What can you tell me about the Mopar dual plane intake manifold?

[DartThis74]

Very long story short, I have a mild build 360 in my Dart Sport. I was told it is an 80s model engine with no knowledge of type of vehicle it was pulled from. I had since gone through it and upgrade to a lunati voodoo (LUN-60401LK) cam back in early 2000s. Pistons bored 30 over and I had someone offer me this Mopar dual plane intake (I think part P4532058) which I installed on it. Pretty much the end of the work done on this stock engine. More to the long story, a "performance shop" offered to install a Holley HP Ultra carb sitting on the shelve to replace the old crapped out Holley I had on it, so I said why not. The HP Ultra was definitely not the right carb for this engine and I've had problems ever since as this was really meant for truly racing and wide open throttle, which this car is not at all about. I now have a quadrajet installed on the engine with a special modified adapter plate to go from spread bore to square bore to fit this Mopar intake, but of course the airflow is restricted to some extent because of this adapter. I have on hand an actual stock iron spread bore intake off an LA small block that I could swap out in place of this Mopar intake I have, but would there really be any added benefit to doing this ? Why is this Mopar dual plane intake sought after by people ? Is it really a performance enhancer to the air system over any other modern design intake ? What even type of engine or vehicles had these intakes been installed on from the factory ? Should I be talked out of swapping out the intakes I guess is my question? haha thanks for any information about this.

 

[dogbreath]

mopar performance aluminum version of what you already have.

 

[TT5.9mag]

Leave the intake alone. What you have is fine for what you are doing and the cast iron 4 barrel intake will be no better. Throw the adapter in the trash along with the quadrajet garbage. Put the Holley back on it and find someone that knows how to tune it properly. The ultra HP is not a “race only” carburetor and can be tuned to drive just fine even on mild stuff. Tuning is your problem, PERIOD.

 

[George Jets]

That's a good Square Bore aluminum dual plane intake manifold you have there

Being you are saying it's a stock build, put an Edelbrock 1406 (with electric choke) square bore 4 bbl on it and your troubles will be over.

Gone, Gone, Gone...

No special tuning required, bolt on and go.

.

 

[ch1ll]

While all cast iron 340-360 stock intakes are good manifolds with the the 1971 being the best of the bunch, the mopar aluminum manifold is better. I agree that tuning your hp carb is the answer to your problems.

If your looking for more, you can't go wrong with having your intake ported and your heads as well by a reputable porter. It's performance upgrade that doesn't wear out. Charles Servedio in Florida
Is an awesome porter and he has small block mopar experience.

 

[Darter6]

all cast iron 340-360 stock intakes are good manifolds

The only difference is the cast ones weigh about 50 lbs.
That Mopar aluminum is about the best dual plane out there.

 

[toolmanmike]

@DartThis74 That intake is close to the Edelbrock LD340 design. The 58 is supposed to be a single plane and the 59 is a dual plane from what I have read. It should be a perfect manifold for your combination.

 

[TT5.9mag]

That Mopar aluminum is about the best dual plane out there.

Nope. It’s ok and is better than a few and worse than a few. The RPM and the RPM air gap beat it handily. By 15 numbers on my mild 360. That being said it’s perfect for the OP.

 

[toolmanmike]

Nope. It’s ok and is better than a few and worse than a few. The RPM and the RPM air gap beat it handily. By 15 numbers on my mild 360. That being said it’s perfect for the OP.

That Air Gap is a mini tunnel ram.

 

[340six]

That Air Gap is a mini tunnel ram.

I still want a LD-340 and or the Mopar LA Duel Plane with normal center thermostat like OP has.
Like everything else finances dictate other wise.

 

[DartThis74]

Thanks for those input guys, considering the Mopar intake is hard to come by I never considered getting rid of it, but was more curious is there really a benefit of having it over the cast iron intake. So, what is special about this intake though other than being aluminum and perhaps better flow design ? Was this a special intake only purchased through the Mopar Performance parts program, or were some engines equipped with this manifold from the factory ? If so what vehicles were these ? I am having a hard time really understanding this intake and it being special to people.

Side note on the carburetor, I've always had issues with the Holley Ultra HP. I've take it to several shops around the area and they get it tuned to their liking, but it always without fail started to stumbled and typically just would fall flat on its face when stepping into the accelerator. Life got in the way and the engine sat around for few years with old gas in the carb so it got seized up. A neighbor of mine is a gearhead primarily specializing in Quadrajets and had many of them laying around and wanted to help me out and get this car back on the road. So, he gave one to me for free all tuned up and we slapped it on with the special adapter. It fired right up and ran exceptionally well, given I was getting about 10mpg with the Holley, I'm looking forward to perhaps getting better milage from the Quadrajet. Though Holley's are more plentiful and easier to work on I suppose, I'm not opposed to running this Quadrajet if it runs really well and gets my car moving like I want it to.

 

[toolmanmike]

Thanks for those input guys, considering the Mopar intake is hard to come by I never considered getting rid of it, but was more curious is there really a benefit of having it over the cast iron intake. So, what is special about this intake though other than being aluminum and perhaps better flow design ? Was this a special intake only purchased through the Mopar Performance parts program, or were some engines equipped with this manifold from the factory ? If so what vehicles were these ? I am having a hard time really understanding this intake and it being special to people.

So, what is special about this intake though other than being aluminum and perhaps better flow design ? Was this a special intake only purchased through the Mopar Performance parts program.

You answered your own question. None came with it installed. The only aluminum intakes from the factory were the Edelbrock 6 pack manifolds on 340's and 440's.

 

[PROSTOCKTOM]

That Mopar aluminum intake is just a copy of a really good 1969 intake. Other than a weight reduction they are the same intake.

Tom

 

[Bodyperson]

That Mopar aluminum intake is just a copy of a really good 1969 intake. Other than a weight reduction they are the same intake.

Tom

Not exactly the same. The cast iron has four holes.

 

[DartThis74]

So, what is special about this intake though other than being aluminum and perhaps better flow design ? Was this a special intake only purchased through the Mopar Performance parts program.

You answered your own question. None came with it installed. The only aluminum intakes from the factory were the Edelbrock 6 pack manifolds on 340's and 440's.

Thanks and that's what I wasn't sure of how people got their hands on these back in the day. Did you have to go into the dealership and special order this from the parts counter or something?

 

[340six]

Thanks and that's what I wasn't sure of how people got their hands on these back in the day. Did you have to go into the dealership and special order this from the parts counter or something?

Or mail order. Was common.
Same way you bought camshaft, heads, sixpack stuff, ect

 

[MOPARMAGA]

That Air Gap is a mini tunnel ram.

I just spoke to tunnel ram, he said NO !

 

[66fs]

... It fired right up and ran exceptionally well, given I was getting about 10mpg with the Holley, I'm looking forward to perhaps getting better milage from the Quadrajet. Though Holley's are more plentiful and easier to work on I suppose, I'm not opposed to running this Quadrajet if it runs really well and gets my car moving like I want it to.

So why mess with anything else. A good Q-Jet is a great street carb, power and mpg. Either intake is good, take your pick. Cast iron is good forever even if it does weigh 25 more pounds than aluminum.

 

[TT5.9mag]

I just spoke to tunnel ram, he said NO !

I laughed,


HARD

 

[Mattax]

LUN-60401LK cam + Holley HP Ultra carb or old crapped out Holley, or quadrajet installed on the engine with a special modified adapter plate

Leave the intake alone. What you have is fine for what you are doing and the cast iron 4 barrel intake will be no better. Throw the adapter in the trash along with the quadrajet garbage. Put the Holley back on it and find someone that knows how to tune it properly. The ultra HP is not a “race only” carburetor and can be tuned to drive just fine even on mild stuff. Tuning is your problem, PERIOD.

Agree 100%. This is the next stage of your journey.
The only choice now is which carb. Any of them can be made to work decently. I don't like adapters for a variety of reasons.
That leaves the two Holleys. I don't know what the "crapped out" one is, but frequently the older ones require less work to get good performance, especially street performance. Start a new thread, post up some photos with the list numbers.

Performance tuning isn't like a tune up. It's process.
A few things will come first.
1. Check the float levels (dry) or fuel level (wet).
2. Measure and set the transfer slot exposure (primary side). Write down how turns needed (see linked post)
3. Estimate the initial timing.

Searching the web quickly, it looks like that camshaft is 213/220 durations @ .050" lift, 112 LSA and
0.454 int. / 0.475 exh. lift

I'd probably try 16 deg initial as a baseline, but if that's too difficult to start tuning with, then give it another degree or two.
Keep in mind initial timing is the timing with no advance. That might be 600 or 750 rpm. You'll have to measure with a tach and find out. I mention it because checking timing at 1000 or 1200 rpm will not be initial. If that's what you have to do, then you'll have to set it higher than 16, something like 20 BTC. and then see what it is at lower rpms once you can get the engine to idle slower.

Link

Post in thread 'Looking for more pep off the line'

Sep 4, 2023

With a Holley 4150/60.
First. Always check fuel level in both bowls before getting into the tune.
Most have sight plugs on the bowl. Traditional sight plugs are located so the fuel level should be just at the bottom of the plug (primary) and a little lower on the secondary bowl. New big clear window plugs aer usually set near the middle.

With carb off the engine check the primary transfer slot exposure under the throttle plates at idle are in the range of .020 - .040"
If it gets out of range, then there will be a delay or bog while driving or accelerating as the...

• Mattax