The V8 Owners Forum -

I've just fitted a new set of pistons to the 4.6. These ones dont have the valve cutouts. I've fitted one head back on with all the rods etc back in the right positions. I've fitted some test springs to the valves as well. With each piston at TDC on that bank, I get (as best as I can measure with the vernier) 2mm of movement if I push the inlet valve down by hand until it hits the piston. This is the amount of play with the lifter fully extended so none of this movement is pre load. My understanding is a safe min clearance of 60 thou. I seem to have 79thou.

Is this going to be enough to allow for expansion etc?

Thanks
Perry

Clearance at TDC is irrelevant as your valves are closed then anyway. You have to make a dummy lifter and check clearance on rotation with a dial guage. www.v8scimitar.co.uk/technical/803.pdf have a read.

Pay particular attention to the exhaust valve as it's opening at the same time as the piston is rising.