All Small Six Drilling out oil drain back holes in 200ci block

[Goldie]

Hi guys! It's me again! Still dealing with oil issues in our recent performance 200/aussie head/yella terra RR combo. No matter what we've tried, oil is still being sucked up into the carburetor. The valve cover fills with oil and the oil light comes on, indicating the pan is low on oil. Leakdown test has been done. All is good there. We have tried a combination of breathers and PCV valves. We have tried two different stock oil pumps. Oil pressure is fine (slightly high) at 27psi hot idle. We have also put in 60% restricted Smith Bros. pushrods to help keep some oil below the valve cover. We have tried a thinner viscosity oil. Nothing has helped. We have taken off the head, and don't see any visible restrictions. So, we will be pulling the engine and opening up the drain back holes in the block to help allow the oil to drain back to the pan. Do any of you know if there is a specific "spec" or bore diameter that we should use when opening up these ports? Don't want to assume that any amount will be good, or that "too much is just right". We have a ton of $$ into this engine and certainly don't want to destroy it.

Many thanks!

 

[CNC-Dude]

Is there evidence of oil pooling and collecting in the head and not returning to the pan in a timely manner....?

 

[Goldie]

Is there evidence of oil pooling and collecting in the head and not returning to the pan in a timely manner....?

Oh yes! Oil fills the valve cover and isn’t returning before PCV valve sucks it up through carb line. We have tried many fixes and even made custom baffles for the finned alum valve cover that was originally without baffles. I have posted about this issue a few times and we are just beside ourselves trying to get resolution to the problem. The car, otherwise runs strong with tons of power.

 

[CNC-Dude]

Ok, I'm going to guess that the head gasket is partially or completely blocking some of the drain back holes. It might even have been possible to install the gasket backwards causing this. Which Oz head are you using, the 2V or Crossflow...?

 

[Goldie]

Ok, I'm going to guess that the head gasket is partially or completely blocking some of the drain back holes. It might even have been possible to install the gasket backwards causing this. Which Oz head are you using, the 2V or Crossflow...?

Head has been removed and there is no evidence that it was installed backward or blocking any of the passages. We have the 2V cast Aussie head. with Aussie intake.

 

[CNC-Dude]

It's possible that sludge has built up inside the drain back passages in the block that might not have gotten dissolved/removed when the block was machined at the machine shop. I'm going to assume the whole engine was a complete teardown and run through the machine shop to be bored, decked, etc....

 

[drag-200stang]

I wish I could tell you make hole this big and make that this size but I cannot and cannot say it will solve your issue, it will help. Pay close attention where the oil passages are, and a square hole will flow more and keep you farther away from the passages. This is something done during block prep.
Chamfering the head push rod holes on top will also help.
May need to vent crank case from the crank case to bypass the drain back lifter area and valve cover.
Sorry that you are having so much trouble.
CNC the problem is that this engine had crank case venting by way of road draft tube, when they deleted the road draft tube they should of made the three small oil drain back holes more and bigger. The oil cannot drain back now competing with blowby. The big six has what 6 large and one or two small drain back holes.

 

[100_2023]

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[Goldie]

The block was hot tanked, decked, over-bored & honed for chromemoly rings, & align honed. New freeze plugs, cam bearings & oil galley plugs were installed. Forged pistons were weight matched. Forged rods were resized & machined for ARP rod bolts, weight matched, balanced end for end, shot peened & polished. Complete reciprocating assembly was balanced. Camshaft was advanced 2 degrees when installed with new thrust plate, wedding ring & dowel pin. Oil feed from block to head to stock rocker arm pedestal area was plugged by an allen-headed screw in the block about 1/8" below the deck. Head was decked slightly. Hardened seats were installed. SSI stainless steel 1.75" intake valves & 1.50" exhaust valves were installed. The intake valves have a 30 degree back cut on them & a 3 angle valve seat job was done. K-liner bronze valve guides were installed along with viton valve guide seals. The springs are $330 Crower double springs with their retainers & locks. No expense was spared with this engine. I had it built for a 1980 Foxbody Mustang to drag race. I never installed the engine in the car or fired it up to break it in. I had a good bit more money in this engine than I sold it for. It was built by a company in OKC that builds a lot of racing engines, rare nostalgic engines & industrial engines. They have built engines for me & all 10 of the HiPo Ford 6 cylinder heads that I have sold on here.

Darrell R. Miller

Darrell, thanks for explaining all of this to the forum members. I’m sure they will be able to see that this wasn’t put together by some fly by night outfit. We wouldn’t have purchased it if it was. We will get it. It’s just very frustrating. Thanks for all your help along the way.

 

[pmuller9]

Don’t pull the engine out just yet.
Pull the distributor and run the oil pump with a drill and see how much oil is coming out of the lifters.
You can also watch how fast the lifter gallery fills with oil.

 

[chad]

Post over on the Oz forum? Guys more familiar w/your system who've solved?

 

[Goldie]

Post over on the Oz forum? Guys more familiar w/your system who've solved?

Thanks Chad. I've reached out to a few of them privately.

 

[Goldie]

Don’t pull the engine out just yet.
Pull the distributor and run the oil pump with a drill and see how much oil is coming out of the lifters.
You can also watch how fast the lifter gallery fills with oil.

Excellent idea! Thank you for, yet again, another great suggestion. We'll let you know how that goes. Working on a couple of customer's cars today, so might not be able to get to it until this evening (or tomorrow).

 

[Goldie]

It's possible that sludge has built up inside the drain back passages in the block that might not have gotten dissolved/removed when the block was machined at the machine shop. I'm going to assume the whole engine was a complete teardown and run through the machine shop to be bored, decked, etc....

Not likely CNC-Dude. See Super4ord's response above. We purchased this engine from him. It was built by a reputable shop that has built race engines for Super4ord for years.

 

[drag-200stang]

Don’t pull the engine out just yet.
Pull the distributor and run the oil pump with a drill and see how much oil is coming out of the lifters.
You can also watch how fast the lifter gallery fills with oil.

That is a great idea to see if the lifters are leaking too much oil for various reasons, but it will not simulate blowby competition. Not sure if I would pull the engine yet.
I also could not believe that with 12 head pushrod holes to drain oil, maybe the larger that stock pushrod and if the engine is tilted down a lot in the back that the oil is pooling higher there because the oil cannot flow down fast enough at the rear pushrod holes, then of course the old blowby competition, but it is possible.

 

[pmuller9]

What I suspect is that there is too much oil to drain past the 3 holes in bottom of the lifter gallery that lead to the crankcase.
The lifter gallery is filling up first then the valve cover.
Enough oil is being transferred from the oil pan to put the oil light on at 3 miles.
If you remove the valve cover when the engine is running, it will squirt oil out of the engine compartment into the shop.

That is way too much oil.
I’m starting to suspect the lifters.

Oil pressure ranges between 25 and 55 psi

The 3 mile run is at cruising, light throttle conditions so there is minimum blow by.
The leak down results were good.

 

[drag-200stang]

What I suspect is that there is too much oil to drain past the 3 holes in bottom of the lifter gallery that lead to the crankcase.
The lifter gallery is filling up first then the valve cover.
Enough oil is being transferred from the oil pan to put the oil light on at 3 miles.

Yes, that is definitely the oil pressure problem, and I also think that is leading to the valve cover filling up. I have always opened up the three drain back holes and chamfer the top of the pushrod holes and with 3/8 pushrods have not had a problem, but I am using the stock shaft oiling.
But now with 15 LBS. boost it is now a problem a big problem. New build will have the fuel pump opening opened up and a large, tall riser with baffling to vent crank case.

 

[Frank]

New build will have the fuel pump opening opened up and a large, tall riser with baffling to vent crank case.

Yes. Any arrangement that releases the blowby from the block is better for OHV oil control and potential contamination of rocker area from acids/water vapor. All industrial-grade engines have engine block blowby venting.
This is still not the cause of Goldie's issue, considering the good leakdown test.

 

[78_200_C4]

Once working in a shop in the 70's a 283 Chevy had a serious problem of too much oil to the top end which caused the engine which we just put rings into to smoke.
The boss had me stuff pipe cleaners in the push rods. The problem went away.
It sounds like the problem is the Yella-Terra RR setup not the 200 block oil drain back..

 

[Goldie]

Thanks 78_200_C4. We have also restricted flow through the pushrods by adding 60% restricted pushrods by Smith Bros. Problem still exists. We have an option of running 80% restricted pushrods if we have to but they will need to be made. We really have tried everything.

Put a drill to the oil pump yesterday with the head off to watch oil flow and drain back. Oil pressure is a pretty consistent 50psi. Front facing cylinders are emptying much faster than the rear two. Cyl 6 just sits in a pool. Add the inertia of traveling forward, and that puts even more oil toward the back of the engine. We also noticed seepage at the plug at the back of the block that has been added to accommodate the oil thru pushrods. That will also be fixed.

Still not 100% sure, but leaning toward putting the 1/2” drain plug toward the back of the block between cyl 5&6 and tie it directly in to the oil pan.