Cast iron 4bbl intake differences between 340 vs 360

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MObarracuda

MObarracuda

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I have a 1980 4bbl intake casting number 4173915 and I have some questions for FABO members. The pictures of the red intake are the 360 and the silver intake is the 340. Here are my questions:

1) Are there performance differences between the 340 and 360 4bbl intakes?
2) why are the 4bbl holes in a 340 round and the 360 slotted?
3) I a missing a part that covers the exhaust crossover. Since this intake is from the 80's is it a smog accessory. Can you tell me what it is and is their a part number for the part or a plate that will cover the hole? (See picture)
4) What is the boss inside the red 360 intake? (See picture)

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IMG_0047.JPG
 
For some reason the 340 intake reference picture didn't upload. It is attached for your convienice

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IMO, those two intakes are equal. Now, had you referred to the 71 TQ intake, then I would say it had the edge.
 
Just so you know, the later year 340's didn't have the 4 hole intake. They had the same style as the 360 without the EGR valve.
 
Is there an aftermarket EGR delete part that still allows exhaust flow or should I fabricate a plate that allows hot exhaust to flow in place of the EGR valve to close the hole?
 
1; Between the two intakes, the spread bore has the edge. And *I think* it is due to the TQ carb on top. As delivered.

2; If you mean where the carb sits.....
The 4 hole is designed to help torque. Think 4 hole spacer.

3; That spot is for the EGR valve. Just use a EGR valve and proper gasket. The EGR valve is only open when there is vacuum tonit. No vacuum? Then the valve is closed.

4; That is a floor jet. It has a passage way under it that leads to the EGR valve. Plug it flush. Seal the other one on the other side.

Your last post, post #5. Read the above last two answers I gave.
 
Thank you all for sharing your advise. Floor jets come out tomorrow.
 
both equally good intakes. the 1970 340 intake is for a square bore carb, like an afb or avs or most holley, I had one stock on a 1970 340 Duster and it had A. C. the 360 intake is for a spreadbore carb, like thermoquad or quadrajet and some holleys. you can make a blockoff plate for the e.g.r.
 
While both intakes are good performers, one would be limited by carb size by the older 340 intake. OEM 340 carb wasn't big, 625cfm perhaps? Might find a 750 that would work without an adapter or opening up the holes. (Adapters usually restrict cfm.) You're limited to a bolt-on spread bore with the later 360 intake, but Thermoquads flow between 750 & 850 (depending who you talk to.) and perhaps a bigger spread bore may fit as well.
 
As Locomotion was saying, the;

AFB's were 600 or 625 depending on who you speak with.
AVS carbs were factory rated at 630 small, 750 big. But the 750 may not fit the holes in the intake.

The TQ's are commonly rated by what Carter marketed them as. 800 & 850. They did flow a little less. There is a thread around here by a passed on member. Small primary @ 737cfm, large primary @ 787cfm.
Carter did have actual after market TQ's. Small primary electric choke models & 2 manual choke race units. The QJ is also a possible replacement.

Your OE, TQ intake can use any stock or electric choke model. The only hard part is tuning kits. You can purchase individual jets and rods. A little pricey. But available. I bend AFB rods 3/4 of an inch shorter.

Also use a thick base gasket to keep heat out of the carb. They operate best with a thick gasket.

For the EGR, you must find the high heat gasket to keep it sealed off.
 
You can bolt a Holley spread bore on thatvTQ intake as well
 
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