My 1st attempt at a tubular manifold

[Richard.]

You'll find a purge on the inside not only protects from internal coking but it actually helps with the quality on the face side too. It's well worth setting one up and easy too. A Y peace and two flow meters is all that is required.

 

[Turbo]

That's quite good, especially for a first attempt. As others have said, you should purge it - Stronger welds & a nice smooth finish inside to help gas flow.

I would also advise bolting the manifolds to an old head or some thick steel plate. You may think the manifold is strong enough but it is amazing how it ends up bent with those large pipes pulling on it. I learned that lesson the hard way on a 4-branch manifold I was repairing - it ended up so bent I couldn't use it.

My fear about manufacturing stuff like that would be 'painting myself into a corner' ie ending up with a weld in a location that can't be welded!

 

[Paulbarrett]

I got royally stuck with 2 welds on the collector, but lesson learned, cut it up and welded it prior to adding to the manifold

 

[Brad93]

With collectors a lot of people like to use the super large diameter gas lenses with a spiece of scotchbrite inside so they can use an inch and a half of stickout. Alot of shops geting billet collectors made now too.