273 Intake 4 bbl Conversion

-
Dart5150

Dart5150

Well-Known Member
Joined
Dec 30, 2023
Messages
49
Reaction score
60
Location
Chapin, SC
So I have an opportunity to buy a 4 barrel intake, and the seller states that it's for 318, 340, and 360 ci V8's. Can this also be used on a 273? Also, what is the 'go-to' 4 barrel carb for the 273? And are there any linkage issues and/or challenges? Any other considerations if making the swap?

intake1.jpg


intake2.jpg
 
As far as an intake goes, it will fit, but what you are really looking for is an LD4B.
Port size is smaller for the 273/318.
 
CRUZE 418 said:
As far as an intake goes, it will fit, but what you are really looking for is an LD4B.
Port size is smaller for the 273/318.
Click to expand...
Okay, thanks. Dumb Mopar rookie questions, I assume the LD4B is a 4 barrel intake for the smaller V8's. Is there a way to ID the one pictured?
 
Dart5150 said:
Okay, thanks. Dumb Mopar rookie questions, I assume the LD4B is a 4 barrel intake for the smaller V8's. Is there a way to ID the one pictured?
Click to expand...
What's the number on it? I can barely read it.
 
Dart5150 said:
So I have an opportunity to buy a 4 barrel intake, and the seller states that it's for 318, 340, and 360 ci V8's. Can this also be used on a 273? Also, what is the 'go-to' 4 barrel carb for the 273? And are there any linkage issues and/or challenges? Any other considerations if making the swap?

View attachment 1716200025

View attachment 1716200026
Click to expand...
You have a lot of questions there and some variables with our answers.
The intake will work on a 273 as long as the heads are 66 and newer. 64 and 65 heads had smaller bolts and they were at a odd angle. the early heads has 5/16" bolts where the 66 and newer were 3/8". The mis match between larger ports and the smaller 273/318 ports isn't a real issue.
The go to carb size is 500-650 cfm. With a original 2 barrel engine I would find one on the smaller size. Depending on the carb you use and whether your car is a auto or manual transmission, there will be throttle linkage issues and transmission kickdown linkage issues you will need to address.
 
Last edited:
Dart5150 said:
Okay, thanks. Dumb Mopar rookie questions, I assume the LD4B is a 4 barrel intake for the smaller V8's. Is there a way to ID the one pictured?
Click to expand...
toolmanmike said:
What's the number on it? I can barely read it.
Click to expand...
It looks like it may be a #3614025 which is a 1972 A,B, and E body 340 manifold. It will bolt up to the 66 and newer small block LA heads.
 
toolmanmike said:
It looks like it may be a #3614025 which is a 1972 A,B, and E body 340 manifold. It will bolt up to the 66 and newer small block LA heads.
Click to expand...
toolmanmike you've given me a lot of good info and some things to consider. Much appreciated!
 
toolmanmike said:
You have a lot of questions there and some variables with our answers.
The intake will work on a 273 as long as the heads are 66 and newer. 64 and 65 heads had smaller bolts and they were at a odd angle. the early heads has 1/4" bolts where the 66 and newer were 5/16". The mis match between larger ports and the smaller 273/318 ports isn't a real issue.
Click to expand...
64-65 intake bolts are 5/16" and 66 and newer are 3/8".
 
That intake will work, but it is best with a Thermoquad carb. You should also use a 340 throttle cable bracket, an air cleaner for the carb you use and some form of kickdown if you have an automatic transmission. What wrench fits your intake bolts on the 273? 1/2 or 9/16?
 
The picture of his car is a 64 Dart, so that implies the early intake & heads. Before I was cognizant of this issue, I inadvertently installed a pair of early heads on my 67 Commando 273. Because the angle the intake bolt holes are drilled into the heads is different, the intake did not seal — it sucked oil out of the valley into the cylinders, resulting in clouds of smoke and completely gunky valves. I strongly recommend not using a 318/340 intake on the early heads.
 
mvh said:
The picture of his car is a 64 Dart, so that implies the early intake & heads. Before I was cognizant of this issue, I inadvertently installed a pair of early heads on my 67 Commando 273. Because the angle the intake bolt holes are drilled into the heads is different, the intake did not seal — it sucked oil out of the valley into the cylinders, resulting in clouds of smoke and completely gunky valves. I strongly recommend not using a 318/340 intake on the early heads.
Click to expand...
That will happen. There have been a few here on the site say that you can hog out the bolt holes and use some angled washers. That may work for some but I sure wouldn't.
 
Dart5150 said:
So I have an opportunity to buy a 4 barrel intake, and the seller states that it's for 318, 340, and 360 ci V8's. Can this also be used on a 273? Also, what is the 'go-to' 4 barrel carb for the 273? And are there any linkage issues and/or challenges? Any other considerations if making the swap?

View attachment 1716200025

View attachment 1716200026
Click to expand...
If you have the older heads the manifold can be redrilled at an angle to fit.
 
Rev.Mopar said:
If you have an early 273 and don't want to mess with any mismatch, I have an early 273 HP intake with the funny angle bolts. 273 and 318 heads have smaller intake ports that the 340 and 360. I also have the correct (though modified but very streetable) AFB with the smaller bolt pattern. If interested, PM me.
Click to expand...
Send the OP a personal message. Let's not sell parts on tech threads.
 
You must log in or register to reply here.
-

Back
Top