Oil Drain

[Ronnie Russell]

Now that the W-heads are all running cool, I thought a new subject might be interesting. Please take a W-head and place on a block, or set a head on a bench at approximately the correct block angle. Notice the two oil drain holes ( one at each end). Notice the relationship on the drain hole and the dump hole that exits into lifter valley. Optical illusion? Does the oil drain up-hill? Comments??? Explainations???

 

[johnnyrod]

I was looking at the same thing when I had my heads off just recently and I thought it was a bit of a weird angle and I didnt think the oil return was all that fast or not untill there was a ton of oil up there. Are we going to redesign the heads now? Sounds like fun. Serious now they are odd. Maybe its so that the oil runs back slower onto the lifter gallery for better oiling who knows. John

 

[dunhamfield]

I noticed the placement of the drain holes and am glad that they are the way they are.
The machine shop that rebuilt my 333 heads installed large positive valve stem seals. After running the engine a few hours I pulled the valve covers and found lots of peices of these seals laying on the head.
Thank GOD that they would not flow uphill to get into the engine.
I removed the seals and installed the quadring seals that came in the rebuild gasket kit.

 

[60biscayne]

Oil Drain Holes

Yes, you are absolutely right. I was assembling my 409 on the engine stand last week, and I also noticed the relatively small oil return holes. Only one on each side, plus there is a 90 degree turn where the hole changes directions, uphill! The engine was almost level side to side on the stand. The holes sure looked to me to be going uphill before they dumped into the valley area. So, I took my old oil squirt can(with good oil in it), and it suirts quite a bit with one pump. I shot 8 pumps in the hole, from the head side, and it still didn't come out of the hole. With a penlight, you could see the level rising in the hole from the valley side. These are fresh, clean heads, too, by the way. Straight from the shop. So, in other words, a little pool of oil has to form on the head side of the oil, before it even thinks about coming out of the valley side. That really surprises me. In fact when I was Pre-oiling the engine, with the valve covers off, the oil pooled up enough, to the point that it started leaking out of the head, and down the side of the block, before the drain hole started draining. So, with your valve covers on, and the engine running, there must be quite a bit of oil sitting in the heads at any given time. I'm surprised I've never seen this mentioned before now on this forum. Maybe, it's just not a problem, as long as you keep your oil clean, and full. Coincidentally enough, a friend of a friend of mine, has a 59', with a 348 in it, the thing always smoked, he pulled it to get it rebuilt, and ALAS, his oil drain holes were plugged!! I would have to say they appear to be VERY sucseptible to this, if you don't keep the oil religiously changed. Oil and sediment don't run uphill too well. Any other thoughts????

 

[jim_ss409]

I remember thinking that a guy could probably just drill the drain holes out bigger, but when I looked at them (690 heads) I saw that there isn't a lot of metal there.

 

[SS425HP]

Oil drain back

I remember at the convention, Lamar was talking about the drain back on the 409 being so bad. I didn't go to the seminar, but was told he talked about this quite a bit. One reason not to use a BBC high volume pump. It would pump the pan dry because the oil was up top and not draining back fast enough. Maybe the new aluminum heads can be made to address this. Whenever they become available.

 

[SS425HP]

Jack Gibbs

I see Jack Gibbs is on here. He was at the convention. He builds 409s. What is your exprience with the drain back, Jack??????????????

 

[oldskydog]

I wonder how much air pressure builds up under the valve covers with the engine running. I would think that with all that valve train motion maybe there is enough pressure to help push the oil on through those drain holes.

 

[Ronnie Russell]

Cecil, Thanks for the input. I thought maybe one of our engineer buddies might explain. It really does not matter, the system works, always has. I just found it funny that it appears the oil drains uphill. We spend a lot of time trying to relieve pressure in the engine, so I dont know if there would be enough to push the oil through the drain passage. I thought maybe that the drain hole valley filling with oil might use atmospheric pressure to push it up. I just dont know. Just guessing .

 

[models916]

Exhaust valve springs

i would have thought it is to keep the exhaust valve spring cooler in puddle of oil.

 

[oldskydog]

The GM engineers weren't stupid. There must be a reason for the design and oil pooling at the base of the exhaust springs sounds as good as any theory so far. Somewhere in the GM archives there is a drawing or other engineering data to explain the design. We need to send Colvin into the catacombs to retrieve the info as he did for his books. Many of those engineering drawings tell quite a story if you read the notes. Even Colvin missed some.