Rick-
Thanks for asking all the questions you've been asking- believe it or not, these are the exact questions that I have been wondering about myself.
As for this question, I was at ERA last week and took a look at how they ran the
oil pressure line on a turn key car they were finishing and they routed it as follows:
Starting from the back of the gauge, the line went all the way to the left hand side (driver's side) of the firewall. From there, it went through the firewall and seemed to run underneath the bottom inner lip of the fender/hood opening until it was next to the filter. Once it reached as far forward as the filter, the line went straight down along the inner fender well and then connected to the pressure fitting on the filter adaptor.
Bob, did I do it right?
