Best Intake for a 408

[V8-valiant]

And the backstory to the 9.0-1 comp and 115 LSA was for a turbo and FI? setup?

This info and current setup will help the suggestions greatly.

Correct, the backstory is based on the turbo setup.

However the current setup consists of the block, crank and rods at this point. Everything else will be changed from the prior so that’s not relevant, because it’s getting pistons, heads, cam & intake right? It will be a completely different engine.

 

[autoxcuda]

Correct, the backstory is based on the turbo setup.

However the current setup consists of the block, crank and rods at this point. Everything else will be changed from the prior so that’s not relevant, because it’s getting pistons, heads, cam & intake right? It will be a completely different engine.

It’s not the using the details for the future build, but it gives clues in your expectations. And where you’re at now and a little of what you are comfortable with.

 

[12many]

I had a suggestion of something around 260 duration

3800 stall and a 3.91-4.10

It looks like you don’t actually have the rear gearing settled yet? Do you have the 3800 converter already?
Regardless of the gears (they are essentially the same) but a cam with 260°@.050” and a 3800 converter is really not the best match IMO. I’d go down a couple steps on the cam somewhere in the region of 250° or so, maybe 252° or 255° at the most with “that” tc and gearing.

I run 11.44@114 with a 410, 3500 TA tight and 4.10 gear. Air Gap w/750 DP, 246/[email protected]” solid roller w/TF heads all in a 3200lb deer meat freezer. I run around the street in the 2800-5500 rpm range, really only run it to 6200 at the track. There’s no need to run it up to redline on the street though.

The thing makes so much power in that rpm range and as I only do rolling acceleration runs on the street (as blowing the tires off is pointless) it digs and pulls hard.
I have a ported Victor I intend on swapping to some day. I’ll dial things in and hit the track for testing and tuning. Then I’ll see what my 60’,330, 1/8 1/4 and Mph is as compared to running the AG. I won’t be changing carbs, torque converters etc.
And if the times are better all around great. It’ll stay on. But if I loose 60’, 330’ etc I’ll put the AG back on and never look back. I’ve built for midrange power where I predominantly operate on the street.
The AG I predict will make more power in that range with my setup, will be a little quicker.
If you intend on going with a cam such as you mention and a single plane intake, I’d definitely step up in converter at a minimum.

 

[justinp61]

Missing head and cam info. But, assuming it’s a mild Eddie type deal with a semi typical 240 ish@ 50 solid camshaft…I would run the airgap, and not think twice.
better all around manifold for something with the above parameters, and the dinky vert screams airgap too.
I ran the airgap on a 360 with lots more cam and vert, and a bit less compression, and the airgap was a great fit, car ran impressively for what it was.
I doubt a Victor would run better on the street or strip in such a combo

Don, the Airgap was a good fit for your 360, the extra .42" stroke in the OP's engine really helps the bottom end.

my 418 with a ported victor doesn’t 60 much if any better than my 360 did with same cam, heads and headers and carb. 360 had airgap

going down the track you are spending virtually all your time between 3800 and 6000 rpm( again assuming non offset head and moderate cam…OP never stated)
in that range of rpm, dual plane with be more responsive, 4 inch crank or not.. I had more vert and gear and still had the result I had
this again all assumes it isn’t a light, cut up car. Mine isn’t, doesn’t appear the OP’s is either

You also had a set of headers that suited a stock build better.

The OP has a fairly light car, enough compression and gear, converter is borderline, but a single plane intake will work well for his combo.

 

[72Dart6pack]

I went this direction for my 408.

 

[V8-valiant]

It’s not the using the details for the future build, but it gives clues in your expectations. And where you’re at now and a little of what you are comfortable with.

I understand now what you’re getting at. Thank you for your input.

 

[rumblefish360]

The current cam is 241/247 @.050 with a lift of 545 and LSA of 115 but also at 9.0-1 compression. I had a suggestion of something around 260 duration and 600 lift with a 108 maybe even a 106 LSA.

Is that a modified Comp XE-HL? I had Comp modify my XE285HL to a 108.

Sorry for not being clear on what I’m looking for out of the car, I’m not sure I have a clear vision for what I want. It will be a hot street strip car. Yes I will race it, but not on a weekly basis. More like 4-6 times a year, but still want a fun street car.

No worries.

Correct, the backstory is based on the turbo setup.

However the current setup consists of the block, crank and rods at this point. Everything else will be changed from the prior so that’s not relevant, because it’s getting pistons, heads, cam & intake right? It will be a completely different engine.

Right! So, what are you looking at as far as pistons? Flat tops, small dome, hyper or forged? Where they sit in the bore is important. Zero deck, bellow or above.

It looks like you don’t actually have the rear gearing settled yet? Do you have the 3800 converter already?
Regardless of the gears (they are essentially the same) but a cam with 260°@.050” and a 3800 converter is really not the best match IMO. I’d go down a couple steps on the cam somewhere in the region of 250° or so, maybe 252° or 255° at the most with “that” tc and gearing.

I run 11.44@114 with a 410, 3500 TA tight and 4.10 gear. Air Gap w/750 DP, 246/[email protected]” solid roller w/TF heads all in a 3200lb deer meat freezer. I run around the street in the 2800-5500 rpm range, really only run it to 6200 at the track. There’s no need to run it up to redline on the street though.

The thing makes so much power in that rpm range and as I only do rolling acceleration runs on the street (as blowing the tires off is pointless) it digs and pulls hard.
I have a ported Victor I intend on swapping to some day. I’ll dial things in and hit the track for testing and tuning. Then I’ll see what my 60’,330, 1/8 1/4 and Mph is as compared to running the AG. I won’t be changing carbs, torque converters etc.
And if the times are better all around great. It’ll stay on. But if I loose 60’, 330’ etc I’ll put the AG back on and never look back. I’ve built for midrange power where I predominantly operate on the street.
The AG I predict will make more power in that range with my setup, will be a little quicker.
If you intend on going with a cam such as you mention and a single plane intake, I’d definitely step up in converter at a minimum.

On behalf of the group and the OP, I wanna say thanks for spelling out your combo. This is right about the idea in my head the OP was after. Quick, streetable and now easy to follow.

Stepping up on your example of a mid 11 combo, since it’s now a known, is easier than guessing.

 

[rumblefish360]

It’s not the using the details for the future build, but it gives clues in your expectations. And where you’re at now and a little of what you are comfortable with.

@V8-valiant

Exactly. To better help through better understanding so in the end, you’ll be happier zeroing in on a nice set up instead of some crazy combination or being unhappy with an ill performing engine/car.

Once the board members have an idea in there head of what you want and what you are looking for, the better we can get you were you want to be. The more we understand and get on the same page the better it’ll be.

 

[V8-valiant]

@V8-valiant

Exactly. To better help through better understanding so in the end, you’ll be happier zeroing in on a nice set up instead of some crazy combination or being unhappy with an ill performing engine/car.

Once the board members have an idea in there head of what you want and what you are looking for, the better we can get you were you want to be. The more we understand and get on the same page the better it’ll be.

Thank you, once explained by yourself and @autoxcuda I understand now why it was important. I appreciate everyone’s help here. Thank you!

 

[rumblefish360]

Well, on behalf of the group and myself, thanks and I hope we pass the audition!

Yea man! That’s what FABO is all about, helpin out.

 

[YO7_A66]

Hello, I’m changing up my 408 a bit and need an intake manifold. Probably 6-8 years ago the “go to” was the rpm air gap. This is a street/strip car, it’s a 408 with 10.5-1 compression, auto 3800 stall and a 3.91-4.10 gear. Looking for opinions on the best all around intake manifold before I just jump on another air gap.

V8-valiant,

I am following your thread closely since I am in just about the same situation as you, as I currently have my 340/420 in the machine shop. Mine will be a street only build and I have both the RPM (non- Airgap version) and a Weiand X-celerator ready for the build. I have not yet decided on which one to run as they are both gasket- matched/painted and ready for a last- minute install.

One thing that I will bring up is that neither one of these intake runners or the carb mount opening’s matched the gaskets that I have for the build. The information on both of these intakes show that they were designed for the 318/340/360 cu inch engine and not a 420. If you haven’t already, you may want to consider at least gasket matching the intake that you plan on using. I had to take a lot of material out of both of these intakes (runners/carb opening) to get them close to the gaskets, while these same gaskets match my heads (ported) exactly.

 

[MOPAROFFICIAL]

Hello, I’m changing up my 408 a bit and need an intake manifold. Probably 6-8 years ago the “go to” was the rpm air gap. This is a street/strip car, it’s a 408 with 10.5-1 compression, auto 3800 stall and a 3.91-4.10 gear. Looking for opinions on the best all around intake manifold before I just jump on another air gap.

Rpm/Airgap or victor340.
If you street drive or hang at/under 6000rpm, the rpm.
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[rumblefish360]

V8-valiant,

I am following your thread closely since I am in just about the same situation as you, as I currently have my 340/420 in the machine shop. Mine will be a street only build and I have both the RPM (non- Airgap version) and a Weiand X-celerator ready for the build. I have not yet decided on which one to run as they are both gasket- matched/painted and ready for a last- minute install.

One thing that I will bring up is that neither one of these intake runners or the carb mount opening’s matched the gaskets that I have for the build. The information on both of these intakes show that they were designed for the 318/340/360 cu inch engine and not a 420. If you haven’t already, you may want to consider at least gasket matching the intake that you plan on using. I had to take a lot of material out of both of these intakes (runners/carb opening) to get them close to the gaskets, while these same gaskets match my heads (ported) exactly.

View attachment 1716030177

View attachment 1716030178

In your case and if the cam is the same, super close, slightly larger, I’d run a very ported Weiand. It’s a small single plane designed a long time ago when stock heads were the only option unless you went with a W2. The big cubes will tax the small plenum and runner sizes quickly.

At 420 cubes, I’d prefer a Super Victor or a Tunnel Ram.

 

[YO7_A66]

In your case and if the cam is the same, super close, slightly larger, I’d run a very ported Weiand. It’s a small single plane designed a long time ago when stock heads were the only option unless you went with a W2. The big cubes will tax the small plenum and runner sizes quickly.

At 420 cubes, I’d prefer a Super Victor or a Tunnel Ram.

Rumble,

My cam is currently spec’d out as a 248/252 @ .050”, .410” lobe solid roller. Max rpms will be in the 6200 range.

I looked at the Super Victor and assumed that it was too much (maybe too tall) for a street ride. That is why I decided to start working on the two intakes that I had on the shelf. I was also looking at the TF Track Heat but since the deliveries are unknown and I also thought that it might be a little too big. So, I thought that the X-celerator (gasket matched) might be the first one to try. The pictures that I posted above are the X-celerator before I got started. I was surprised by how much aluminum came out of that intake to clean up the areas shown in the pictures.



I don’t want to take away from this thread, but once I get my block back from the machine shop jail, I will start a new thread on a couple of items that I have not tied down.



Thank you!

 

[Demonx2]

Rumble,

My cam is currently spec’d out as a 248/252 @ .050”, .410” lobe solid roller. Max rpms will be in the 6200 range.

I looked at the Super Victor and assumed that it was too much (maybe too tall) for a street ride. That is why I decided to start working on the two intakes that I had on the shelf. I was also looking at the TF Track Heat but since the deliveries are unknown and I also thought that it might be a little too big. So, I thought that the X-celerator (gasket matched) might be the first one to try. The pictures that I posted above are the X-celerator before I got started. I was surprised by how much aluminum came out of that intake to clean up the areas shown in the pictures.



I don’t want to take away from this thread, but once I get my block back from the machine shop jail, I will start a new thread on a couple of items that I have not tied down.



Thank you!

I was told the Super Victor and the 850 DP carb would be sluggish on the street. I assure you it is anything but sluggish! It is highly responsive and lays your ears back mighty quickly. What I cannot say is whether it is better or worse than the Air-Gap. But honestly, with how it runs now, I'm not much inclined to make a swap to find out. (Well, ok, nothing occurs now anyway...it's wintertime!!)

 

[rumblefish360]

Rumble,

My cam is currently spec’d out as a 248/252 @ .050”, .410” lobe solid roller. Max rpms will be in the 6200 range.

I looked at the Super Victor and assumed that it was too much (maybe too tall) for a street ride. That is why I decided to start working on the two intakes that I had on the shelf. I was also looking at the TF Track Heat but since the deliveries are unknown and I also thought that it might be a little too big. So, I thought that the X-celerator (gasket matched) might be the first one to try. The pictures that I posted above are the X-celerator before I got started. I was surprised by how much aluminum came out of that intake to clean up the areas shown in the pictures.



I don’t want to take away from this thread, but once I get my block back from the machine shop jail, I will start a new thread on a couple of items that I have not tied down.



Thank you!

Woooooo, stout cam for the street!

Looking forward to your build thread. Carry on!

 

[Bobzilla]

I was told the Super Victor and the 850 DP carb would be sluggish on the street. I assure you it is anything but sluggish! It is highly responsive and lays your ears back mighty quickly. What I cannot say is whether it is better or worse than the Air-Gap. But honestly, with how it runs now, I'm not much inclined to make a swap to find out. (Well, ok, nothing occurs now anyway...it's wintertime!!)

Is that Super Victor all stock or was it properly ported?

 

[justinp61]

I was told the Super Victor and the 850 DP carb would be sluggish on the street. I assure you it is anything but sluggish! It is highly responsive and lays your ears back mighty quickly. What I cannot say is whether it is better or worse than the Air-Gap. But honestly, with how it runs now, I'm not much inclined to make a swap to find out. (Well, ok, nothing occurs now anyway...it's wintertime!!)

Probably by the guys who have never done it but read on the internet that you can't.

 

[rumblefish360]

Well you know for a fact the internet experts are never ever wrong, right?????

 

[glockr]

Well you know for a fact the internet experts are never ever wrong, right?????

"Wrong is - wrong is right - wrong is right
I'll never believe all the crap, all the crap they say
Wrong is right, wrong is right, wrong is - wrong is ..."

 

[Demonx2]

Is that Super Victor all stock or was it properly ported?

Hmmm...."properly ported." Maybe a loaded question for some. Easier for me in my case as it was not ported. Intake gaskets set against it showed the runners to be central to the port openings so I thought let's first see what it looks like on the engine. It was set in place on the engine and I was amazed to find that the ports aligned just about perfectly to the ports in the head. That manifold is open and tall enough to see down each runner and I found there to be NO need to touch it. Yes, I was surprised by this as I wanted to start making alum chips so I could claim I improved it. But that would have done nothing in this case (and maybe I would have hurt it!). Now I know others have said/shown that cleaning up the runner entries and the roof radius would also help it. This was not done but certainly could still be done. I dunno - I seemed to have gotten a good casting for some reason.

I think the rest of my hardware (mainly the Eddie RPM heads) are at the low end of the capability of this manifold so I probably don't tax it much if that makes sense. When I get more cyl head or cam, perhaps that would be a good next step!

 

[rumblefish360]

Well said.

 

[fishmens67]

Super Victor OOTB flow # is around 290cfm, full port 325cfm or so.
OOTB should match well with OOTB or ported standard head.

 

[Bobzilla]

Hmmm...."properly ported." Maybe a loaded question for some. Easier for me in my case as it was not ported. Intake gaskets set against it showed the runners to be central to the port openings so I thought let's first see what it looks like on the engine. It was set in place on the engine and I was amazed to find that the ports aligned just about perfectly to the ports in the head. That manifold is open and tall enough to see down each runner and I found there to be NO need to touch it. Yes, I was surprised by this as I wanted to start making alum chips so I could claim I improved it. But that would have done nothing in this case (and maybe I would have hurt it!). Now I know others have said/shown that cleaning up the runner entries and the roof radius would also help it. This was not done but certainly could still be done. I dunno - I seemed to have gotten a good casting for some reason.

I think the rest of my hardware (mainly the Eddie RPM heads) are at the low end of the capability of this manifold so I probably don't tax it much if that makes sense. When I get more cyl head or cam, perhaps that would be a good next step!

Thanks for the detailed response. I don’t personally know anybody running the Super Victor. Always like hearing how things are working in the real world.

 

[67autocross]

The Super Victor needs a pile of work over an airgap or even a Victor… mot an out of the box deal in my opinion….