Decking 440 block----How far can you safely go?

[Chatt69chgr]

How many thousandths can you take off the deck of a 440 block in the quest to achieve a zero deck short block?  I'am looking at having to take between 15 and 25 thousandths off right now depending on what rods and pistons I end up using (assuming my block is factory 10.725 deck height).  IF I have to and can safely go 25 thousandths what problems will this cause.  Intake manifold fitment issues?  Pushrod length issues?

[superduperbee]

Personally, I only remove as much as it takes to square up the block. You can achieve zero deck height with the piston compression height, as you probably have to have a set of pistons made anyway. The amount you are talking about removing, you will need to mill the intake, check valvetrain geometry  and use adjustable pushrods.

[firefighter3931]

No Problem removing .025 to square up the block....most factory blocks were over spec....mine was and it needed .020 to get to zero deck. The stock head gaskets are .020 steel shim and most people use a .040 composite head gasket during their rebuild so decking the block .020-.025 puts you back to stock if not very close to it. Unless the heads are milled excessively there should be no intake manifold or valvetrain geometry issues to worry about. 


Ron

[Chatt69chgr]

Thanks for that reply.  I am using the 440 Source Stealth Heads (84cc) and don't plan on milling them.  The gasket will be the ROL gasket 440 source sells which is about 40 thousandths.  I was hoping you could deck the block up to 25 thousandths without having to have special pistons made ($$).  I'am looking at between 10 and 10.5 to 1 CR and want 40 thousandths quench distance and thats why I need to have a zero deck shortblock.  I found two pistons that looks like they will work----both are forged as I don't want cast or hyper.  They are the KB822 with a Compression Height of 2.067 which has a floating pin (not sure yet if you can get pressed pin) and the Ross 82008 (floating or pressed) which has a Compression Height of 2.065.  With a 440 deck height of 10.725, a stroke of 3.75, and rod length of either 6.768 or 6.760 you can see that you are going to have a piston sitting between 15 thousandts to 25 thousandths in the hole.  And thats why I asked this question.  I figured that a lot of other folks had run into this along the way as I hear of lots of folks building zero deck engines now. 

Note that valve reliefs in the KB822 are 4.77cc total and in the Ross 82008 are 4cc total.  I used the static compression ratio calculator that KB Silvolite (United Machine):

http://kb-silvolite.com/calc.php?action=comp

has to do my calculations on CR.  They also have one for calculating compression height knowing stroke, rod length, and deck height but you don't really need it since all you do is take half the stroke, add it to the rod length and then subtract from the deck height.
I end up with 10.298 CR for the KB822 and 10.343 CR for the Ross 82008 assuming zero deck by machining the block as needed.