> Does anyone know where I might find a manifold or adaptor to mount a single
> Weber on an R 1600 in a 1968 SPL311?
If you're talking about a single sidedraft, DCOE series, while you might
find an intake designed for the R-16, I doubt you'd ever be happy with it. I
spent over a year trying to tune a single Weber 42 DCOE on a Warneford(?)
manifold on an L-16, and while I got it to run, it never ran well.
The problem is the most, if not all, single sidedraft manifolds for inline 4
cylinder engines are designed. The intake runners to the two middle
cylinders are much shorter and straighter than those going to the two end
cylinders so the middle cylinders run far richer than the end two, no matter
what you do.
If you could find or build a manifold that feeds cylinders 1 and 3 off of
one throat, 2 and 4 off of the other and has equal length runners to all 4
cylinders it might work. Pierce Manifolds might be worth contacting for
advice and info.