Ld340 or rpm airgap

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1965 Barracuda Mtl

1965 Barracuda Mtl

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Hello

I have a 1965 barracuda with a 340 0.030. Holley 600cfm and a lunati voodoo cam 10200703. Car has a little over 400hp and 415tq. I currently have a Ld340 intake manifold but am considering changing for a Rpm air gap intake manifold. What are the benefits in switching, will I gain any power and is it worth it?
Thank you
 
Not too much gain. The LD is a good intake. So is the Air Gap for that matter. Maybe someone has some hard numbers but I am guessing not much more than 10 maybe 15 horse at the most.
 
On the LD340, I'd just tune the 600 DP. A slightly larger carb falls in your lap, then its worth experimenting.
Running an LD340 on the current 340 and in the lower rpm ranges I think it looses velocity in the runners.
I've had an non-airgap RPM sitting on the shelf for a few years now but haven't had an opportunity to swap them.
IMO decent headers and exhaust will help keep things flowing into the cylinders.

A larger carb may pay off at the track if you're looking for more top end in the 1/4 mile.

Should add my current 340 has a Hughes cam in the same range as that Lunati. something like 223/230 505/515 or so

Not sure I'd use air gap version in Canada. All depends on how you use the car and what sort of fuel your running.
 
Last edited:
1965 Barracuda Mtl said:
Hello

I have a 1965 barracuda with a 340 0.030. Holley 600cfm and a lunati voodoo cam 10200703. Car has a little over 400hp and 415tq. I currently have a Ld340 intake manifold but am considering changing for a Rpm air gap intake manifold. What are the benefits in switching, will I gain any power and is it worth it?
Thank you
Click to expand...
The benefits of switching to an RPM don't outweigh the benefit of switching to a 750 double Pumper. From 4000-4500rpm is where the 750 BEGINS to leave the 600 behind.. it just flat out will make more torque up there and of course hp/rpm jumps
 
Mattax said:
On the LD340, I'd just tune the 600 DP. A slightly larger carb falls in your lap, then its worth experimenting.
Running an LD340 on the current 340 and in the lower rpm ranges I think it looses velocity in the runners.
I've had an RPM sitting on the shelf for a few years now but haven't had an opportunity to swap them.
IMO decent headers and exhaust will help keep things flowing into the cylinders.

A larger carb may pay off at the track if you're looking for more top end in the 1/4 mile.

Should add my current 340 has a Hughes cam in the same range as that Lunati. something like 223/230 505/515 or so

Not sure I'd use air gap version in Canada. All depends on how you use the car and what sort of fuel your running.
Click to expand...
I have hooker headers and just redid the exhaust last year to a full stainless 2.5" exhaust with an h pipe. I always fill up 94 octane in it. I don't track the car but when I push it I like it to move
 
I guess there's not much to gain anymore unless you go deeper... like cylinder heads (what's your compression now?) ... or just stroke it.
 
Another consideration is when and how often you plan to drive it. Cold weather drivability should be better with the LD340 because the Air-Gap obviously doesn't have the heat crossover.
 
I thought that one of the benefits of the air gap was that it helped cool the fuel by allowing air to pass under the carb plenum. Living in Canada...........I don't see how the air gap would help since the air up there is already pretty damn cool and summers are mild???
 
get a better carb , the LD340 is a pretty good intake , not much gain with air-gap except cold weather start up problems . though I had one , with electric choke it worked well but it took a while to warm up and be driveable
 
You could t take two minutes to copy and past your specs? Really?!?!

Cam Style:Hydraulic flat tappet

Basic Operating RPM Range:1,800-6,200

Intake Duration at 050 inch Lift:226

Exhaust Duration at 050 inch Lift:234

Duration at 050 inch Lift:226 int./234 exh.

Advertised Intake Duration:268

Advertised Exhaust Duration:276

Advertised Duration:268 int./276 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.494 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.513 in.

Valve Lift with Factory Rocker Arm Ratio:0.494 int./0.513 exh.

Lobe Separation (degrees):110
 
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