Has anyone ever plumed a Shovelhead's head oil return externally? If so, where is the drain tapped into the head, and where does it drain to? What size line is needed? Thanks for the info.
Bugman
My '81 80ci shov has em stock.... but they dont drain from the rockers, they drain from the base of the cylinders. so i guess you could call it half external, hah
1/8" NPT at the base of the cylinders ( front on the front cyl., back on the back cylinder ) and the drains go into the lifter blocks which have about a 1/4" barbed fitting on them.
I can snap some pics if you'd like
- Jon
1/8" NPT at the base of the cylinders ( front on the front cyl., back on the back cylinder ) and the drains go into the lifter blocks which have about a 1/4" barbed fitting on them.
I can snap some pics if you'd like
- Jon
Stock cylinders have oil line passge down the left cylinder.
You drill the heads to intercept that oil passage.
The lines can drain back through the cylinder base or into the left side of the case or back around to the oil port just beside the oil pump on the right case or even down to the timing hole to get it back down to the crankcase. You can use transmission bundy tube, 3/16".
Personally it can make your engine look a little too busy.
I too can post some pics if you wish.
You drill the heads to intercept that oil passage.
The lines can drain back through the cylinder base or into the left side of the case or back around to the oil port just beside the oil pump on the right case or even down to the timing hole to get it back down to the crankcase. You can use transmission bundy tube, 3/16".
Personally it can make your engine look a little too busy.
I too can post some pics if you wish.
if you copy the picture onto your computer and zoom in you can see what im talking about on the lifter blocks. I think your looking for something more like the feed line? (for looks) but you could always get some lifter blocks with the oil return and use those to get the oil back into the cases
![Image]()
Do you have increased oil flow to the top end that makes you think you need external lines or is this for looks?
Actually neither. When I pulled the top end last spring, I discovered that my rear head and cylinder were effed up and poorly repaired at the oil drain hole, causeing head gasket problems(constantly sucking oil into the cylinder). If I can run the oil drain externally, it eliminates that problem.
i think this is more like what you are talking about.
![Image]()
its normally done when the bore size is increased. when you bore the heads out to fit a 3 5/8 cylinder it leaves a very small amount of gasket surface between the drain back hole in the head and the fire ring.
we weld the hole up and re machine the head gasket surface. usually we just run them right back into the left case near the main bearings. some times we run them back to the primary oil return which actually sucks on the heads. it realy cuts back on blowing head/base gaskets on the bigger motors.
its normally done when the bore size is increased. when you bore the heads out to fit a 3 5/8 cylinder it leaves a very small amount of gasket surface between the drain back hole in the head and the fire ring.
we weld the hole up and re machine the head gasket surface. usually we just run them right back into the left case near the main bearings. some times we run them back to the primary oil return which actually sucks on the heads. it realy cuts back on blowing head/base gaskets on the bigger motors.
I had the same question. I got a pair of S&S 3 5/8" shovel heads with the external oil drain setup already. Below is my question thread with some good insight.
http://www.jockeyjournal.com/forum/showthread.php?t=43025
http://www.jockeyjournal.com/forum/showthread.php?t=43025
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