Decking a block
From Crankshaft Coalition Wiki
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| + | ==What is "decking" a block?== | ||
| + | Decking a block is firstly a machining operation in order to square the decks to the main bore and get even distances from the center at all corners of cylinder decks. At the same time we have to restore a proper sealing surface for the gaskets we will employ. | ||
| + | |||
| + | ==Determining and setting the quench, or "squish"== | ||
Setting the squish is a must-do if you expect optimum performance on pump gas. It is generally accepted that 0.035" to 0.045" is pretty much ideal. You can do it with a 0.025" piston deck height and 0.015" gasket or you can do it with a 0.012" piston deck height and a 0.028" gasket or you can do it with a zero deck height and a 0.039"/0.040" gasket. | Setting the squish is a must-do if you expect optimum performance on pump gas. It is generally accepted that 0.035" to 0.045" is pretty much ideal. You can do it with a 0.025" piston deck height and 0.015" gasket or you can do it with a 0.012" piston deck height and a 0.028" gasket or you can do it with a zero deck height and a 0.039"/0.040" gasket. | ||
Don't cut the decks until you have all of your reciprocating assembly parts on hand to measure. And be careful when you buy pistons for a 350. The preferred ones will have a 1.560" compression height. "Rebuilder specials" will have a 1.540" compression height, requiring additional meat to be whacked from the decks. If you are planning on using cast iron heads, then the thickness of the gasket makes little difference. If you are using aluminum heads, you must use a thicker (0.039"/0.040") composition gasket to prevent brinelling the cylinder head, so you're generally talking about zero-decking the block in this case. Fel-Pro 1003 works well on a 350 aluminum head install. | Don't cut the decks until you have all of your reciprocating assembly parts on hand to measure. And be careful when you buy pistons for a 350. The preferred ones will have a 1.560" compression height. "Rebuilder specials" will have a 1.540" compression height, requiring additional meat to be whacked from the decks. If you are planning on using cast iron heads, then the thickness of the gasket makes little difference. If you are using aluminum heads, you must use a thicker (0.039"/0.040") composition gasket to prevent brinelling the cylinder head, so you're generally talking about zero-decking the block in this case. Fel-Pro 1003 works well on a 350 aluminum head install. | ||
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If you don't know how to figure static compression ratio or which volumes are involved, just ask me. I will be glad to explain it to you. | If you don't know how to figure static compression ratio or which volumes are involved, just ask me. I will be glad to explain it to you. | ||
| − | == | + | ==Static compression ratio== |
| + | [http://www.wheelspin.net/calc/calc2.html SCR]] | ||
| + | |||
| + | ==Dynamic compression ratio== | ||
| + | *[http://www.wallaceracing.com/dynamic-cr.php Wallace Racing DCR calculator] | ||
| + | *[http://www.empirenet.com/pkelley2/DynamicCR.html Kelly DCR calculator] | ||
| + | *[http://www.uempistons.com/calc.php?action=comp2 KB/Silvolite DCR calculator] | ||
| + | *[http://www.rbracing-rsr.com/comprAdvHD.htm RSR DCR calculator] | ||
| + | {{Note1}} Some dynamic compression rtatio calculators (like KBs) ask for an additional 15 degrees of duration be added to the IVC @ 0.050" lift point figure. This works OK on older, slower ramped cam lobes, but the faster lobe profiles may need to have 25 degrees or more added to be accurate. | ||
| + | |||
| + | {{Note1}}If the intake valve closing (IVC) point isn't known, it can be calculated: | ||
| + | # Divide the intake duration by 2 | ||
| + | # Add the results to the lobe separation angle (LSA) | ||
| + | # Subtract any ground-in advance | ||
| + | # Subtract 180 | ||
| + | This result does not need to have any amount added to the IVC point, like the KB calculator calls for.*[http://www.wallaceracing.com/dynamic-cr.php Wallace Racing DCR calculator] | ||
| + | *[http://www.empirenet.com/pkelley2/DynamicCR.html Kelly DCR calculator] | ||
| + | *[http://www.uempistons.com/calc.php?action=comp2 KB/Silvolite DCR calculator] | ||
| + | *[http://www.rbracing-rsr.com/comprAdvHD.htm RSR DCR calculator] | ||
| + | {{Note1}} Some dynamic compression rtatio calculators (like KBs) ask for an additional 15 degrees of duration be added to the IVC @ 0.050" lift point figure. This works OK on older, slower ramped cam lobes, but the faster lobe profiles may need to have 25 degrees or more added to be accurate. | ||
| + | |||
| + | {{Note1}}If the intake valve closing (IVC) point isn't known, it can be calculated: | ||
| + | # Divide the intake duration by 2 | ||
| + | # Add the results to the lobe separation angle (LSA) | ||
| + | # Subtract any ground-in advance | ||
| + | # Subtract 180 | ||
| + | This result does not need to have any amount added to the IVC point, like the KB calculator calls for. | ||
| + | |||
| + | ==References== | ||
*[[Quench]] | *[[Quench]] | ||
| + | *[[Block deck height]] | ||
| + | <br><br> | ||
[[Category:Undeveloped articles]] | [[Category:Undeveloped articles]] | ||
[[Category:Engine]] | [[Category:Engine]] | ||
| + | [[Category:Undeveloped Engine articles]] | ||
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