Ruler? Funny. (not)
I used a Mitutoyo Digital micrometer, accurate out to .01 mm, +-.005 mm.
The reason for the variation was because the diameter for the runners was not the same in both the x and y axes. Therefore if they were more eliptical then I put down the full range. The SVT upper manifold can be expected to be eliptical because of how the Xtrude honing forces putty through the tube. You will get preferential wear at the outside of the turns in the tubes.
For the 3L manifold, the rough surface of the tubes results from casting flash and gives rise to a larger amount of error. As far as the lower manifolds, they are initially bored out straight through machining (not left as-cast), and the xtrude hone on the SVT lower is not very agressive, so they are both very similar in diameter and the SVT lower doesn't exhibit any eliptical shape as there are no turns in the lower manifold.
I was very careful about all the measurements, and I even made them more than once due to a request from Bradness.
Which ones were larger than you expected, the SVT manifold, or the 3L manifolds? If you mean the 3L stuff, then I still have it available and I can re-measure it. Unfortunately I cannot re-measure my SVT manifolds as the SVT manifolds are now much larger from being widened, and I can only go by the notes that I took.
I was very carefull with my measurements, but let me know if I can be of any more assistance.
warmonger
