The arrow points to the oil drain back (return) tube. I see your engine is a 235 or 261 so the head bolt next to that tube should be hollow for the oil to feed up to the rocker stand and then up into the hollow rocker shaft and finally to the rocker arms. Oil that can't make it into the rocker shaft drains back through that tube.
Hollow bolt? Hello Evan, which of the bolts should be hollow? The bolt right unter the tube? Wolfgang
Wolfgang - I have a 235 that looks just like that, and I'm sure the copper line you've arrowed in the photo is the oil supply. If you take the rocker assembly apart, you'll see it's connected to the shaft in that other short piece of copper pipe. Oil comes up the arrowed line, along the rocker shaft and out through the small holes in the tops of the rockers. If you take the pushrod cover off you'll see the copper line continues down (behind the pushrods) into the bottom of the engine. I don't have any head bolts which are hollow. The bolts along the rocker shaft, like the ones in the photo simply hold the shaft in place and none of those are hollow either.
Pushrod cover hello Mel, I think I'll will take off the pushrod cover, make some photos and we will see. I hope I'll can do this tommorrow. Wolfgang
Open side cover Hello, I opened the side cover and find this: http://s66.photobucket.com/albums/h242/wokri/?action=view¤t=Bild004-1.jpg I took the boring machine spin the oil pump and oil came out of the hole at the rear side. I think there is missing a tube from that hole to the plug in the middle of the photo. I think this will let the oil flow to the copper tube in the cylinder head to the rocker shaft? Right? If this will be correct, someone have an idea where I could get those tube? Wolfgang
You're right, the oil comes up through that hole at the rear and into the head just as you say. I don't have any good photos of my installation to hand, this is the best I can do right now. As I remember it's just a copper pipe, bent around the pushrods, between those two points. Maybe someone makes these, but I think you'd do better to make one up yourself rather than hunt around trying to find one. Check what size fittings will go into the block and head, from what I can see of your photo it looks like you have the fitting at the bottom end, and get the pipe to match.
Mel is absolutely right and I am wrong, sometimes the fog on the old noggin gets confused with what we used to do to correct a situation to the way the factory did it. The hollow bolt or grinding a flat along one side of the bolt INCREASES the oil flow, it is not the original passage.
Top End Oiling O.K. , you have a late 235 with full pressure , this doesn't mean it's like a modern engine though . that little tube passes most of the oil up top but there's one cylinder head bolt that's wasp waisted and this helps direct more oil up to the rocker shafts ~ you needn't take it all aprt if it passes this test : engine running , remove the oil cap and increase the RPM's to 1,500 (or so) and look at the rockers , wait a bit and oil should (must in fact) begin dribbling out of the hole . it won't show oil here @ idle in most cases so don't panic . If it does dribble after a minute or three of higher RPM's , you're good to go as this is a high volume , low pressure typ oiling system , tha gauge is normally barely off the peg @ hot idle and only goes up past 15 # @ 3,000 RPM's if the engine is is tight and has new(ish) cam bearings as that's where 90 % of the oil pressure gets lost ~ loose cam bearings . using synthetic oils will clean out the accumulated crud in the tiny oil passages and increase top end oiling volume at all RPM's . It is recommended by GM to add an external oil line from the gauge fitting on the left side of the cylinder block , back around the engine and up to the 1/4" NPT fitting in the right middle of the cylinder head if you want more oil to the rockershaft . They even made kits for this , use steel tubing . Be aware that you can have too much oil in the top end and it'll get sucked past the valve guides and create smoke upon initial startup and anytime you let off the accellerator pedal , little white puffs of smoke might ensue . I hope this helps , if you want to know which bolt has the wasp waist , buy a 1958 shop manual .
