Low Profile Single Plane Intakes

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Garrett Ellison said:
I guess your right on that. I was thinking since he already had one, though...
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That does make a difference. I was thinking of using the 360 on my 440 ritter build while I assemble the Fuel injection system. I ran one on a 400 bb years ago with a 484-284 purple shaft a 3310 and 3.91 gears. It was amazing.
 
Dmopower said:
Isn't the dual port the same as the 360*?

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No. The Dual Port is exactly what is sounds like. There are actually 16 individual ports that are made by splitting the ports with a horizontal wall. Although the Dual Port is made off the 360, the standard 360 is not a Dual Port. Confusing enough? Here is the Dual Port.
DUAL PORT.jpg
 
360* means it's a single plane. Offy never made a dual plane which are 180*.

The Dual Port has to separate plenums, 2 sets of runners. They don't join until you get to the port. It's a low to mid range intake for torque and MPG's. Mine is a spreadbore flange. I put a Thermoquad on it for the small primaries. When it got so sloppy on the throttle shaft I swapped to a '86 or '85 Mopar Quadrajet.

I have seen EFI 4 cylinder Fords with dual port intakes. Long rams. There is a valve on the top that opens the bigger port.
 
From Summit's website probably verbatim from Offy,
Offenhauser Dual Port Intake Manifolds

"Offenhauser Dual Port intake manifolds feature completely separate runner systems for the primaries and secondaries for more power across the rpm range. At low-load, the primaries feed the air/fuel charge through the smaller bottom passages at near sonic speed, improving power and efficiency. When the secondaries open, their charge goes through the bigger, cooler upper passages. Then, in turn, it is rammed into the cylinders when it encounters the high-velocity mix from the primaries. The results are better fuel economy and a 15-30 percent power increase
across the entire rpm range."

That divider will probably cut down on flow. The velocity of the primary is a good idea for off idle to cruising speeds.
 
Wow, lot's of experience coming through! I appreciate all the thoughts and advice. I'm wondering now if the Dual Port on my shelf might be interesting in combo with the 308 heads on a 4" crank. I suspect it won't want to rev high but the throttle response and torque might be crazy. In the light Valiant with tall gears that should be interesting. Definitely the other end of the spectrum from a genuine 273 Commando.

Like I said at the start, I'm departing from my approach since the 70's of running traditional racer modded smallblocks. Something interesting but mild sounding in a mellow looking street car suits my more relaxed old age, but I can't resist packing a big stick while walking softly.

Thanks everybody!
 
I ran my 360 in my van with that 318 intake for 175,000+ miles. The van is allegedly sold. (Haven't got all my money yet.) Intake and carb are staying with me.

I am willing to bet a set of home ported #302 closed chamber 318 heads with big valves would add to the romp'n stomp'n torque.
 
Valiantjim said:
Like I said at the start, I'm departing from my approach since the 70's of running traditional racer modded smallblocks. Something interesting but mild sounding in a mellow looking street car suits my more relaxed old age, but I can't resist packing a big stick while walking softly.
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Same here- went from "in your face" no holds barred builds; to my current more comfortable, under the radar builds. And I think I'm having much more fun this way, too! More relaxed, yet more "sneaky" fun.
Heck, I've even started to run automatics now instead of my previous "stick only" attitude! (I guess my old joints are catching up with me...)
 
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Professor Fate said:
Same here- went from "in your face" no holds barred builds; to my current more comfortable, under the radar builds. And I think I'm having much more fun this way, too! More relaxed, yet more "sneaky" fun.
Heck, I've even started to run automatics now instead of my previous "stick only" attitude! (I guess my old joints are catching up with me...)
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I'm with you there.
 
My oldest brother ordered a new 1972 Challenger Rallye 340 back in 71. I was just a little kid, sometime when it was fairly new, he put one of these Offy Dual Ports on his 340, they made them with the spreadbore flange so he used his Thermoquad. I just thought it was cool that he put an aluminum intake on his car. Fast forward many years-when he was freshening up the 340, he put the stock intake back on. That was when I had a chance to inspect the Dual Port. I asked him how much of a difference it made over the stock intake. He said it didn't run as good as the stock TQ intake does. Might be ok for mileage.
lemondana said:
I would not use the Offy Dual Port.
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Decision made. I added in the cost variable and concluded I'll use KB quench pistons for a 360 at 10.5 compression with my 308 heads and run a Holley Street Dominator that I have. It matters too that the lowest cost suppliers all seem to be out of stock for their 4" stroker kits. I also have a custom hyd/roller cam that was made for a 360 with restricted intake/exhaust manifolding. Painted up Industrial Red with 273 Commando valve covers and air cleaner it should look very mild under the hood of the '66 V100, especially with the single exhaust that I still intend to get tricky with. The car is very basic, all manual except the 904, even factory radio delete.

I was really tempted to go all out with the disguised 408 but I've learned over the years to stifle the impulse to max out.

Thanks everyone and I hope we all learned a bit, I sure did.

I'll let the forum know how it all turns out.
 
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