Single 2 Barrel down draft Manifold options

[spmdr]

I picked up a new China Repo Weber 38/38 carb

and started to look at manifolds.

I have 2 different OEM manifolds.

and the newer Alpine Innovations part is looking good.

But what are the performance differences, really?

Here are the two OEM manifolds:




The straight runner manifold has casting # 1980958

The W shaped manifold has casting # 1981124

And the Alpine Innovations:



I need to mod the OEM manifolds for the Bigger 38/38 carb,

But, do I cut out the web between the holes? Hmmmmm.

How many have "Been there and Done that" ( had their way with the manifold, good or bad results ) ??

DW

 

[spmdr]

Pierce Manifolds sells this one and I think

it is the same one Sunbeam Specialties sells.

DW

 

[husky drvr]

Wild and crazy thought. Since you aren't using a progressive carb, why don't you fab your own true two plane manifold? #1 and#4 to one throat(inner) and #2 and #3 to the other(outer). Small balance passage between two sides of plenum.

If not, then I vote for the AI unit.

Just one more complication,

 

[DanR]

The W shaped manifold has casting # 1981124

I would suggest this as my first choice.

 

[alpine_64]

Dan.

The factory W manifold I would suggest is better than the pierce one. The throats for the runners intersect at the plenum so the pickup should be more even than the seperate. The W was developed for the later rootes cars...sceptrer etc... I had one once.

The Alpine innovation one is based of the design of 2 period manifolds one from Italy (Magnotessi sp?) And one from new Zealand that used this style arc design. The theory being to ensure the outer cylinder got equal fuel distribution.. the guys in the UK claim many things about its design and evolution.

There was a good article years ago by Carl Christiansen about the various manifolds and their performance.. I had a copy but it's at home... And a bit far away for now.

As for the bridge .. given you're going for a synchronous carb and large throat... I'd bore the intake to a single throat especially on the W manifold