[wilf leek]

Gerry - I would have thought that was a pretty extreme cam grind to exhibit that effect, could you post the specs for us ? Matching the power valve to the engine vacuum characteristics is a step well worth doing. It would be a simple matter to temporarily hook up a vac guage and run the pipe back to the cockpit to see exactly what is happening at different throttle openings.

Be careful though - when I did that I was concentrating so much on the guage I nearly drove off the road!

Now you have to get your builder to explain the excessive blow-by.

Luck.