s**t I was meant to say 1 inch not 2 inch (fat finger sindrome) I'm inns test it out with plastersene on the weekend I rather 1" to definately clear aftermarket rocker covers also people be carefull when your tightening your upper manifold I crack my 1/2 spacer I was using a tourqe wrench to the correct setting too

Are we talking about the proform slant edge ford racing rocker covers? I'm running a set on the Fordrunner. A 3/8" spacer is a very close fit (vacuum tee and acellerator bracket resting on the rocker covers). A 1" would be ideal. Didn't know they made them in 2".

On a side note it would be interesting to see if you can tap a set of vapour phase lpg injectors into the spacer instead of the manifold.