Hello
Does anyone have any first hand knowledge of the Flowmaster Force Two crossmember back for a 73 Big Block.
Here’s what I know. Flowmaster discontinued the part number for big block and only retains the small block which is all they (Holley) and parts suppliers show.
Yet they still offer the 68/69 Big Block oddly.
Calling Holley in regards to is useless as per usual on any of their numerous groups as they just use third party tech services that just read prepared spec info.
Vet suppliers no longer have any tech support and are just now part order takers.
After enormous research I spotted a Holley statement that states the system is for both small block and big block yet again oddly is only listed anywhere as “small block”!
Bearing in mind small block uses oem 2.25in pipes and big block 2.50in.
However I found that the listed Force Two X-Pipe system listed now for small block may in fact be 2.50 pipe size. So I am believing now that Flow merely made all small and big block the same larger diameter and consolidated part numbers.
But if so I cannot understand why all listings for “only” state small block and not both since the chassis are identical cross member back.
Does anyone have any specific knowledge of.
Lastly I am only interested at this time in this system and not others such as Magna or Pipes etc…
Many thanks
Tom

 

Summit says the 817659 has 2.25" pipe and has the rectangular 70-73 tip outlets.
And the 817695 has 2.5" pipes and the round 68-69 outlets.
All the factory 2.5" pipe systems still used a 2.25" chrome outlet tip. The LT-1 even used a 2.25" inlet as well.
The 72 &73 systems used different mufflers for noise regulations, and the position of opening in the factory chrome outlet changed, for 73 only.
The GM and all available replacement rectangular tip chrome outlets are all 2.25" unless you mod it to fit 2.5" pipes. That is what I did and others as well.
Pypes does make a 2.5" rectangular chrome tip that is pretty close visually. EVT153

 

100%

 

Big block and small block manifolds are not the same. 73 sbc manifolds start out as 2” flanges and in the case of the L48. The L82 started out at the same 2” but then increased to 2-1/2” a few inches away. I believe the BBC manifolds are 2-1/2” but not in the same location.

I replaced my exhaust years ago with the Magnaflow system which was 2-1/4” until it went into an X-pipe and then changed to 2-1/2” out through the mufflers. I found Gibson sport tips that are 2-1/2” and the same size rectangles.
i did have to modify the system to fit my car so it was not a simple install.
Later I replaced the stock manifolds with true 2-1/2” manifolds from Speedway Motors so I wish the pipes were the 2-1/2” all the way.

I bought the Black tips but they do come in stainless

 

Many thanks again but as originally stated the Flow system is “Crossmember” back! If actually is 2.5 in then manifold pipes already in place are the same so the actual manifolds do not come into play.
So still hoping somebody knows from actual use
that the present Flow Foce Two listed only for small block actually does fit the big block
2.5 in system outlet tips aside.
Thanks
Tom

 

.
. I'm thinking you're going to be that guy that actually will know when your order arrives... .

 

Haha having the same thought!
Still amazing that Holley/Flowmaster just cannot simply answer such
a basic question. The bigger they get the more they consume others the less
they know and communicate.

 

Yes it would fit 2.5" front pipes. Regardless of engine.
There is zero difference in the exhaust or the car behind the trans crossmember, except for pipe diameter.
There is a pipe joint where the two holes in the crossmember are at the rear of the trans, the pipes have to go in the same place there.
There is an exhaust pipe hanger there, to keep the pipes centered in the holes, and that hanger does vary between 2.25" pipes and 2.5" pipes.
All the other differences are between the engine and the frame holes. There are several pipe variations there, at least 4 or more.

The 70-72 BBs are slightly less common, and require 2.5" pipes with the very unique square tips, so it is kind of obvious they felt it was too of a low volume item, since it was C3 specific, and did not want to deal with the available 2.25" square tips, or tool up for 2.5" chromes square tips. The factory BB mufflers have a 2.5" inlet with a 2.25" outlet. Kind of strange.

Even stranger is that all the 68-69 BBs had the smaller 2.25" exhaust from the factory, there was no 2.5" then. And that is what Flowmaster makes the 2.5" system for. But the factory looking round chromed slash tips are readily available in many sizes.

No one ever said this aftermarket stuff made sense!

 

Same as my thoughts. Outlet tips no issue actually like the look of the 70-72 better as I have on my 71 then the center outlet 73.
Thanks for the re-affirm, just being sure hadn’t missed something.