Port intake dividers 2V what is crossflow size?

[Anonymous]

I want to weld in some port dividers along the length of my 2V inlet manifold to increase gas velocity. these will also extend into the head ports by a few inches
I need to know the internal diameter of preferably the inlet of a crossflow head or its manifold to determine the volume and how much of a division to insert.
Any help would be valued.

 

[Anlushac11]

8)

The crossflow is supposed to have darn near perfect intake and exhaust ports. Im not sure how much you could improve.

 

[Anonymous]

Sorry I probably didnt make it clear enough I want to put the dividers in the 2V manifold and use the crossflow head as a guide for the ideal size.
Since going from a 350 Holley to a 500 Holley with a smaller spacer I think I have substantually less gas velocity in the already fairly slow flowing (at lower rpm) 250 2V manifold.
It has effected drivablity in the lower rpm ranges. I have a friend with same car and engine (bit more cam) and he is having more problems than me with his new swap from a 350 to a 500.
As previously suggested in another post the the 250 2V with a 500 seem to be very sensitive to cam duration, carb ventury length and possibly carb spacers.

 

[xctasy]

To answer your question,Tim, 33 to 35 mm (1.300-1.375") for the HF-5 alloy cross-flows I've got.
'76-'79 Cast iron cross-flows had 40 mm ports (1.575").

Unlike the inagural I-V Alloy Head, the Alloy Head II cross flow intake is similar to the SOHC Pinto (Cortina) 2000 cc 2-V intake. In my opinion, the inflected angle of the 2v 250 port makes it a little difficult to fill up the base of the short turn radius. If it were me, I'd fill the intake manifold up with Devcon filler, and port miss-match to make the inlet tracts smaller than the heads intake tract. There should be a about 125 thou or a 3 mm anular mismatch. The ports were fairly close to 1.6" inches in diameter, weren't they?

Wow, funny topic, eh?. My workmate Rosco has just got a my mate Waynes old 250 2V engine form the Cortina he dumped on the motorway. He asked me this morning what carby he could fit. It's going into his early XR Pannel Van (66 Falcon utility Ranchero-type with a welded in van roof).

I told him to go the 500 cfm, but I've just remembered that there is a prospect of spit back. Aussie7Mains warned us long ago that a stock or cammed 250 2V didn't like big CFM 2-barrels.

I guess it comes down to the plenumb area being too big for good gas flow. With the bigger throttles, atomisation of the fuel air mix gets worse than with a 350 cfm. Quite why it is a problem with a bigger 25% bigger engine than the 200 cube Mustangs is a mystery to me.

Funny thing is that the 350cfm is alledgely more sensitve to big cams on engines in the 122-200 cube range, especially 9 port 202 Holdens. A 280 cam and a 350 cfm spells trouble from the people I've talked to. Fitting a 500 tends to fix the problem.

With air-flow, the idea is always to find the smallest port, carb, intake manifold, cylinder head chamber or valves to do the job. Less is more! Fuel economy, tractablity and torque are always better this way, and on the street, this is what gets sixes ahead of the pack. Thats what the Argentine Maxi-Ecconomy head is, a low port high flow version of the 2V.

 

[Anonymous]

42 mm for the 2V inlet.

I think it would be hard to use that devcon filler unless I took the top off the whole manifold.
I was hopeing to place the 5 to 7mm dividers verticle in the runners and drill through the manifold top and bottom for welding access to the dividers. From what I hear this could be done easily. Most of the runner length is square shaped which helps as well.
If anyone doesnt like the idea tell me why as this is new territory. I think I can only gain by this.
Ill keep the dividers about 30 mm back from the start of the runners and edged to try and maintain the manifolds original fuel dispersion quality.