Perfconn......Do you have any suggestions for ways of keeping/getting oil back down into the pan on a wet sump, 23*, flat tappet, (IMCA legal) engine? We're already running drain down lines off each head dwon to the pan.
The best thing you can do is open up all the oil drainback holes in the block and heads before building the engine.I know what you are talking about on the external lines.There is a big engine builder in the midwest that does that but I have never saw the need to do it.Of course it helps when you want to charge $22,500 for an engine.
In a wet sump, high rpm application a lot of the drain back problems occur when pressure builds up in the bottom end of the engine creating positive pressure below the drain backs preventing drain back. If you are running low drag oil rings you might need to prep your bores and top 2 rings and piston some to keep from allowing cylinder pressure into the pan.
You should also employ a top quality stem seal, I use the blue viton seals with positive pressure springs on the top. I also tighten up valve stem clearances when I can to less than .001" using phospor-bronze guides and a very agressive cross hatch on the guide hone finish as well as the valve stem.
You can also block most of the holes with oil in the valley with screens and valley baffles, as the oil will hang there even with large drain backs. I normally put at least 2 vent tubes in the lifter valley so the bottom end can breathe better.
Proper break-in procedures can also ensure a positive ring seal the results in better drain back. You can tell an engine with good seal when you don't see any smoke out of the VC breathers, in rare cases properly prepared engines will pull vacuum from the breathers if you measure it and in this case you should run a Peterson Pop-off valve to relieve the vacuum under deceleration or you will burn pistons.
If you run a roller cam, you can limit oil to the heads by ordering solid pushrods and if you need some oil up top it is easy to use spray bar valve covers and putting in small jets and you will only get a small amount of oil in the heads. You have to consider that most pushrod holes are much larger than the jets in a good set of Valve covers.
Not sure of your rules but header evac. systems work great on dry sump engines, plumbing can be tuff and if you are blowing oil already I don't recommend it as you can start a fire in the headers.
If you need some oiler valve covers contact Mike Laws at BLP = Bo-Laws Performance and get the ones with a jet in behind the AN Fitting. He has some on the shelf and will custom make anything you want.
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