The Stovebolt Site Forums The Shop Area Engine Shop Oil lines.

Hello again. I am now putting my 270 GMC together and I have come up a another problem with the oil system. The factory oil lines have a type of taper furrule on a small steel line. A thread all there own. It goes from the lower part of the block from a brass fitting the screws directly into the block. One goes up to the head for oiling the rockers. It is a small line and is all steel. That one is good. The others are rubber and go to the oil filter. I want to replace the oil lines to the filter housing. Trouble is I can not find anybody to duplicate this type of line. I have been to hydraulic specialist to regular parts house. I could covert them all to pipe if it weren’t for the smaller steel line to head with the special fitting to the head. All this clear as mud😀😀. Anyway does anyone know is there is an after market supplier that make GMC oil lines? Chevys are different and pipe thread will not work. Thanks. Davie.

I would fabricate my own lines out of copper/nickel brake tubing, 3/8", you could make regular flare, inverted flare, or compression connections and use all fittings that are readily available at hardware or automotive stores.

Not sure about theGMC, but on the 235, they are inverted flare and NPT. If you make your own lines, you need to make sure that there is a 1/16 orifice either in the line, or built into the filter. If not, you will lose oil pressure in the engine. All the oil will try to go through the filter.

You are right about the small orifice. Chevy lines have that built in them and on the small steel line up to the head on my 270 has an even smaller one. Thanks Stan

What oil canister do you have the L-1 or S-2. The S-2 line is still available P/N 2137793.

Gmc used an Orifice Nipple (6107443) at the head and the line was just a 3/16 fitting and copper tubing.
The thread on your small line at the head could be UNC or UNF. A picture would help.

Yes that is exactly what I have in the head. The bigger line to the oil filter from the block is my problem. Sorry I do not know what oil filter canister I have. How do I tell the difference? Thanks Dave

The gray one is the L-1 canister 1 quart, about 6 ½’’ long and 5-inch diameter. With the bracket welded on.

The S-2 is 2 quarts and 11 5/8” long, 5-inch diameter with a separate bracket.

I have the L-1 filter housing. Thank you it’s goo to know. Dave