Hi

I do believe this is my first post, so Hi again!

I've a 1950 GMC PU with a 228 motor, and I've the head off at the mo, would it be a good idea to reroute the filtered oil to the head instead of back to the pan, or would that starve the bottom end?

Cheers

Hi Shox Dr . . .

Welcome to the forum. I am not sure that I am following the 'plumbing' change that you have in mind. The fitting on the front of the 228 is taking pressure from the main oil gallery in a peripheral fashion sometimes called by-pass pressure. The factory fitted a T connection sending part of this output up to the rocker arms through a fitting in the head. The other side of the T went into the oil filter.

Are you thinking of eliminating the T and sending all of the output from the gallery into the filter and then sending the output of the filter up to the rockers?

Please elaborate.

regards,
stock49

Yes, sort of leaving the Street Tee in place, for the gauge in the cab.

Blanking off the feed to the head, and using the outlet from the filter to feed the head I was also thinking about a gauge in the feed from the filter to the head, just to make sure the filter wasn't restricting flow.

I'm not familiar with the GMC engines, but I have seen it done on 235's. It actually makes alot of sense to feed your rocker arms vs. just dumping it back in the pan.

In the case of the 235, you would need to block off the internal oil feed, otherwise you would be getting too much oil to the top end.

You still may even get too much to the top end, so you may have to put an orifice inline to help control the amount of oil flow.

I had wondered whether redirecting it all to the head would flood the cam cover, so have thought of using the gauge I intend fitting on the head with a bypass to adjust the flow, re-redirecting any excess back to the block. Reusing the original tapping.

That sounds like a good plan. As I understand it the rocker arm line does restrict flow (by the size of the opening in the fitting). The only other caveat is that the factory design allows for filter neglect. Should it become completely clogged the rocker arm line would still flow through the other side of the T. With your design the filter must be looked after diligently.

Agreed, it goes without saying.

Head's been refurb'd, bottom end seals replaced rockers cleaned.

The block is been left well alone at the moment, I tested compression last December. 150/5psi in all pots, so although the bores are glazed, and the pistons worn all is good, So I hope it has a good few years to live, if I look after the oil.

Sounds like a fun project and great drive. Would love to see some pictures.

That is how I have always run my 235 and 261 motors. The 55-57 235 blocks for example, you can pull the side cover and plug up the two drilled bosses for the steel line that runs from the back cam bearing to the head and run a line from the oil filter output to the plug on the side of the head that will feed the rockers directly. You have to use a line from the oil filter that is the same size as the stock output line or you will put too much oil on the rockers. The benefit is that the rockers, which are damn expensive to have rebuilt these days, get clean filtered oil, and a steady supply. Interestingly enough, back in the day the stock line behind the lifter cover frequently got clogged and the aftermarket sold kits to divert the oil filter oil to the head as above. You may be able to do the same with the 228.