Inliners International Forums General Discussion Engines GMC rocker shaft oiling

I was reading the new 12 port news tech question about low oil pressure in a 261. Pat suggested pinching off or blocking completely the rocker overflow tube to stop the bleed off of oil.This seems like a great idea I can apply to my 302. I'd like to block the overflow off completely. Has anyone had issues with this?

I blocked it on my 235. Makes better pressure and stoped the oil mess from the valve and side covers. Should work the same on a 302.

In 1958 GM changed a part of the oil flow in the 235 and they also blocked (pinched the tube) the overflow also in the factory.

I cut the tube and used a bolt and some locktite.

On a GMC,the oil line goes into a fitting screwed into the front of the head.That fitting has a restriction of about .060. Later 235/261's also had a restricted oil flow to the head.
Blocking off the oil overflow pipe is OK,but don't expect any increase in hot oil pressure at road speeds if the restriction is in place.

Thanks for the info. I closed the restriction to .040 on my 302 just after it was rebuit. I thought there was just too much oil comming out the bypass tube. My road speed oil pressure is fine, it is the idle speed pressure I'd like to increase.