Single-plane Tri-Power?
I've put a lot of miles on Tri-Power Pontiac engines, but all with factory dual-plane manifolds. I often wonder how a single-plane Tri-Power manifold would perform (I think I asked on this forum quite a while ago but didn't get answers). I recently noticed that the Offenhauser 360 Equa-Flow manifold (1968 era) was a single-plane and available for three 2-bbls and (I think) available for Pontiac. Anybody here ever run one?
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I had two of the earlier 64 head Offy Tri-Power Intakes.
The intakes were actually pretty good about airflow thru the short runners and divided plenum. I cut one apart one time and there were a couple of "windows" between the two side by side plenums. So they fit the 360 manifold definition. Not sure what the application was on the one I cut apart. Maybe sb chevy or sb ford. Many many years ago. The Pontiac intake I flowed on the SF 1200 flow bench, flowed about 270 cfm thru one short port. Tom V. |
Is the "360" manifold less satisfactory for everyday street use (mostly center 2-bbl) than a dual-plane manifold?
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The 360 manifold would operate like a 780 Holley 4 BBL's primaries on a single plane intake. A bit soft on the bottom end and maybe a bit more tuning required vs the calibration the Rochester Engineers put into the Factory Tri-Power 2 BBL but still not a big issue vs not running one of the things.
Tom V. |
Thanks. Merry Christmas.
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I "thought" that Offy made the 360 3-2bbl manifold because their ad in January '68 Hot Rod said "...1, 2, and 3 carb" versions. However, after January they never again mentioned a 3 carb 360 manifold, just single- and dual-quad.
So... I suspect that nobody ever made a single-plane 3 2-bbl manifold for Pontiac... and maybe not for any engine. |
I don't know if you saw this but if not here you go the only single plane Tri-Power I know of for a Pontiac
https://headsandmanifolds.wordpress....3000-7500-rpm/ |
Jack, if you cut the top off of a 64 type Offy Tri-Power Intake I believe you will see the "communication windows" that basically make it act like a dual plane 4 bbl intake but with the plenum divider removed. Both barrels of each 2 bbl carb get the same signal at the same time.
Tom V. |
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Dave Wilcox did a very nice job porting my "Barry Grant 6-Shooter" (TRI-POWER) intake but the cost was not cheap, just like the single plane TRI-POWER intakes he is selling.
Tom V. |
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Offy 360 tri power
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Isn’t this a single plane intake?
https://www.ebay.com/itm/35354808243...BoCmCoQAvD_BwE Here’s another. http://hotrodcarbs.com/store/offenha...-manifold.html |
Yes, that appears to be the Offenhauser Equa-Flow that I mentioned in the original post of this thread. I'm still wondering if anyone here ever ran it?
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Troy Patterson (tmp carbs) is making one.
https://www.facebook.com/14380661198...3501/?sfnsn=mo |
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Here are pics for those thay don't have Facebook
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Does that intake look like a modded Offy 2-4 intake?Tom
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Looks like it to me too.
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