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Thread: Olds oil....again...sorry!

  1. #1
    Ok, I know this is an old subject, and ya'll are tired of talking about it, but, be patient with me, I am new to this whole jet boat thing, and Olds to boot.
    IN my olds 455, I am thinking of running drain lines from the heads to the pan. Good? Bad? should I do it at all 4 corners? what size plumbing would work best? Sorry again guys, I read the forums, but seems like mixed opinions. dont get pissed, just try and help me. Thanks!
    I am not made of money, so all the high tech, machine shop stuff wont fit in the budget right now!

  2. #2
    2 Lines... one each from the back of the heads to either the lifter valley, or all the way to the oil pan. I think most people recomend -6 (3/8" lines) hose.
    The restriction is the oil drain back hole in the head... it's teeny-tiny. Once the oil gets out of the heads, it quickly returns to the pan, so there isn't really a need to go all the way back to the pan with the lines.

  3. #3
    From the Olds FAQ page....
    Oil Return from Heads
    The oil goes up top. Here is how to get it back down to the pan faster. Complaining about leaking valve covers? This modification solves that, and more importantly, helps oil return to the oil pump. Here goes:
    I did this project when I had my mill (just torn down and still dirty) on the stand, so that is the only way I'm going to recommend doing it. Full credit for the idea of an external oil return system goes to Joe Mondello, who told me he does this to race and marine (i.e. heavily flogged) engines. By the way, the purpose of this whole thing is better oil return. The leak free valve covers are a nice bonus.
    First thing to do is get your die grinder out and enlarge the oil return hole (downward) that is located at the front of the lifter valley. Blend the lower side of the hole downward so that any oil coming down from the front oil return holes does not pool in the valley, but instead will drain immediately down through that round hole.
    Next, use your die grinder to smooth out the entrance to the oil return holes located at either end of the cylinder heads. This is especially important for the rear (towards the firewall) holes, since the natural tilt of the installed engine pools the oil to the back of the head. Typically, these holes were simply drilled into the head perpendicular the head surface, so there is alot of improvement that can be made to the entrance of the hole. The end result should look like a funnel. BE VERY CAREFUL ABOUT GRINDING TOO MUCH!!! You want to make a funnel, not a canyon. Just use a fairly fine burr in your grinder so that a nice satin finish results.
    Closely examine your oil return holes and you'll see that the large gallery drilled in from the valve spring area is intersected by a small gallery that actually returns the oil to the valley. For the motor head with a good collection of burrs, a long shaft burr with a small (¼") head can be used to do some limited smoothing out of the intersection of the galleries. By looking down the large gallery, you can see that the oil must climb uphill to reach the entrance to the small gallery. Since oil can't climb, it pools in the valve spring area until it reaches a high enough level to spill down the small gallery. With my engine on the stand and the valve covers/intake manifold off, I poured oil over the valve springs to simulate the oil return process in a running engine. I had oil all over the floor and none coming out the return hole into the valley. That explains why my valve covers would frequently leak. They were literally holding about 3 ounces of oil each due to the poor oil return design of the Olds cylinder head. Six ounces doesn't sound like much, but I want every ounce in the oil pan, not in the valve cover area.
    Make sure you have each head on the correct side of the engine (I think they're interchangeable too, but I've always kept them on the same sides; don't ask me why...) You will be installing 90 degree elbows on the back of each head. I did this four years ago, and as I recall, I used ¼ NPT fittings. Once you read this, you can decide on the size of the plumbing for yourself. I drilled a hole into the back of the cylinder head to intersect the large gallery that comes down from the valve spring area. Use a depth gauge or similar tool to determine the correct spot to drill. There is a bulge in the casting that corresponds to the gallery, so this is pretty easy to do. Ideally, the bottom portion your drilled hole will intersect the large gallery at its bottom. In this way, you will get maximum drainage without drilling into unknown territory. Tap the hole for the appropriate thread size. Repeat this operation on the other head.
    Next, you'll have to decide where to drill the back of the block to install a tee fitting. Joe Mondello recommended using the machined portion on the vertical part of the block(right below the area where the rear intake mani seal would go) near the distributor hole. The important thing here is to place the hole lower than the holes you drilled in the heads, so that gravity can do its thing. You won't have a whole lot of difference in height between the block holes and the head holes, since the block hole will have to be drilled high enough to allow you to screw in the tee fitting (that's an important thing to check BEFORE you drill!!!). As I recall, my block hole is about ¾" lower than the head holes. Before you drill, make sure the distributor clearance is accounted for.
    Now, you simply connect the heads and the block using your choice of braided steel line or fuel line. Joe uses braided aircraft hose. I used metal fuel line because I had just spent most of my available pennies on a RAM clutch and pressure plate. I should not have used metal line because 1) the bending and precise lengths required really taxed my patience and 2) when I was smugly enjoying the rather nice finished result, it dawned on me that I could no longer remove my distributor! Once the engine is reinstalled, space is very tight, and there is no way you're going to get in there and disconnect metal lines. I could rotate the distributor for timing changes, but removal was not possible. Off came the metal pipe and on went ½" heater hose with double clamps. Make sure you keep the set up flowing downhill from heads to block, but tight enough to allow easy engine installation. Since the oil return is not under pressure, braided line is total overkill. But guess what I'll be switching to next time the motor is out for PM? Yep, Mr. Mondello's advice to me has never been wrong. I'll be installing braided line.
    This has been a long posting, but it's worth it. Once you have the engine on the stand, this will be much easier to conceptualize. When I repeated my oil pouring experiment, no oil went through the stock rear return holes in the head. Every bit went through my newly installed return system. Complimented by some contouring with the die grinder to the rear of the valley beneath my newly drilled hole, the oil now returns down the back of the valley, directly above the sump. The important thing about this project is to carefully visualize and do lots of "mock-ups" before you drill anything. Also, clean everything thoroughly when you are done (meaning garden hose clean). Now my valve covers never leak, so I've been able to switch to the extra-thick Mr. Gasket cork gaskets, which gives me clearance for Mondello's SAR-455 adjustable roller tip rockers under stock valve covers. One more thing, this set up is virtually invisible when installed, so even stock purists can take advantage of a race proven oil return system. I've had my hood opened up for some pretty sharp Olds fans, and nobody has ever spotted it. However, it is difficult to service any leaks, so do it right the first time or get your hoist ready.
    Next time I have the engine out, I may reroute these lines down the side of the block and then directly into the oil pan. Should be fairly easy and more accessible in case of leaks.

  4. #4
    2 Lines... one each from the back of the heads to either the lifter valley, or all the way to the oil pan. I think most people recomend -6 (3/8" lines) hose.
    The restriction is the oil drain back hole in the head... it's teeny-tiny. Once the oil gets out of the heads, it quickly returns to the pan, so there isn't really a need to go all the way back to the pan with the lines.
    thanks Sleek Jet. does anyone have pics of how it should look?

  5. #5
    Good info. I used 3/8 npt fittings and -8 lines. Also, i would not use 90* adapter fittings. I try to avoid them whenever possible. Instead, used 90* hose ends which have a smoother bend to improve fluid flow. Just my opinion.

  6. #6
    click on "455 guy's..engine buildup"
    he shows atleast pictures of where the holes go.
    or goto "" click on "tech articles" then i get lost.i believe it's the 4 or 5th article--455 build by mondello-- or its another article(cant remember) but he shows some pictures too!!

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