Cyl Head oil drain backs ?

I've been fighting an oil pressure problem for a while now. O/P fine at start up, lean into and the O/P drops after 20-30 seconds of WOT (6,400). When I lift the O/P comes right back. My thoughts are the oil can't get back down fast enough. Wondering if tapping the back of the head and adding bungs to the pan may solve my problem ? Thanks in advance !

Here's the basic's of what I have;

8-71
BT heads
Cometic's
A460 block
.055 restrictor in back, blocked up front
Kaase O/P
Armondo's 10qt. pan.
p/u tube 7/16" off the floor

Dave I think your pick up is to far off the bottom of the pan, I think it should be 1/4 inch..... to keep from cavitating....


Randy

What does it drop to? You Got a oil temp gauge? What oil?

I've tried the pick-up at 5/16, and 3/8, same end result. It drops to 10 (YIKES), and oil temps are HOT after a long run, 300*+. Using 20w-50 Mobil1. The o/p is down when real hot, but still very liveable (45lbs.). I had an oil cooler last year, same o/p troubles. It's not on-line this year, wanted to see if it made any difference. Below is a short vid, the o/p guage is to the right of the speedo, you can get a good idea of what it does.

https://www.youtube.com/watch?v=XfijJDKOlfQ

I'm thinking it may not be a drain back issue [1] Looks like the pressure dropped as soon as you stabbed it. [2] With the small .055" restrictor to the top there shouldn't be a ton of oil up there.
It may not be the case but it acts more like a windage deal to me. 300* is more than I'd like to see.....what is the pressure like with the oil 200*ish?

I'm thinking Lem is onto something with aeration.

Pressure is about 10lbs. better with the cooler oil. Areation is something that's been brought up to me. I was told to pull the pan and fill to the windage tray, counting how many qts. it takes. I have tried to run it at normal, 1 qt. low, and 1qt. high. Same darn problem.

I'm not happy with the oil temps either. I need a btter oil cooler.

Actuallly I don't see the pressure drop after the start, you see the guage is 3/4, then like someone flipped a switch it drop 15-20psi ???

If/when it is windage.....that will raise the oil temp. Does the pan have 'kickouts' at the pan rail? How deep is the pan ft/rear? What does the tray in the pan look like? Stroke?

Daytonatunnel wrote:Actuallly I don't see the pressure drop after the start, you see the guage is 3/4, then like someone flipped a switch it drop 15-20psi ???

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So it drops before the start? We really can't tell much from the film.

INTERESTING....oil temp climb when you have windage ?????

Pan is Armondo's jetboat oil pan. No kickouts, can't remember but like 7.5" n 9/5" in the rear. Springloaded (very light) trap doors, windage tray is flat with some louvering and bolts to the pan. 4.3 stroke, 547 ci currently.

Lem Evans wrote:

Daytonatunnel wrote:Actuallly I don't see the pressure drop after the start, you see the guage is 3/4, then like someone flipped a switch it drop 15-20psi ???

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So it drops before the start? We really can't tell much from the film.

Pressure is fine, then about half way through the clip you see is drop 15psi like a switch. Sorry, it wasn't the smoothest water

I know a guy that installed a remote oil filter block but plumbed it backwards. Fast drop in oil pressure at higher rpm. Just a thought.

I've had the same thought...it may be a delivery problem. One thing for sure it's darn hard to fix one over the 'net'.
The nice part about it...it won't take many $s to put a -8AN or 1/2" rubber line from the heads to the pan....if you do so please report back.

No remote oil system. I will save this thread and post up my findings. It'll be 7 months from now, as it looks like our boating season (if you can cal it that) is over here in the N/W.

I agree, it'll be an inexpensive attempt. I'm also going to put the pan on the work bench and see how high 10 qts. really is inside the pan. Questions, how far down from the pan flange should the oil level be ? Thanks for the help guys !!!

I like the idea others mention of the drain lines from the head to the pan, it has to be a better way to drain the oil, especially when the head's drain becomes overwhelmed! Is the coolant for the oil, fresh water, circulated water or simply air? If the engine's upper areas are retaining an elevated amount of oil, then the oil that resides in the pan becomes less by volume and easier to heat. The way that son-of-a-bitch accelerates, the oil sump is near or at the rear of the pan .... isn't it?

Dave.

The p/u tube is about 2" from the back of the pan. The engine is cooled by lake water. The oil cooler was also cooled by lake water, but I took it off line to remove any doubt. And thanks for the comp, it pulls well

I had some drain back issues on my last build, at the end of the first 1/4 mile run my oil pressure was at ZERO - immediately shut it down and coasted to the return road! I opened the hood for a quick check, and found both of my valve covers leaking oil at the back. I then checked the oil level, which looked OK, started it up, plenty of oil pressure again. After I checked all the valve cover bolts, tightened them more than they should be, I went another 1/4 mile run - same thing again, loaded it up and went home. On inspection, I found that the oil drains, as small as they are were even more restricted by a very poor line up with the hole in the head gasket (BTY the valve covers are capable of holding nearly four quarts of oil)! I "persuaded" the holes in the head gaskets to line up, and installed a set of Smith Brothers "restrictor" push rods. That seemed to take care of my problems. On my new build, I decided to add the oil return lines at the back of the heads. I did my in -10 braided line (overkill? maybe), I drilled and tapped the back of the head at the lowest point possible, installed -10 90 degree elbows, and ran them into -10 45 degree elbows about an inch below the pan rails. Be sure that they don't interfere with anything, such as a starter motor (don't ask how I know this - GROAN). I haven't had any drain back problems since then.

Wayne (SAWDOFF) Pearce

Thanks for the first hand experience Wayne. I think I'll add the drainbacks, and carefully check the head gasket alingnment and hole size upon re-asembly. Thanks again guys !!!