Good day,

I don't have access to the OLD GMC trucks website but I am needing instruction and photos that illustrate the conversion of a GMC 302 to full pressure oiling system.

Can someone help me and if they have photos and the process written down? I will send you my email address if you can help. Thank you. --Tom in New Hampshire

Here you go, its in the Tech Tips section on the Home Page.


GMC Full Flow Tech

GMC engines are full pressure from the factory with rifle drilled cranks. The Tech Tip is for providing full filtration - diverting all oil flow through the filter. Back in the day there were no detergents in oil. This caused contaminants to fall into the pan - which could be scrapped during periodic service intervals. Those engines that had oil filters were only by-pass affairs where some oil passed through the filter via peripheral circuit. Once the filter became clogged no oil passed through the filter. When converting to full flow through the filter circuit the remote filter housing needs incorporate a bypass or you could the starve the main oil gallery.

I recently read an article saying with modern oil and fuel and regular changes filters are not really needed. Full flow filters make me feel better although even with the old systems eventually filtered all the oil just not on every pass.

I figured that's what he meant, since like you said, they're already full pressure. And Full Flow would be the only conversion needed for the GMC's.

thanks for your patience. I was looking for a tech article to convert to the full flow conversion. thanks. Tom