone swapped from an LD 340 to an airgap on a 360 and if so did you see any improvements? Any input would be much appreciated, thanks
 
With a Edelbrock Air Gap about 15 HP+ at
6000 on a well prepared 550 HP 360 that was
in our 10 Sec Valiant.
 
From what I remember, there was a small gain not worth the price. A few fellas called up Edelbrock and asked about this very thing. According to what they were told, it wasn’t really worth swapping. But there is a gain. One of the things to consider if you’re thinking about this is the intake remains a little cooler.
Eventually, all intakes get soaked with heat. The RPM-AG is a little less.

I have run both. My LD-340 was modified via the MP book’s instructions. A milled divider and opened up to use a TQ. It was a very power intake. When the TQ was at WOT, it was a screamer. Between the two, I’d need a dyno to tell you which one was better.
 
Did you double post this?

I just left a reply….

FWIW, my engines were not as powerful or well prepped as GTX John engines are. They were basic rebuilds with higher compression pistons and a relatively small cams by compare to what he races with.
 
Do yourself a favor and make just one thread or you’ll be jumping back and forth between threads. It tends to a bit convoluted when there’s multiple threads on the same question in different sections.

A copy and paste from the other thread;

From what I remember, there was a small gain not worth the price. A few fellas called up Edelbrock and asked about this very thing. According to what they were told, it wasn’t really worth swapping. But there is a gain. One of the things to consider if you’re thinking about this is the intake remains a little cooler.
Eventually, all intakes get soaked with heat. The RPM-AG is a little less.

I have run both. My LD-340 was modified via the MP book’s instructions. A milled divider and opened up to use a TQ. It was a very power intake. When the TQ was at WOT, it was a screamer. Between the two, I’d need a dyno to tell you which one was better.
 
Do yourself a favor and make just one thread or you’ll be jumping back and forth between threads. It tends to a bit convoluted when there’s multiple threads on the same question in different sections.

A copy and paste from the other thread;

From what I remember, there was a small gain not worth the price. A few fellas called up Edelbrock and asked about this very thing. According to what they were told, it wasn’t really worth swapping. But there is a gain. One of the things to consider if you’re thinking about this is the intake remains a little cooler.
Eventually, all intakes get soaked with heat. The RPM-AG is a little less.

I have run both. My LD-340 was modified via the MP book’s instructions. A milled divider and opened up to use a TQ. It was a very power intake. When the TQ was at WOT, it was a screamer. Between the two, I’d need a dyno to tell you which one was better.
Thanks for the reply, my LD has the TQ mods plus when I got hold of it the WHOLE divider had been removed along with just about everything else in the plenum, it's not a pretty sight, I'm thinking the mods haven't helped it. Its in a 68 Dart has around 10.8 or 9 comp Eddies at mid 280's hyd / roller 222@.050" 1.6 rockers 999trans and 3.5 gear, It's gone 11.50 in really good air, it could probably use some more cam but I'm old and grumpy and more cam will drive me crazy. I'm thinking if there might be a bit in the AIRGAP for me I might grab one.
 
I liked the LD 340 better. I found this aluminum intake pictured and like it due to being able to use the factory carb and choke and has the coil mount. lso the same factory height

001.jpg
 
Hood clearance will be better with the ld340
 
Thanks for the reply, my LD has the TQ mods plus when I got hold of it the WHOLE divider had been removed along with just about everything else in the plenum, it's not a pretty sight, I'm thinking the mods haven't helped it. Its in a 68 Dart has around 10.8 or 9 comp Eddies at mid 280's hyd / roller 222@.050" 1.6 rockers 999trans and 3.5 gear, It's gone 11.50 in really good air, it could probably use some more cam but I'm old and grumpy and more cam will drive me crazy. I'm thinking if there might be a bit in the AIRGAP for me I might grab one.
The mods helped it BUT you’re NOT taking advantage of it at all, not one bit. The RPM will be what you need with that tiny camshaft you have. No doubt!!!

As the MP book states, for cams with .600 lift or better. Now, take a trip through the history books (AKA The old catalogs) and see what MP has for cams in the .600 lift area. See what other manufacturers have for advertised and figures at .050 for duration.

What you have is a mild street performance cam that can use ether the Factory 4bbl., Edelbrock Performer, RPM/RPM-AG, Weiands Action Plus or the Stealth.

The cam I had a hen I used it, was more than 20*’s @.050 larger than yours and to be honest, it was still small for that intake with the mods. I should have used a cam with 20 more degrees of duration and a bit more lift.

Currently I have a 224@050 in a 360 working with a RPM-AG.
It’s a good match.
I liked the LD 340 better. I found this aluminum intake pictured and like it due to being able to use the factory carb and choke and has the coil mount. lso the same factory height

View attachment 1716035259
Ahhhhh, the standard MP dual plane. A copy of the early 340 intake. Surprisingly good!
 
The air gap is better by a small percentage. The more hp you have, the better a gain you will see.

As for me, I would keep the LD and spend the money on porting it and the heads.
 
The problem is the plenum has probably been butchered past the point of fixing it, it's a real mess. The heads are already flowing in the mid 280,s. My thoughts were to try an Air Gap to get away from the butchered LD and take advantage of the slight gains the AG is said to have.
 
It’s fixable with a tig welder
I'm down under, the LD has other problems as well it looks to have been pretty badly corroded in the water ports and was welded then machined, by a blind person by the look of it, it is now 'low' at 5/7 ports , trying to fix it is $$$prohibitive, for me anyhow, I'm over it. Thanks for you thoughts on it.
 
I'm down under, the LD has other problems as well it looks to have been pretty badly corroded in the water ports and was welded then machined, by a blind person by the look of it, it is now 'low' at 5/7 ports , trying to fix it is $$$prohibitive, for me anyhow, I'm over it. Thanks for you thoughts on it.
 
Any pictures of it so we can see what you are talking about? If it needs a ton of work might be better to get an Eddy air gap. But they are both great intakes, I think they are rated as the best 2 manifolds you can buy for all around performance. I have an air gap on my 69 340, stick X heads, MP purple .509 can and a 750 VS Holley and it works great. I also have a nice LD340 that’s for the old Direct Connection mid for a thermoquad, haven’t tried it yet. If you go air gap….don’t cheap out and get a knock off China version, get the one from Edelbrock. Another thing to consider, if “down under” shipping might be a lot for you…could use that $ to fix your old manifold.
 
Thanks for the reply, my LD has the TQ mods plus when I got hold of it the WHOLE divider had been removed along with just about everything else in the plenum, it's not a pretty sight, I'm thinking the mods haven't helped it. Its in a 68 Dart has around 10.8 or 9 comp Eddies at mid 280's hyd / roller 222@.050" 1.6 rockers 999trans and 3.5 gear, It's gone 11.50 in really good air, it could probably use some more cam but I'm old and grumpy and more cam will drive me crazy. I'm thinking if there might be a bit in the AIRGAP for me I might grab one.
I had a very similar street combo, except with a manual trans.The cam was a Hughes 223/230/110, and the intake was an AG. I loved that combo; gobs of low-rpm torque, a solid midrange and adequate top-end.
When that cam died, I installed a Hughes 230/237/110 and bumped the DCR back up to, maintain 180psi .
The engine got a whole new personality.
I went to the track just one time, and she pulled 93mph in the Eighth, at 3650pounds/900ft elev.

I liked the first cam better. it had a significantly stronger low-rpm torque, that a manual-trans car really needs. The top-end was not as strong, but in a streeter with 3.55s that was not a big deal. IMO it was Not a good swap. I have been waiting since 2004 for that 230 cam to lose lobes, so I can go back, lol.
 
Any pictures of it so we can see what you are talking about? If it needs a ton of work might be better to get an Eddy air gap. But they are both great intakes, I think they are rated as the best 2 manifolds you can buy for all around performance. I have an air gap on my 69 340, stick X heads, MP purple .509 can and a 750 VS Holley and it works great. I also have a nice LD340 that’s for the old Direct Connection mid for a thermoquad, haven’t tried it yet. If you go air gap….don’t cheap out and get a knock off China version, get the one from Edelbrock. Another thing to consider, if “down under” shipping might be a lot for you…could use that $ to fix your old manifold.
Thanks for your thoughts, yeah it seems the airgap is out of stock everywhere I look but I wasn't planning on going with the china one. The best price I can see her in OZ was from Amazon believe it or not, but they have no stock either, [not a cheap option to ship from US] I've ordered from them and they will bill me and send when they become available. Don't have any pix of my LD , Cheers.
 
They say the runners are straighter with rpm, but I think power wise the difference is mainly in plenum height.
So a 7/16 spacer should even the playing field.
The ld340 has wider runners.
 
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