function calcLength() {
	if(document.form1.deck1.value == "") {
		alert("Please enter case deck height in inches!")
		document.form1.deck1.focus()
		return false
	}
	if(document.form1.gasket1.value == "") {
		alert("Please enter base gasket thickness in inches!")
		document.form1.gasket1.focus()
		return false
	}
	if(document.form1.cylinder.value == "") {
		alert("Please enter cylinder length in inches!")
		document.form1.cylinder.focus()
		return false
	}
	if(document.form1.gasket2.value == "") {
		alert("Please enter head gasket thickness in inches!")
		document.form1.gasket2.focus()
		return false
	}
	if(document.form1.deck2.value == "") {
		alert("Please enter head deck in inches. 0.00 if not milled!")
		document.form1.deck2.focus()
		return false
	}
	if(document.form1.portdiam.value == "") {
		alert("Please enter inlet port diameter in inches (round ports)")
		document.form1.tportdiam.focus()
		return false
	}
	if(document.form1.headtype.value == "") {
		alert("Please enter 0 for S&S Supersport and Stock Heads; Enter -.515 for S&S SA/B1 Heads; Enter -.480 for S&S SA/B2 Heads")
		document.form1.headtype.focus()
		return false
	}
	
	temp1 = (document.form1.deck1.value * 1)
	temp2 = (document.form1.gasket1.value * 1)
	temp3 = (document.form1.cylinder.value * 1) + (document.form1.headtype.value * 1)
	temp4 = (document.form1.gasket2.value * 1)
	temp5 = (document.form1.deck2.value * 1)
	tempin = (document.form1.portdiam.value * 1)
	temp7 = ((temp1*1)+(temp2*1)+(temp3*1)+(temp4*1))-(temp5*1)
	temp8 = ((((((temp7*1) * .3826834324) - 4.2083607055) + 2.050)) * 2) + .02
	temp9 = Math.round(temp8 * 100)
	temp10 = temp9 * 1 
	result1 = (parseInt(temp9 * 100) / 100) 
	result4 = tempin * .5
	result5 = result4 * 1.0746
	result7 = Math.round(result5 * 100)
	result6 = (result1*1) - (result7*1)
	result3 = parseInt(result6 * 100) / 100; 
	document.form1.length.value = result1; 
	
}