i'm going to be putting together a 383, and i'm wondering what you guys have experienced with plugging the 8 drainback holes in the lifter valley. my reasoning for wanting to do this is to keep the oil coming off of the lifters from draining into the rotating assembly. in theory, this should improve power output by not allowing oil to enter the spinning rotating assembly, increasing rotating mass. since i'll be running a hydraulic roller cam, the lack of splash oiling out of those 8 holes shouldnt be a huge issue as there will be oil coming off of the lifters already. what are your thoughts on this?

 

Unless your wanting to turn really high rpms, that windage control wont make a huge difference in power output. honestly, I don't think I would do it unless I was racing it, theres probably a reason those drainholes are there.

just my 2 cents-

Eric

 

i'm not looking for a huge difference anywhere. i wouldnt expect one from a total investment of 1 1/4" pipe tap and 8 1/4" pipe plugs. when you add together a bunch of little differences, they will add up to a big difference.

 

you don't plug them, you just use standoffs. You still want pressure to be able to flow back and forth.
With a roller cam it's acceptable, but as mentioned, unless you're turning high RPM's the difference is negligible. Lack of oil (or the possibility) is enough reason for me to avoid doing this mod (myself at least).

 

Unfortunately if you have a roller cam block you can't use the commercially made stand offs. I bought a set from summit and can't use them. (anyone want to buy them from me) They are too tall and interfere with the sheet metal roller lifter hold down unit. I went and got four 2-1/2" long 1/4" brass pipe nipples and cut them in half. They will let the bottom end vent and clear the spider easily while controlling oil drain back.

I'm not doing this for any horsepower gains. Since I have a roller block and don't need the extra lubrication on the cam lobes I'm doing this to help with oil control so the rings don't have that extra oil to try and deal with. I'm also painting the lifter valley, the block behind the timing cover, and the top of the cylinder heads with high temp electric motor varnish to help promote quicker oil drain back. If I had a flat tappet cam I'd never plug these holes since the oil companies have taken out the ZDDP that used to help prevent cam and lifter wear and the extra oil might just help with preventing that.

 

You've got 2 great big holes in the front, and 2 great big holes in the back that are going to equalize pressure just fine.

 

Alright. Then why do "they" use standoffs (ie "four 2-1/2" long 1/4" brass pipe nipples and cut them in half. ") instead of plugs? Any ideas?

 

If you're going to do that, you might as well grind/sand the lifter valley smooth and port out the front and rear drain back holes.

Personally unless you're building a high rpm race motor I wouldn't bother doing all that.

 

Actually I did that... There's a lot of casting flash in those big holes. I ground them out nice and smooth, and just cleaned up the lifter valley and painted it. I think I baked the paint on too....
Just because it was easy, not because I was hoping for big gains.

 

Sonix, are you doing the standoffs in a street driven engine? i've built a lot of engines for other people, and nobody has ever wanted this done. i'm building the first engine for myself that i have built in several years. i know i'm not going to build a top fueler motor using stock parts this way, but every little gain or improvement is worth it at this point. i've got a bare block on the engine stand now, and if its only going to cost me $20 or less to help keep the oil out of the rotating assembly, and more effectively put it back in the pan, then i'm all for it.

it is a factory roller block, and i'm planning on running stock style lifters and spider. i noticed the holes could potentially be covered by the spider, that's why i mentioned the pipe plugs. Moroso offers them in their lifter valley screen kit. http://store.summitracing.com/partde...0&autoview=sku

 

I plug them and use screens in the ends, more for keeping parts from getting into the pan if something fails in the valvetrain than for oil control.

 

no no, i'm not using standoffs. I just meant I did the other things, ie. sanding and painting the lifter valley, porting up the end drains, magnets near the end drains (no screens though), etc.

 

I run high rpms. In my smaller BBC engines, I was using lifter valley screens. If I have something big enough in the lifter valley, I'd prefer to have it sitting in the bottom of the pan. If you think a screen is good for capturing chunks of metal like valve springs, keepers etc, you have more serious problems to worry about.

I have magnets glued in the head oil drains to catch anything but that's mainly while I'm working on the engine with the covers off. Small metal filings such as copper and aluminum won't be stopped by magnets. That's why I run a System 1 oil filter so I can check for any metal from time to time.

My current engine has no oil restrictions. No screens, no plugs to stop or slow the oil return to the pan. I want to get the oil back into the pan as fast as possible. Redirecting the oil to the front or rear of the lifter valley before allowing it to drain back into the pan takes time. Stopping the oil from dripping back onto the crank may stop some windage but I doubt you'll see any performance gain even on a dyno. A BBC has a large oil drain at the front of the lifter valley. Under hard acceleration, all the oil goes to the back.

I run a 7 quart pan and I use an accumulator. At the end of a 1/4 mile run, most of the oil is in the top end of the engine. The accumulator kicks in just as I start to slow down. I still can't get it back into the pan fast enough.

 

[QUOTE=alloy;3969051 If I had a flat tappet cam I'd never plug these holes since the oil companies have taken out the ZDDP that used to help prevent cam and lifter wear and the extra oil might just help with preventing that.[/QUOTE]

They haven't removed it just cut it back by about half between sh and sj rated oils(most companies) although it is a good hypoid lube,it's not as quintessential as correct spring pressures.