when i got my offy manifold it came with the top, it looks like part #5170($31.91) that was a few years ago. the manifold in the parts catalog shows the top with the manifold.

The product description for the 90° Square Bore Adapteris as follows:

The conventional installation of 4bbl carburetors on slant six engines is with the primaries facing the front of the car. The secondaries would then be facing the rear of the car. While cruising on the highway, this arrangement should not pose any problem with fuel distribution. However, when accelerating, the front 3 cylinders would receive proportionately more fuel from the accelerator pump and the rear 3 cylinders would starve for fuel. Unless the rear barrels of the carburetor are completely identical to the front barrels in every way, the fuel mixture received by the front 3 cylinders will be different than the rear 3 cylinders whenever the secondaries were open.

This adapter corrects this problem by aligning the throttle shafts with the engine so that the all cylinders receive a much more even distribution of fuel. We recommend mounting the primary barrels farthest away from the engine for three reasons:

1. The idle mixture and speed adustments are easily accessible from the left side of the car.
2. The primary barrels are roughly the same distance from each of the cylinders.
3. The accelerator pump shot is evenly distributed among all cylinders. Orienting the carburetor with the primary barrels closest to the engine ensures that cylinders 3 and 4 receive most of the pump's shot.

Under normal driving conditions, all cylinders should receive the same fuel mixture. When accelerating with secondaries open, careful selection of secondary jets should ensure that all cylinders still receive a symmetrical fuel mixture distribution.

Ensuring that each cylinder receives the same fuel mixture as all of the others maximizes both power and fuel economy. Otherwise the fuel mixture for the entire engine must be made richer so that the leanest cylinder still runs acceptably well.

After running the six anowmobile carbs sucessfully last year i made a cam change to a race grind. The snowmobile carbs do not seem to be able to handle the exra demands and so after a month of fooling with pumps regs and bypasses I whippped out an old Offy I had and an ancient AFB. I made an adapter to turn the carb 90 since i had run a offy before and always hated the way they worked with a fourbarrel mounted that way. Now I am reading these posts and discovering I am not alone.
Tomorrow i will check the old carb out them mount it and try it. I got the snowmobile carbs to work but it was always a lot of work keeping everything working. Now I am just hoping for some fun turnkey racing with the old afb.
Don

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Don

I now have the carb working perfectly. The sideways turn is a huge improvement for the offfy manifold. I am doing the trans now as it was a used unit but i want to really stand on it next drag nigt and seewhat this lil six can do.
I would post a photo of the setup but I dont know how to do that for this website. there s one now at the very bottom of my Senior dragser webpage so if someone knows how go for it.
http://seniordragster.bravehost.com/mycar.html

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Don