Offenhauser Dual Port 360 - run it or scrap it?

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1MeanA

1MeanA

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I'm building a stock 340 and have this Offy manifold. Is it worth trying? Its an odd thing.

- 68 4 speed cam
- hp manifolds
- real 10:1 compression
- 2.02 'O' heads
- 4 speed
- street use only
- carb - probably AVS2 650

IMG_2003.jpg
 
Sell it and buy a know good intake that has been proven on Dyno tests.
 
Is this the funky divided port intake? I hear they are OK on stock builds. Yours looks like a good candidate for it, I'd try it before I sold it.
 
I used one many moons ago 727 g-60-14 3.23sg 650 vac sec
Did feel like it had better part throttle response
pulled good to 5500 in drive prolly 50 times or more i went single plane for the spray
I would try it
 
I also ran an Offy DP360 on my '69 Swinger 340 back in the early '70s with good success. Just like the previous post I also had a 727, G60-14s and 3.23 gears.
I later changed to 4.89 gears and had the 727 built as a reverse-pattern manual shift. The cam I had demanded more carb so I ended up running a Holley 850 double-pumper. My Dart had a lot of success on Whittier Blvd. back then.
Give the intake a try and see what you think.
You can always sell it if you don't like it.
 
honestly, I'd gasket match that to the heads and run it. with the AVS it should have great off idle characteristics and good midrange with crisp throttle response.

considering street use and backed up by a 4spd, it should be a nice little combo.
 
They are interesting intakes. I've never run one. But I can tell you this from the rest of the Offenhauser intakes I HAVE run. They do what Offenhauser said they do. So it wouldn't surprise me if it works pretty good.
 
I bought one of those a few years ago with a spreadbore flange, for a build I had in mind. The build fell thru, but I still have the intake. Not sure what I'll do with it yet, but sooner or later Ima gonna try it on something!
I think you should try and report back, and either save me the work, or encourage me to install it in place of my Airgap, lol.
 
Thanks for the input. Nobody is saying that it is terrible so I'll give it a shot unless I run across a cheap RPM Performer.
 
1MeanA said:
Thanks for the input. Nobody is saying that it is terrible so I'll give it a shot unless I run across a cheap RPM Performer.
Click to expand...
Nobody is saying it's a terrible manifold because it's not. That manifold was known for off idol right on up through the RPM range. In a sense it is two manifolds in one.
If you don't want it I'm interested in it.
How about that port picture?
 
Jadaharabi said:
Nobody is saying it's a terrible manifold because it's not. That manifold was known for off idol right on up through the RPM range. In a sense it is two manifolds in one.
If you don't want it I'm interested in it.
How about that port picture?
Click to expand...
I guess technically, it's a 100% true dual plane intake. Would you say that?
 
I agree with above, you have it, you can try it for the cost of gaskets, and some wrench-turning. I would rather see it on a 318 with 2.76 gears, trying for gas mileage.
I suspect it might work okay on the bottom end, and off idle. I also suspect a RPM airgap will absolutely murder it, everywhere.
 
on my spreadbore Dualport
I once had in mind to max the cylinder pressure, and run the small primaries on 87 gas, and the secondaries on 91. But neither the TQ nor the QJ, have separate bowls. I bet it wouldda made great fuel-economy tho, and decent enough power for a streeter. And around here, 87 is about 80% of 91, so that is a very significant savings on a Daily Driver..
Oh if somebody only made drop-in high compression pistons for the 318, for reasonable money. or longer rods I guess.
Speaking of which; how cool would it be to have adjustable length rods? I mean you could take any old smog-teen and just crank the pistons up to where you need them to be, and bolt it all back together; how cool would that be.
But if you went too high, no problem, just crank the rods down a bit.
I know, I know, that would come with it's own set of problems...... still ............... it's fun to think about.
 
The Offy Dual Port comes under the category of......'It sounded like a good idea at the time'.
 
My brother put one on his new 1972 Challenger 340. Many years later when he rebuilt the 340-he put the stock intake back on. I didn't realize it was that dual-port till I seen it laying there. He said that intake wasn't near as good as the stock 72 TQ intake.
 
I'd try it. If it doesn't work, you're just out a set of intake gaskets and a little time. Offy made some interesting stuff. I have a dual 1-bbl modified to run dual Webers sitting on the shelf for a Slant Six build (if I ever get around to it) and just picked up a dual quad for a 318 build I'm going to start as soon as I figure out what pistons I want to put in it.
 
kdeboy said:
as soon as I figure out what pistons I want to put in it.
Click to expand...
might I suggest; lol
This is just a question;
Small Closed-chamber Alloy heads, a solid lifter cam, and something like the tall KBs that need to be machined, to set the cylinder pressure to around 185psi. This should run on 87 gas.
 
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