Engine and Transmission Tech

Hi,

Does anyone know the flow specs for this intake and the port dimensions for this intake at the head?

also what about max porting size (at the head) and ported flow?

Thanks,

Robert

FWIW, this manifold has identicle port size, to their sp. 4bbl manifold. I can measure one. They are easily ported to 64'/ 300 Buick size. They can use IDF webbers, with an adaptor. Cleaner is to weld-modify, and machine. No coolant around the carbs, make this easier.This manifold is simple, to weld-mod., for a 6V-71 roots type blower. No flow spec's on this manifold, have been published. Offy was once prominent, in speed parts, un-marred by new designs, for last 40-50 years ? Good Luck, roverman.

I don't know any port or flow info for these manifolds.
But the 2 bbl carbs that bolt to this manifold are the old Stromberg 97. / Holley 94. style.
These type of carbs are a very old design. From the late thirties if memory serves.
And they only flow around 150 cfm each. Some claim 175 cfm but have never been able to prove it.
And besides 2bbl's are rated at a higher pressure drop than 4bbl's. Aprox 40% difference.
So for direct comparison, 2 x 175 - 40% = 210 cfm.
Even the small holley 390 4bbl. flows better.
So from a performance standpoint a different manifold might be better.
From an aesthetic view the twin 2bbl manifold is a good looker.
If you want to use it then, check out Moon's 97 style fuel injection.
The throttle bodies bolt right on and flow 225 cfm each.
And it uses the SDS electronics which are dead easy to tune.

Cheers
Fred

Fred, The're "slightly" newer, Rochester "2G's". Largest version was on 394" Olds ? Obviously, IDF's would flow more, but more work to mount. If I could only post how sweet, the 6V-71 looks on this manifold..... roverman.

Art, The Pontiac 389/400 had the larger Rochester 2G also. You would also need progressive linkage for the larger carbs.

The problem is the 2G has a 4 bolt flange. The 97's and 94's only have three. And the bore spacing is different.
So modifying the manifold is a necessity.
The 2G is probably easier and cheaper to source though. Millions of then came on GM vehicles, buses, stationary engines, etc.
If you really want to use a 2G have a look at the marine version.
Much bigger than the puny automotive version.
Heavily modified ones top out at 650 cfm or so.

Cheers
Fred

Fred, I agree on modding the older manifolds but, you must not be aware the Offy dual 2 barrel is available in the 4 bolt Rochester pattern. Later issue and brand new.

Nope, wasn't aware of that Jim.
But thanks. I'll stick that in the old memorybank.

Cheers
Fred