Deck height

[mod38-1]

I have a 360 block that was 0 decked for ross flat top pistons with stock stroke crank. I was thinking of purchasing a 408 kit with kb forged pistons. Do you think there will be any issues since block has been decked already?

 

[fishy68]

Do you know the part number for the Ross pistons? If so look them up and see what compression height they are and compare that to the KB's your looking at. That'll tell you where the KB's will land.

 

[mod38-1]

Ross piston part number 99627 comp distance 1.669. KB piston part number kb745 comp distance 1.465

 

[fishy68]

Your deck height figures out to be 9.582" if they did it right on the money so the KB's should stick out of the hole .006". You should be fine if you run a .040" or thicker head gasket. Only thing you might want to watch is the compression ratio. It can get pretty crazy high real fast with a 4" stroke and the pistons sticking out of the hole. Especially if the heads are closed chambers and/or the pistons are flat tops.

 

[mod38-1]

kb pistons are dished and heads are open chamber casting number 3769974. I cc them myself and come up with 68 being smallest and most are 72cc. kb pistons have a head volume of 20.5 cc

 

[fishy68]

You should be fine then.

 

[moper]

If you are going from a forged piston to a hyper you may have too much piston to wall clearance for them. It shouldnt hurt anything but you will see long term ring seal issues and maybe a little noise. Measure the bores carefully for taper before you order the pistons.

 

[mod38-1]

Kb pistons are forged. Thanks for the help