400 4-barrel intake question

Daniel Romero

Member
Joined
Nov 13, 2016
Messages
105
Reaction score
92
Location
Southeastern Colorado
I’m finally going to have my mechanic swap my two-barrel carb to a four-barrel on my ‘73 Fury III. I’m going to be the one looking for a 4B intake manifold. I’ve decided I want to hit up the junkyards instead of going aftermarket. As far as interchangeability is concerned, will an IM from any year 400 work? Will an IM from a 383 work? Any years of the 400 I should avoid? I’m undecided on a carb, as far as if I’ll go with Holley or Edelbrock. Suggestions? Going on an essentially factory engine but mild performance improvements may come. At least till a rebuild is necessary but it’s currently only at 85K miles so hopefully I have a while before I have to start thinking about that.
 
Any B motor intake will fit including 383. yes they are friggin heavy!
Depending on your local smog laws you may have to use an intake with an EGR
If you can run without an EGR you can run a 68-70 "301" casting 383 intake with an Edelbrock carb.
Any 67 or older intake I do not recommend since the runners and ports do not flow very well compared to later intakes.
72 400 4bbl intake has the spread-bore for the Thermoquad but no EGR.
74 78 intakes are also spread-bore and have EGR.
You can search for a spread-bore carb to use on the later intakes or use a base adapter.

Personally,I went through this myself and ended up installing the Edelbrock Performer dual plane manifold. I ground off the name and painted it engine color.
Sure an Edelbrock intake may cost a few hundred but will save a lot of headaches later.

Make sure when you score the intake,get the 4bbl throttle cable and kickdown linkage and throttle bracket--all different from 2bbl.
Any slant six throttle cable will work since they are longer than 2bbl. V8.
Use the Felpro one piece turkey an gasket and block the heat crossover.
Use an electric choke.
Hope this helps.
boab september 2017 001.JPG
 
The later the intake the bigger the volume. The earlier the intake the sharper the bends.
I would use as late as you can get.
The square to spread board adapter works better in that direction than spread to square direction.
 
If you want to add something different, I have an Edelbrock 6-pack intake for a B motor I'm not going to use. It's a lot lighter!! It's still in the original box and has never been bolted to an engine. I want $350 for it - cost around $450 new. The expensive parts are the carbs and other needed items.
I really like multi carbs. I ran 2 4's from a '58 Golden Commando Fury, 350ci. for years on a 383hp. The sound of the carbs at "full song" and performance were outstanding!!
 
Cbarge has some good advice. The bottom line, if you want to run a spreadbore carburetor, then use a 400 intake. If you want to use a square bore carburetor (all barrels the same size), then use a 383 intake.

Seriously, you should check your local craigslist since you might find an aluminum intake for $50-$100
 
Just to clarify...(RB) 413 and 440 intakes will not fit. FYI

The intakes are of the "dry" type (no coolant flows through them--just air)
and used aftermarket ones are readily available.
Along with Craigslist as mentioned,check out any local Mopar clubs and speed shops.
 
As for the carb, IF you want a "factory carb look", the BEST thing is the Street Demon with the phenolic bowl option. Looks so dang close to a factory TQuad it's unreal (including the internal guts!!). It will fit both a squarebore and spreadbore manifold, so that part doesn't really matter, plus it can have an electric choke too. Be sure to get the thick OEM-style base gasket, for which ever style of carb you end up with. They are in the Holley carb catalog. Possibly at NAPA, too, if you know the application you need one for.

IF you decide to use the heavy (read that h-e-a-v-y) cast iron factory intake, the 1973 (maybe the CA-spec '72s) intakes had "floor jets" in the base of the manifold plenum. These were a restriction that allowed exhaust crossover gases to intrude into the intake manifold, in a someaht controlled manner, for EGR. Some had brass towers over them, possibly. The old-line Chrysler service manager called them "calibrated vacuum leaks". In later years, they had a dedicated EGR valve and actuator.

All thing considered, a new/used Edelbrock Performer might be the total best way to go. A newer version of the original DP4B 4bbl intake from the late 1960s, very possibly. I'd suggest you use the Fel-Pro 440 6-Pack application paper gaskets to go with the metal breast-plate gasket, myself. Better to keep the metal from directly contacting the aluminum intake, for best results.

As mentioned, there are lots of little things that are different on the 4bbl carb linkage/kickdown rods than you might suspect. Get EVERYTHING from the donor vehicle, in that respect.

Talk about it with your installation shop people, too, so everybody knows what needs to and will happen. That "same page" stuff.

DO expect to be ready for a bit of carb re-calibration on any aftermarket carb, even if it seems to work well as is. Do NOT expect normal driving to feel that much different than with the 2bbl, until you "hit passing gear" where the added flow of the 4bbl will come into play.

Depending upo0n local emission state inspection regulations, you might need to also scout a snorkel air cleaner for a 4bbl car, with the heat stove item in the snorkel. The correct model year can be a bit pricy, but if you're flexible, the cost might come down a bit. Only thing is the cosmetics of the situation and how you will handle the "that's not right for that car" comments.

Enjoy!
CBODY67
 
Will a factory dual snorkel fit on a demon carb? I’ve got a 400 2bbl conversion myself with a 75 or 76 intake (can’t remember) on my 72. My TQ just gave me the best summer I’ve had in a long while even tho my carb guy who repaired my bowl 2 years ago says I’m on borrowed time. I’ve never been completely satisfied with the mechanical choke situation either. Different style than 72 factory.
 
Will a factory dual snorkel fit on a demon carb? I’ve got a 400 2bbl conversion myself with a 75 or 76 intake (can’t remember) on my 72. My TQ just gave me the best summer I’ve had in a long while even tho my carb guy who repaired my bowl 2 years ago says I’m on borrowed time. I’ve never been completely satisfied with the mechanical choke situation either. Different style than 72 factory.

If you mean the Street Demon, yes. I'm running the 625 unit (on an Eddy Performer 440) and LOVE IT. Tip-in response is instant, and WOT is great, because a 440 at 5000 rpm only needs about 555 CFM for our heavy, lazy, 3.23-geared street cars. You'll need to buy their correct carb throttle/Kickdown stud, FYI. The OEM unit doesn't work.

If you use a high-rise manifold like the Perf 440, you'll need to modify (raise) the throttle cable clamp "upright" as you might be able to see in this pic. The cable needs a level shot towards the throttle stud, as the secondary quadrant link intrudes on that area when you're at about 3/4th throttle. Somebody sells a raised throttle bracket, IRRC.

Note: the clamp and nut are now proper natural finish. And that red choke wire in the background is going away. Show points! [NOT]

OIKQ4817.JPG
 
Last edited:
See that rounded silver thingy on the Demon unit under the cable protective housing in the pic from my previous post, above? That rotates upward to open the secondaries when given the throttle, and can interfere with your cable. The cable needs to be horizontal to the linkage stud as you can see here. I imagine the carb is set up out of the box for Chevy linkage. Isn't everything?

Here's a comparison:

Stock height bracket using AVS carb

IMG_0350.JPG


Modified height after welding in an extension for Demon

IMG_3241.JPG
 
Last edited:
If you mean the Street Demon, yes. I'm running the 625 unit (on an Eddy Performer 440) and LOVE IT. Tip-in response is instant, and WOT is great, because a 440 at 5000 rpm only needs about 555 CFM for our heavy, lazy, 3.23-geared street cars. You'll need to buy their correct carb throttle/Kickdown stud, FYI. The OEM unit doesn't work.

If you use a high-rise manifold like the Perf 440, you'll need to modify (raise) the throttle cable clamp "upright" as you might be able to see in this pic. The cable needs a level shot towards the throttle stud, as the secondary quadrant link intrudes on that area when you're at about 3/4th throttle. Somebody sells a raised throttle bracket, IRRC.

Note: the clamp and nut are now proper natural finish. And that red choke wire in the background is going away. Show points! [NOT]

View attachment 240341

Screenshot_20181122-012353.png
 
Back
Top