M1 Intake Manifold SBM

[340inabbody]

Hey guys! I am having a real challenging time getting my 340 with an M1 single plane intake and a Holley 4150 to fit under my hood on my 1970 Roadrunner with an Air grabber hood. I have a few questions for you guys regarding the M1.

1. Is the M1 that much taller than an Eddy Performer or Air Gap?

2. On the M1 it might be necessary to add a vacuum line but where to drill? Is there a good place to add a port or no?

3. Posted on the Bbody site. Thinking of disconnecting the PCV to the manifold due to current port limitations. With a check valve on does the lack of vacuum prevent proper ventilation ? Is there an easy was to passively port the PCV?

Thanks yall!

 

[rumblefish360]

Hey guys! I am having a real challenging time getting my 340 with an M1 single plane intake and a Holley 4150 to fit under my hood on my 1970 Roadrunner with an Air grabber hood. I have a few questions for you guys regarding the M1.

Use a drop base filter air cleaner set up from Mancini

1. Is the M1 that much taller than an Eddy Performer or Air Gap?

I’m not sure on this. Edelbrock should have manifold height on there see site but for sure in the paper catalog.

2. On the M1 it might be necessary to add a vacuum line but where to drill? Is there a good place to add a port or no?

For what? On the intake runner closest to what it is you need it for.

3. Posted on the Bbody site. Thinking of disconnecting the PCV to the manifold

Stop right there, the PVC connects to the carb at the front on the carb. Not the intake manifold.

With a check valve on does the lack of vacuum prevent proper ventilation ?

The PVC valve should have a check ball or something or the sort in it.

Is there an easy was to passively port the PCV?

Port the PVC valve? What in earth would you port a PVC?
There is no good reason, zero, none, Nada, zip!!!

Thanks yall!

 

[rumblefish360]

Also, FWIW, the M1 single is a racing intake and not designed for the street. That’s why it lacks certain provisions.

 

[340inabbody]

Use a drop base filter air cleaner set up from Mancini
Using a drop base currently. I’ll provide a picture.

I’m not sure on this. Edelbrock should have manifold height on there see site but for sure in the paper catalog.
Thanks I’ll check.

For what? On the intake runner closest to what it is you need it for.
For PCV

Stop right there, the PVC connects to the carb at the front on the carb. Not the intake manifold. Thats right and thats where it’s at via a spacer that I want to take out. But don’t know if the ventilation would be adequate with just a check valve on the driver valve cover and a breather on the passenger side? Thats my main question actually.

The PVC valve should have a check ball or something or the sort in it.
Yes it does and goes to the front under the carb into a spacer see pic.

Port the PVC valve? What in earth would you port a PVC?
There is no good reason, zero, none, Nada,

 

[12many]

The spacer is likely the issue. Not much difference in height between the Air Gap, M1 single, or a Weiand Action + Ive run all three under a very limited space doghouse with custom two piece airbox. 1/4” difference at most.

 

[340inabbody]

Also, FWIW, the M1 single is a racing intake and not designed for the street. That’s why it lacks certain provisions.

Yeah thats how it came. I should replace it huh? Its an automatic as well. I really could use some advice on how to set up a 340 for this application. I am trying to learn as I go.

 

[340inabbody]

The spacer is likely the issue.

Yup I need to jettison it. Just don’t know what I need to do with the PCV set up..??

 

[Mtrhead]

M1 is not that much taller than this stock reproduction 1968/340 intake that Mopar performance did a short run of ..here is one beside my M1

 

[12many]

Yup I need to jettison it. Just don’t know what I need to do with the PCV set up..??

That Holley doesn’t have a large PCV port nipple on the rear of the baseplate under the rear float bowl????????????

 

[Professor Fate]

You don't need the spacer, ditch it. All the necessary ports are on the carb.

 

[340inabbody]

That Holley doesn’t have a large PCV port nipple on the rear of the baseplate under the rear float bowl????????????

It dies and its dedicated to the brake booster. Can I share with the pcv?

 

[340inabbody]

M1 is not that much taller than this stock reproduction 1968/340 intake that Mopar performance did a short run of ..here is one beside my M1

View attachment 1716116430

View attachment 1716116431

Thanks this is super helpful! It’s at least an inch or two and thats huge for what I am needing.

 

[12many]

It dies and its dedicated to the brake booster. Can I share with the pcv?

My bad, I have manual brakes and use it for the PCV. I often forget most need a port for the brake booster.

 

[340inabbody]

View attachment 1716116432
You don't need the spacer, ditch it. All the necessary ports are on the carb.

Is this a pcv vacuum port?

 

[rumblefish360]

Right! Big port up front is for the PVC.
The big one at the rear is for the power brake booster.
Do not share or splice the hose together. Always run them to each respective port.

The spacer is probably helping with HP. If you remove it, you may, MAY notice a power loss. I doubt it but it’s possible. Open spacers normally add top end power. At least on single planes with open plenums. Like the M1.

 

[340inabbody]

Right! Big port up front is for the PVC.
The big one at the rear is for the power brake booster. The large port seen on the front in my picture IS from the space HOWEVER where my fat finger is a small 1/8 full vacuum line from the carb base. This is noted by Holley as the “PCV” vacuum line. Its freaken 1/8” is that ok for the PCV?

Do not share or splice the hose together. Always run them to each respective port.

The spacer is probably helping with HP. If you remove it, you may, MAY notice a power loss. I doubt it but it’s possible. Open spacers normally add top end power. At least on single planes with open plenums. Like the M1.

 

[12many]

Aren’t we talking a Double Pumper? What’s the model number? Where’s the big port on the front of the base plate?

 

[toolmanmike]

PCV Delete? The PCV discussion

 

[340inabbody]

Aren’t we talking a Double Pumper? What’s the model number? Where’s the big port on the front of the base plate?

View attachment 1716116460

Double pumper 650 CFM 4777-7 3537 there is no big or 3/8 port in the front. There IS a full manifold pressure port that 1/8” on the front near the passenger side.

 

[12many]

...there is no big or 3/8 port in the front. There IS a full manifold pressure port that 1/8” on the front near the passenger side.

That’s what I thought.

If I was out in my shop of horrors and I wanted to run a PCV and had to have vacuum for a brake booster I would either:

1) drill the back wall of the intake plenum oh about an inch or so (probably less) in the flat just below the carb flange and (preferably) thread it for an NPT fitting and install a 3/8 NPT barb. Hook the brake booster to that. Use the carb port for the PCV.

Or

2) Carefully drill the baseplate in the spot it would be at as on a vacuum secondary carb and install a 3/8” nipple.

3) research running a tee off the back port to hook both to. I’ve read of people on other forums doing it with no problems at all, and have read of others saying not to do that.

4) do a PCV delete

Me, I’d do number 1. If you ever passed the intake on the next guy could use it the same way. Or just thread an NPT plug in there.
Lots of older intakes have a threaded hole for a barb in that location, some on an intake runner.

Here’s an older Weiand single plane example, and where I’d drill and tap.

 

[340inabbody]

That’s what I thought.

If I was out in my shop of horrors and I wanted to run a PCV and had to have vacuum for a brake booster I would either:

1) drill the back wall of the intake plenum oh about an inch or so (probably less) in the flat just below the carb flange and (preferably) thread it for an NPT fitting and install a 3/8 NPT barb. Hook the brake booster to that. Use the carb port for the PCV.

Or

2) Carefully drill the baseplate in the spot it would be at as on a vacuum secondary carb and install a 3/8” nipple.

3) research running a tee off the back port to hook both to. I’ve read of people on other forums doing it with no problems at all, and have read of others saying not to do that.

4) do a PCV delete

Me, I’d do number 1. If you ever passed the intake on the next guy could use it the same way. Or just thread an NPT plug in there.
Lots of older intakes have a threaded hole for a barb in that location, some on an intake runner.

Here’s an older Weiand single plane example, and where I’d drill and tap.

View attachment 1716116474

View attachment 1716116477

Awesome post! Thank you! This really helped me a lot and I sincerely appreciate it!!

 

[mderoy340]

The M1 I have for magnum heads has the port exactly where 12many has the arrow pointing.

 

[rumblefish360]

The M1 I have for magnum heads has the port exactly where 12many has the arrow pointing.

Hey Mike!

 

[Mean416]

What's the rest of the combo like? Cam/stall/gears/heads etc.