I saw a rebuild kit on ebay for a 400 and the pistons have a slight dish. This is for a stock rebuilds, so the pistons would be 8.4:1. I have a machine shop at work and I was wondering if I could machine the dish a little deeper to get the compression down for the Aussie heads. What I would like to know is how much depth I need to machine them down to. If I know how much depth I need to cut, then I will get this kit and cut all the pistons myself and save a little money.

 

The problem with the stock type pistons is not the dish itself but the compression height (how far down in the bore the piston sits). Even if you enlarged the dish in those pistons you still wouldn't be able to achieve the quench you need because the top of the piston won't get close enough to the head to provide the turbulence you need for quench.

 

I would talk to the piston mfgr. first.

 

I was checking out an engine kit on ebay and the kit is for a 71-'79 Ford 400. The compression ratio listed for these pistons w/ the stock heads is 7.9:1. What would be the compression of these pistons w/ Aussie heads. Thanks!

 

factory 400 cylinder heads varied from 75.6-78.4cc or so. those pistons might give you 7.9 with the larger chambers, up to 8.4 or higher with the smaller chambers, depending on how much the block/heads are shaved to clean things up. 58cc Aussie heads will raise static CR to at least 9.6, which without quench would require high-octane fuel and most likely a bigger cam to bleed off dynamic compression...

 

So I guess I will get the quench pistons from Tim Meyer. Talked to him on the phone today and he was as helpful as he could be. Have to get my block to the machine shop to see what work it needs first and then I will get the pistons from him. -Mike