The V8 Owners Forum -

Hi,

First post on this forum.

Can you answer the following? (also, why don't my posted images show up)



Twin SU Manifold machined



As I now have the Holley I have to find out as to what I must next do to the manifold .

I have attached photo and sketch of manifold and possible machining options. I would be more than grateful for any info you may be able to give me.

As you can see from photo I have cut off original carb mounting block and machined down to manifold flat.

On the sketches Fig 1-2 show how fuel is distributed thro manifold to cylinders before machining. A double plane manifold.

Fig 3 shows if I machine straight thro to expose all, and bolt carb on top Fig 4 shows if I do same but weld plate in middle which would be best and more important which would work.
Am I on the right track or way off ?

I appreciate I may have to weld a block on top of manifold to mount carb.

edited by Coops

I would advise against figure 4, as the firing of cylinders 2,4,6,8 is not evenly spaced in time, so you won't get a uniform flow-rate through that half of the carb. It will only work properly if you get a flat-plane crankshaft.

With fig. 3, you get a plenum effect underneath the carb to balance the flows.

If you kept the original SU dual-plane configuration with one 'port' serving 1,4,6,7 and the other 2,3,5,8, your Holley would still see a uniform flow on each half.

Chris.

Hi
As Chris says best if you avoid having one side of the engine feeding off the same two of barrels of the carb, either have it as an open plenum manifold or buils up a spacer so you can keep the existing dual plane set up.
Best regards
Mike

hi m,ate,
the reason why no pics are shown is the link to them must be wrong,

Hi

I keep trying but no luck. Is there a size limit on images? You can post my link to your browser and go straight to it so the image does work, it must be something silly i am doing.

Just seeing if I can do it:







Wierd.....

Chris.

Twin SU Manifold machined



It's all that ? and number gubbins on the end

I know it's an old post, just wondered if there was an end to this as I am about to do the same.

Jon