I discovered an unusual difference between an old Edelbrock dual-plane intake, & a Weiand dual plane intake. Both are from the mid 60's The p***ages are arranged differently. One has a mirror image between the front & the rear cylinders. The other one duplicates the front / rear. Has anyone ever noticed this before? I wonder which one works better....
Never had a dual plane Weiand but I ran the GM dual plane which Edelbrock seemed to have copied. On my sbc, I ran the stock GM dual plane and was happy with it. On a bbc, I ran the stock GM dual plane but milled down the center divider to kill off some torque. It worked great too.
Yes, I've noticed it on various intakes. It's still a 180 degree design, and I've run both styles on the same engine over the course of time and didn't notice any difference.
Here's my guess..each side of the carb feeds a cylinder every 180 degrees of engine rotation. Am I right?
That's how I understand it too. Both planes are divided in a way that seperates each pulse acording to the firing order. For example, the firing order in a SBC is 1-8-4-3-6-5-7-2. If you look at the intake below, each plane alternates matching the firing order. The #1 starts out on the higher top plane, then the #8 pulls from the lower plane. The #4 draws back from the top plane, & so on. (top-bottom-top-bottom-etc). I guess this is why it's referred to a 180 design.
Now this intake looks like violates the 180 design principal. If you look at the p***ages below, they don't match the firing order. #1 pulls from the the top plane, the #8 pulls from the top plane, the #4 continues pulling from the top plane. The #3 cyl finally starts drawing from the lower plane, as does the #6. The #5 goes back to the other plane. This design looks flawed. You end up having a super strong vacuum signal on one side of the carb, but the other side goes to sleep...
The intake with the standard 180 p***ages is an Edelbrock C-26 The other intake with the irregular pattern is a vintage Weiand WCV-327
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