Posted by Chris Case [162.158.255.119] on Sunday, April 03, 2016 at 08:35:07 :
In Reply to: zink additive.. oil posted by junkyardog [108.162.219.180] on Sunday, April 03, 2016 at 08:25:44 :
Flat head valve springs only have 35# spring, and direct pressure. A more modern engine might have 70# springs and a rocker ratio of 1.7, so 120# on the lobe.
Unless the pan and crankcase have been cleaned out, go non-detergent. 30wt will probelby be the only choice.