Scat Crank Oiling Problem

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Model T Ford Forum: Forum 2015: Scat Crank Oiling Problem
Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Sunday, April 26, 2015 - 01:58 pm:

My buddy decided to build his latest motor with a stroker Scat crank and Sherman head. Car runs great! The problem is with the oiling. He opted for the non-drilled crank but added an oil pump and plumbed the mains figuring splash for the rods. The pan inspection plate is the finned aluminum version rather than the deep sump. Oil pump is from a Datsun B210 mounted where the generator would normally reside.

Start the motor and it registers a full 60 PSI for the oil. Drive for 5 to 10 minutes and the pressure drops to about 20 and fades from there to near zero. Ugly and alarming. Check the oil level and the dipstick (typical style from vendors) shows no oil. Bummer. Added oil and pressure came up but fell off again after a bit of driving. Drug the car home. Checked the oil and itís over full by the 3 quarts we added. Got the oil level back to normal, drove the car and had the same issues with pressure. Pulled the oil pickup line (it picks oil up from the bottom of the flywheel sump in the pan. Pickup looked fine and tucked nicely near the bottom of the sump. There are no magnets on the motor but 4 of the steel splashers the move the oil. Decided maybe they were working too well and removed them replacing them with a single spool on every other ring gear bolt. No significant change. It seems the oil is just not getting returned to the sump portion of the pan as it should.

The Scat crank counterweights require a bit of pan modification for clearance. The rear pan horseshoe needed to be split and the center removed as well as a section about 1 Ĺ inches long needed to be trimmed from the pan itself. I believe this is typical, at least for the stroker Scat. Could it be that the rear counterweight is throwing the oil back up and around the inside of the motor in front of the rear main rather than letting it return to the sump? Has anyone else experienced this? Any good ideas how to resolve? Our latest thoughts are to replace the finned bottom inspection plate with the aluminum spacer plate, ad a regular 4 deep steel inspection plate and below that a deep sump. We would drill return holes in the steel inspection plate to let the oil down into the lower sump which would also connect to the flywheel sump. The big question is how many and how big to make the holes in the inspection plate to permit adequate flow but still keep enough oil around to support the splash lubricated rods.

Has anyone else experienced this kind of problem? Any advice for how you resolved it? Looking for any good ideas.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Sunday, April 26, 2015 - 02:28 pm:

Off the cuff, you may need to use the deep oil pan and pickup from there. The flywheel keeps a lot of the oil slinging around even without magnets. There was an engine shown not too long ago that had a well off the passengers side bottom of the housing. Looked like a well to capture oil and hold it for the pump to pickup from.
Are you running a filter and adjustable regulator for flow control? While not an expert, 60's maybe more then you need depending on what the clearance/ type of bearings you have and RPM.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ed in California on Sunday, April 26, 2015 - 02:39 pm:

Try a Sherman deep sump oil pan.


http://www.mtfca.com/discus/messages/506218/515474.html?1423148966


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Sunday, April 26, 2015 - 02:40 pm:

Mark,

If we do the deep sump (and I think we need to) the oil pickup would go there rather than by the flywheel. The Datsun pump has a filter mount built in as well as a pressure control spring. We could likely tweak the spring to lower the presssure some but I've been running one of these pumps on my A crank speedster for several years and it has seemed happy.

If we do add the lower/deep sump, we want enough holes for oil to get to it while retaining enough in the normal inspection plate to take care of the rods.

With it seeming like we have more oil than we want flying around inside the engine, possibly we could make a couple about 1" holes in the flats between the rod dip areas on the original inspection plate that would be above the deep sump.

Thoughts?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Sunday, April 26, 2015 - 02:51 pm:

Walt
I am convinced that your problem is that ALL the oil is flying around in the engine, and so the pump becomes starving for oil
First I would get rid of ALL the stuff on the flywheel.
I have done a number of full pressure T conversions, and I guess that is why I go full pressure. I think you are running considerably more oil pressure than I would. I have one of those pumps and I added a additional oil pressure relief. I installed it so that the oil is dumped on top of the bands
I will send you a picture of a pan modification that will solve your immediate problem AND is almost invisible from the outside. It does create a new problem, but I have a solution for that as well.

What are you running for triple gear bearings? bushings or needle rollers. The answer to this will affect my recommendation

I'm not convinced that I like your proposed solution considering you have splash rods


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Sunday, April 26, 2015 - 02:54 pm:

Ed,

Thank you for the link, it covers this pretty well. My quick search didn't get me there so I appreciate you finding this.

Walt


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Sunday, April 26, 2015 - 02:57 pm:

Les,

I would certainly appreciate any options you have found. Feel free to post here or send a pm to me at wberdan comcast net

Traditional triple gears are being used.

Thank You,
Walt


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Sunday, April 26, 2015 - 03:11 pm:

Maybe that's a good idea on the windage tray. Might add an oil feed for each dipper trough.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth W DeLong on Sunday, April 26, 2015 - 03:21 pm:

Are you sure the oil pump is in good shape?? Bud in Wheeler,Mi.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Sunday, April 26, 2015 - 03:35 pm:

Bud,

Pump is new and while that isn't always proof of quality, it seems to work very normally when there is oil in the sump.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth W DeLong on Sunday, April 26, 2015 - 04:12 pm:

Walt,If the oil is not in the sump should it starve the pump after only a few seconds?? Is the pump adjustable?? Pressure is good but flow or volume is better?? Bud in Wheeler,Mi.PS,Can you hear the pump cavating?? Bud.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Sunday, April 26, 2015 - 04:29 pm:

Bud - Can't hear the pump cavitating. It does not starve after just a few seconds but after 5 to 10 minutes of driving the pressure drops off to about 20 PSI and continues to fade. Once the engine sits off for a few minutes, the oil get back in the sump and the pump works fine again. The problem is getting the oil back to the sump.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Bender Tulsa Oklahoma on Sunday, April 26, 2015 - 04:45 pm:

As Les has stated the pump pick up is starving for oil because of the rotation of the flywheel. This is cavitation of the pump due to aeration of the oil.

Larry Young built a pick up dam in the oil pan and this seems to have worked out well. Go here for a picture of his dam. http://mtfctulsa.com/Tech/plumbing.htm Oil is pushed into the dam. I have always used a deep sump and pick up oil there with a hose between it and the Ford pan.

The pump configuration you are using by-passes the oil back to the engine at the front of the engine. Most all of the oil is by-passed, in your case returning to the transmission area over the inspection cover with the dipper troughs.

Get rid of the cavitation and your problem should be solved. The rule of thumb is 10 psi per 1000 rpm. I change the spring out to get 40 psi when the oil is cold and as it warms up will drop to 30 psi.

Les I would like to see how you skin this cat if you don't mind.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Sunday, April 26, 2015 - 06:33 pm:


As you can see here, I keep the flywheel as much out of the oil as possible. The risk of this design is that now very little oil gets to the transmission. To solve this I do two things;
1. I drill a oil hole out of the back of the crankshaft (1/8" to 5/32" works well). It intersects the pressure oiling hole in the rear main.
I then drill the main transmission shaft for about 2 inches (same size hole as above). I then drill one 1/16" hole in the side to intersect. With this I now oil the transmission from the inside out.
2. As I stated above I usually dump the relief oil on top of the bands. Now on a full pressure engine there is not huge amounts of relief flow (at least from a VW pump and the end of the camshaft)

Mike I agree with your philosophy on oil pressure. On my first A cranked pressure oil counterbalanced engine I built in '70's I used a BIG camshaft and T springs with a Sherman head. The valves would float at about 4500 rpm, which made a great rev limiter


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Thursday, April 30, 2015 - 08:41 pm:

Update-

The existing finned inspection plate was modified slightly to provide a low dam (about 1/4") around the flat area under the center main, then a drain fitting was added and a hose to run oil back to the regular engine/trans sump immediately in front of the oil pickup. With some testing, probably 50 to 60 miles, the oil pressure drop off problem seems to be resolved.

Once this seemed resolved, the pressure regulator spring in the pump was replaced dropping the normal running pressure to about 35 PSI.

For now we believe the problems are resolved, if more changes are required later I'll let you know.

Of note, another friend with a stroker Scat crank used the spacer plate to lower the regular 4 dip inspection plate. He did some fairly serious shaping on the spacer piece to get clearance for the counterweights and he has not experienced any problems.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Thursday, April 30, 2015 - 08:44 pm:

Sorry, I meant to also thank those of you who contributed ideas for how to resolve this issue. Several very good ideas although some a little outside the scope of what the owner is wanting to tackle at this point.

There are lot's of sharp folks on this forum.

Thank You!


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