Torque value for M8 compressor head bolts

[uninformed]

Hey all,

I have to replace the head gasket on my small 240v air compressor. The bolts are M8 socket caps. Im guessing the cylinder is cast iron, the head is alloy (bolts pass through). So M8 into cast iron....what torque value would I be doing up to?

[bee utey]

Google it:

https://docs.google.com/viewer?pid=bl&srcid=ADGEESgszewudJFUAgK7ZuApb88EwpwAxZ90qotYE6BW TUHO_IBaftpNNABAsXccV7dSKGS7A6OTwGStYtpxs66262OU2-NprRNklLu3hr53rvUl3o23usaDlUr730CDDkrRUdckWWwn&q=cache%3AvaLBGpq12KwJ%3Awww.npfasteners.com%2Fpdf s%2Fmax-rec-tightening-torque.pdf%20&docid=8f20dca3e6d6c23338d49d75f8cd6d2b&a=bi&pagenumber=1&w=800

[Blknight.aus]

20-40nm depending on bolt grade. (manufacturer, head size and thread pitch all come into it)

8.8 is 20nm and 12.9 is 40nm. for fine pitch threads -~5% for coarse.