340 Intake manifold help

-
dancinwulf

dancinwulf

Well-Known Member
Joined
Apr 8, 2015
Messages
101
Reaction score
15
Location
Ketchum Idaho
I have a 73 340 that is stock but I have three different manifolds to choose from would appreciate any advice as to which might be best not looking for a race car just want to get the most out of it. I have the stock 340 manifold and a Edelbrock RPM performer and a Mopar that I think is an M1
 

Attachments

  • photo.jpg
    43.8 KB · Views: 441
  • photo 2.JPG
    53.3 KB · Views: 414
RPM gets my vote. Don't count the stock intake out as it is a very good peice.
 
X5 ! lol

They were all very similar, but I'm curious what the casting number is on the cast iron intake. You can PM me if you'd like.
 
Looks to be a 360 intake judging by the offset water outlet. No real difference performance wise though.
 
Use the stock one if your going to keep the t quad with a working choke, otherwise use the eddy with a 750 vacuum secondary holley with the correct throttle kickdown adapter. The HP difference will be very small on a stock engine.
 
I am planning on using the T Quad the stock manifold is off a 73 340 I had it media blasted and was going to have it cleaned out as well but had heard from a friend that the Eddy was a good choice but not sure if it will work well with the T Quad will it?
 
You'll need an adapter to use the TQ on the RPM. That usually reduces air flow a bit and it wouldn't hurt to check the hood clearance.

As screws pointed out, the OEM intake is originally from a 360, late '70's or somewhere in the '80's. That's when they used the smaller, offset thermostat housing because of a new design A/C compressor. Someone must have installed it on your 340 in the past. I don't really need another for the NHRA/IHRA Stock class car that I'm working on but was wondering if it's one of 3 legal castings allowed for my combo or a later version.
 
The 1973 340 Cast Iron Intake Manifold > {#3671918}

It is kind of 'clunky', and has a few more EGR ports than the 1971 Manifold,
and the 1972 Manifold.

Though it flows well for a 'stock' unit, it has a bigger Heat-Crossover passage
than the earlier 340 Intake Manifolds.

It is 'bulky' as well {nearly 50 lbs}.

But that being said, that 'Baby' loves the Thermoquad.
 
Start with plan A.

If that doesn't work out, then go to plan B.

If all else fails, you can go to plan C....
 
dancinwulf said:
I have a 73 340 that is stock but I have three different manifolds to choose from would appreciate any advice as to which might be best not looking for a race car just want to get the most out of it. I have the stock 340 manifold and a Edelbrock RPM performer and a Mopar that I think is an M1
Click to expand...

A OEM intake range is approx. idle to 6000
The RPM has a range of 1500 - 6500
The M-1 has a range best suited of 3000 - 7000+

A OEM intake work well with mild hop ups for fairly good street machines. No problem making 400 HP & a little more.

A RPM is a excellent intake capable enough to get your car into the 11's while retaining a lot of street clothing. Full interior, wipers, heater, etc... 500+ HP is not a problem.

The M1 single plane works really well in a heavy hitting machine and race cars. Copied and updated from the early years Holley Strip Dominator, the killer intake back in the hay days, this manifold gives up lower end torque for higher RPM HP. It is streetable but better suited the strip. 10 second runs and quicker are possible. Be prepared to lighten your car big time and build a monster motor with race grade everything. You'll pick'en up and lay'em down.

A good general gear ratio range to use with the above intake but not limited in anyway shape or form could be seen like;

OEM, stock Hwy. gears up to 4.10
RPM, 3.21/3.23 up to 4.56
M1 - what ever the best needs, but not less than 3.91

This guide line is just that, a guide line suggested to help keep a balanced power plant and car. This doesn't exclude intake modifications to make the intake perform above and beyond there basic design and intended use.
 
rumblefish360 said:
A OEM intake range is approx. idle to 6000
The RPM has a range of 1500 - 6500
The M-1 has a range best suited of 3000 - 7000+

A OEM intake work well with mild hop ups for fairly good street machines. No problem making 400 HP & a little more.

A RPM is a excellent intake capable enough to get your car into the 11's while retaining a lot of street clothing. Full interior, wipers, heater, etc... 500+ HP is not a problem.

The M1 single plane works really well in a heavy hitting machine and race cars. Copied and updated from the early years Holley Strip Dominator, the killer intake back in the hay days, this manifold gives up lower end torque for higher RPM HP. It is streetable but better suited the strip. 10 second runs and quicker are possible. Be prepared to lighten your car big time and build a monster motor with race grade everything. You'll pick'en up and lay'em down.

A good general gear ratio range to use with the above intake but not limited in anyway shape or form could be seen like;

OEM, stock Hwy. gears up to 4.10
RPM, 3.21/3.23 up to 4.56
M1 - what ever the best needs, but not less than 3.91

This guide line is just that, a guide line suggested to help keep a balanced power plant and car. This doesn't exclude intake modifications to make the intake perform above and beyond there basic design and intended use.
Click to expand...

Well stated sir, well stated.
 
Thank you, thank you. I was going to input cam selections but based on the general RPM ranges of the intakes. Cams can be selected for use by there intake ranges given by the manufacturers of the cams with very good results even for the novice.

By matching the cams RPM range to the general listing ranges of the intakes above, a good match can be made. For the novice out there, do not worry so much. More is lost at the starting line and the tune up before hand. Just get out there and enjoy!

Cams, carbs & intakes can be changed out like socks, underwear & pants.
 
So I am thinking I might go with the RPM but with that said what about carburation I am told the T Quad doesn't work with that manifold very well so what else would be good I have a Eddy 650 but wasn't sure if that was big enough. My other option would be just to use the OEM and the T Quad and call it good I truly appreciate all the good advice thanks to all of you who have commented
 
That carb doesn't work with that intake period unless you use an adapter. That would not be my choice combo to do. Better off with a Weiand Action Plus or a previously modded LD340. The mod you can do yourself if you wished to. A die grinder and gasket to trace is all it takes.

The stock intake and carb are capable.

What is the cam specs and gear ratio?
What is the intended target and useage of the ad?
 
I think that is what I am going to do stick with the OEM and the TQ it seems to be the simplest and probably the least trouble some. Thanks again for all the advice.
 
And just because its on there, doesnt mean it has to stay on there.lol. Its not like you welded it together.
Should the day come that you just gotta know, a swap is just a few bucks and a couple of hours away.
But get to know that oem unit first.Let it be there for a few weeks/few hours.Get your ignition and fueling dialed in. Feel the torque, the midrange, where does the power really start, and when is it done. Enjoy the choke starts. get that figured out. ETC.
 
The rpm performer and a properly tuned holley 750 vacuum secondaries on your 340 will kick *** all day long on a "plastic" body carb and stock manifold...:D:D
 
And that's why I actually LOL, and had to reply with it.
You should be paid by Holley!
 
You must log in or register to reply here.
-

Back
Top