It is just visible in this picture where the o ring is right at the edge of the block filter pad.

Just finding this thread. I have a pair of 502/502 crate engines that have spent their life in a boat (not mine).

I recently freshened one up that had been marinized before in the cam and valve train area but not sure in the block. Had a marine builder rebuild the short block and we did not check these by-passes. I do have higher than expected oil temp for a 525HP engine with top of the line remote filters and -10 lines. I see 200-210 at easy cruise, and 250 if I lean on it very long.

The second of the 2 is in my garage for a build. I just went out and removed both bypasses and suspect they are both still in the block I am running.

I'll be anxious to see what it looks like when I get it out this winter. Its run fine so far this summer, so it will probably get a few more hours on it as is.

Great thread showing what OSO should be!

I pretty much followed this thread as gospel when I was plumbing my oil system.

Having the bypasses in there isn't a big deal, but do you have the right bypass valves is the important question, and there's no way of telling just by looking at them. From what I understand if you have the 15# valve in there with a remote filter it's only a matter of hours before the bearings are toast so if it's lived this long you may be ok. I don't think the one under the nipple is a big deal until you start getting well above 600hp. -10 lines may still be too small and giving you higher temps. Have a look at this:
http://www.offshoreonly.com/forums/g...il-temp-7.html

Fwiw, I was able to get to my bypass valves with the motor still in the boat. It wasn't fun, but it is doable.

A great thread on oil hardware. Does anyone know if the 500 EFI oil cooling system has larger lines/cooler and would be a reasonable solution if a nice used one is located? Going on a 502 Mag with Whipplecharger.

When i rebuilt a 500 efi 2 years ago for a friend the oil lines were decent compared to the tiny holes in the gen 6 502 mag mpi 415 hp stuff. Keep in mind the problem with 502mpis and these tiny lines becomes s serious issue when guys open up rod and main clearances and install a high volume pump, THEN they become a huge restriction and block bypasses open and regulator bypass in pump is probably buzzing its ass off trying to let oil that cant flow relieve the outlet pressure thats backing up!!

Ttt. 😎

........it has 11lb bypass relief valves. If your motor has unknown origin,who knows what it could have. Buy a new 30lb bypass relief valve for the outside(the one near edge of block casting for filter adapter) or plug it off,they are available at your local chevy dealer part #25013759,they are under 5$. The middle valve directs oil to the cooler fittings...............

Where exactly are the above valves (on the engine) as described in the OP's original post?

They are on the block under the block adapter,the outside valve in the photo has been removed and pluged up

Thanks I'll have to check into the location of the block adapter. I'm guessing this is where the oil filter would be in an automotive application, bottom side?

I have low oil pressure on a OE 416 hr. '96 7.4 lx mpi. Aside from a bad dash mount oil pressure gauge I don't see why the pressure would be low. I'm hoping switching the valve would help with the pressure issue.