Resucitar la carrera - Rebuilding the 1968

[RHough]

Make sure the mounts themselves are perfect, the HD factory ones are miles better than the urethane jobs...
The EMPI solid mount//trans strap setup fits like hell but it does work,once you can get it to fit.

Frame horns without a brace can easily get tweaked by reasonable power levels...
Remember, it was designed for ~60HP with a tailwind.

You should be able to tell what's bent with the engine out.

I wish I had some measuring points, like wishbone to top shock mount etc. Maybe use my digital level to compare the frame horn holes to the torsion bar tube.

How much torque is on those bolts? I have the down legs for a truss bar that I can add if I can get the bolts out. Might be able to use the turnbuckles to square it all up ...

I am working in a carport in a trailer park ... so the try to bend it back by eyeball thing fits ... (no offense to other trailer park trash intended) ... We like it here ...

[Piledriver]

Unless the car has been whacked badly the luggage tray floor is a pretty good reference.
A tape measure should be sufficient.
Fight the OCD, no laser range finders or optical table needed...

you are going to need a kafer brace anyway.
I made my sons setup adjustable for good reason.

I have a Ryobi 18v impact I use for most things... 4 Amp/hour batteries go awhile.

[RHough]

Paying attention to the oil system is a hobby ... I'm not really obsessed

The places that need oil should have all they need at any rpm or temperature. The oil in the sump should cover the oil pickup at all times. The oil should stay in the sump at high rpm or under g-loads.

We've got a good oil supply from the pickup to the pump.

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The normal oil level fills the case higher than I thought. I don't know if the new cases are different but the oil off the crank has no direct shot at the open end of the pushrod tube from above the tappets. The tubes *are* open to the sump.

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We can baffle the pushrod tube openings and separate the sump from the cyclone of air and oil twirling around the crank with a windage tray. All the oil has to make it back into the sump past the plate so we can't seal it off completely. The other way oil can escape the sump is under cornering loads ... 1G is like tilting the engine at 45° to one side. That will cover the pushrod tubes and your valve covers become the new sump ... not good..

Here is the part of the solution we are using on this engine. Windage tray to block direct shot from sump to the tube openings and windage tubes to create a dam at the tubes.

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Now all the oil is above the windage tray and needs to get back into the sump. There are holes in the centre of the tray and clearance at the sides of the case. In theory any oil trapped on the side of the case by windage or G forces will find a way back to the sump.

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If the sump is not full of oil we have less to worry about from G forces. If there is less air in the case we have less windage in the first place ...

The dry sump system should take care of getting oil out of the case and a good crankcase vent system should keep the windage to a minimum.

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[Piledriver]

I still think that really cool sump tank needs to grow by 8 inches or ~3 quarts.
Running out of oil at high RPM will suck, and the accusump is best only intentionally used on startup.
I'm not sure how its going to work as a crutch for an almost certainly too small dry sump tank.

There are ways to put level sensors in the tank, you could rig one up and see if the level was below a certain point and shut down or at least have it scream at you.

I just don't want to see you eat another build.

[RHough]

This is the oil pump cover that came off the engine that died ... it is cast iron it was wearing ...

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This is the new dry sump pump it is pretty

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These are two oil pump covers

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One is Steel

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[Piledriver]

The aluminum one would be worn worse than that by the time the cam was broken in.

[RHough]

I still think that really cool sump tank needs to grow by 8 inches or ~3 quarts.
Running out of oil at high RPM will suck, and the accusump is best only intentionally used on startup.
I'm not sure how its going to work as a crutch for an almost certainly too small dry sump tank.

You might be right.

3-3.5 litres of oil in the deep sump engine was plenty of oil. Why does moving the oil from inside the engine to outside the engine require more oil? How can it run out of oil?

If the engine pumps its valve covers full of oil or pumps oil into a catch tank that is no reason to use a bigger tank. 0The only reason I can think of is to allow more time for the oil and air to separate.

If I read it right the 26mm pump is 4 - 4.5 Gal Per Min? So the 21mm pump is about 3.6 Gal/Min. The 4 quart system circulates the oil every 16.5 seconds, a 7 quart system every 29 seconds. The stock system with 3 quarts in the engine was running the oil through the pump every 10 seconds.

My gut instinct says that hot oil deaerates faster than cold oil. Getting the oil up to temperature faster is a primary concern.

I suppose I can run a test with a bowl of oil and and a whisk to see what how fast the oil de-aerates over time. Might be fun ... Honey ... can I use the MixMaster?

Heat oil to 180-200° run mixer to aerate the oil. Time the escape of the bubbles?

We don't need all the air out of all the oil in the tank, just the next second's supply at the tank outlet. Tall tanks wider at the top seem to work. Easy enough to add capacity without having to relocate anything if I need to.

Or add an air-oil separator to the return line: http://www.spintric.com/index.htm

[Piledriver]

Hey, its all in the name of performance// er, science, right?
They make thermal wraps for oil tanks and hoses can be insulated.

Actually, if there is any chance the engine CAN fill up the valve covers or have a large qty of oel not in the tank, it IS an excuse for more oil, and you need room to store it when its all home.
No oil in tank == very very bad, under absolutely any circumstances.
(Thus the danger of a full case on startup and related need for oil level interlock and electric pump or cutoff valve etc)

I have been eyeing a competing deareating unit likely similar to that, looks very simple...
Its really just an intentionally internally leaky centrifugal pump, particularly on the air outlet side.
I posted a vid of it awhile back, cutaways were shown for some reason...

Connects to scavenge:Liquid is heavier, gets flung to OD and out, bubbles "rise" to center outlet.
The scavenge pump still does the oil/air movement work.
I doesn't look like it would take much power or be hard to fab, but you could probably run it too fast and have it act as a fine blender.
May need an additional stage to push the oil or air to the tank? (probably not)
Haven't built one. Yet.
There's probably an ideal RPM rnge based on oil viscosity/temperature.

[RHough]

Hey, its all in the name of performance// er, science, right?
They make thermal wraps for oil tanks and hoses can be insulated.

Actually, if there is any chance the engine CAN fill up the valve covers or have a large qty of oel not in the tank, it IS an excuse for more oil, and you need room to store it when its all home.
No oil in tank == very very bad, under absolutely any circumstances.
(Thus the danger of a full case on startup and related need for oil level interlock and electric pump or cutoff valve etc)

I have been eyeing a competing deareating unit likely similar to that, looks very simple...
Its really just an intentionally internally leaky centrifugal pump, particularly on the air outlet side.
I posted a vid of it awhile back, cutaways were shown for some reason...

Connects to scavenge:Liquid is heavier, gets flung to OD and out, bubbles "rise" to center outlet.
The scavenge pump still does the oil/air movement work.
I doesn't look like it would take much power or be hard to fab, but you could probably run it too fast and have it act as a fine blender.
May need an additional stage to push the oil or air to the tank? (probably not)
Haven't built one. Yet.
There's probably an ideal RPM rnge based on oil viscosity/temperature.

I've been doing some reading. One of the considerations is how much air needs to be removed from a dry sump system. Another is time that oil can collect in the engine before getting scavenged.

I found this rule of thumb: Longest corner in seconds x 2 x volume of oil moved per second = minimum capacity of reservoir.

For the 3.6 Gal/Min that is 14.4 qts/min or .24 qt/sec
15 second corner x 2 x 0.24 = 7.2 qts
10 second corner x 2 x 0.24 = 4.8 qts
7 second corner x 2 x 0.24 = 3.4 qts

Looking at laps of the local road course no corner is longer than 9 seconds from turn-in to track out, so maybe 70% of that time pulling enough G's to hold oil away from the pickup.

Another consideration that is somewhat related to air separation requirements is how much air needs to come out. For a V8 with 3-4 scavenge pumps (2 pan + 1 each valve cover) and each pump sized to scavenge 100% the total scavenge capacity is 3-400% of total flow. i.e. for every qt pumped into the engine 3-4 qts of air/oil is coming back to the tank. The return is more air than oil.

In the single scavenge section we are using and assuming both sides are 100% the ratio is 26/21 or 124% return not 300%. For 26mm = 4.2 gal/min 21mm = 3.4 ga/min so we need to remove 0.8 gal/min of air. In airflow terms that is about 0.10 CFM. .1 CFM is not much. A 3/8" hose 3ft long flows .1 CFM with 0 pressure loss.

So ... In the interest of science ...

The oil sump in the case has these dimensions 9"L x 10"W x 1.5" to full mark on dipstick 2.5" to bottom of PR tube openings. G loads can be estimated by tilting the engine. When engine is tilted so the oil pick up and PR tubes are level, oil will start draining into the valve cover. There is a volume of oil in the case that is below both the PR tube and the pickup as shown by the red line below. (green is normal oil level). This is about a .5 G load.

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This trapped volume is at most 9" x 5" x 2" = 90 cu in or 1.5 qts

As more oil is added the pickup can scavenge it limiting the amount that pools in the valve cover when the g load is over .5 or so.

I'f the car pulls over .5 g for the entire 7 seconds it will have pumped 1.75 qts of oil into the engine. 1.5 is trapped away from the pickup so .25qt can make it into the valve cover.

Lets say we have 1.75 qts in the engine after a long corner. We still have oil in the tank and the scavenge pump will pump those 1.75 qts back into the tank in 6.25 seconds.

I can see a quart of oil remaining in the case sloshing around past the pickup during an autocross run. The design of the engine with a flat case floor is a challenge. On the race course the idea is to have maximum G's all the time so the system will never work as if the engine is level. The question becomes the amount of time the car is pulling enough g-force to starve the pickup and how much oil is trapped by those forces. The oil level in the tank will drop by that amount and return to normal when the g-forces are removed.

I'm going to assume that 1.5 quarts will stay in the engine while racing. So the tank has to work over that range. Adding tank volume makes all of this less critical ...

I still think I'll be okay, but your concerns got me to investigate further. Thanks!

The 2qt Accusump will cover 100% loss of oil flow from the tank for 8.3 seconds based on the .24 qt/sec rate.

Maybe just don't drive it hard?

[FJCamper]

Randy,

You have inspired us to try a steel oil pump cover. Aluminum does wear too much with those steel gears up against it. I always thought that if the factory used steel (VW & Porsche) then so should we. But I'd left the CB pump covers alone because I didn't want to mess with success.

You've done some impressive and probably very accurate brainstorming on the oil system. I personally think you'll be okay with the murdercycle oil tank. Remember, the 550A tank was 6 qts.

Oil "pooling" in the Type 1 valve covers increases in the 3-4 cylinder side with rpm as crank windage literally blows it toward that side, car sitting still.

Windage pushrod tubes and a windage tray cut the oil windage toward 3 & 4 in half. We observed this on the engine stand with the valve cover window.

Oil to cyls 1 & 2 is centrifugal, only a concern while cornering hard. But, having said that, the 1-2 cylinder side valve cover will still pool at least a quarter to a third of a quart of oil between 3000-5000 RPM because we observed this with the valve cover window. The pushrod tubes do not drain the oil back fast enough.

A nitpicking detail but one we've practiced is using the stock valve covers rather than the big aluminum ones because the stocks hold less oil!

And we've absolutely proven to ourselves that if we use the CB pump, and have good Total Seal piston rings, crankcase pressure is reduced, blowby almost becomes a nonproblem, and we were able to race without, I say again, without vented valve covers.

We have been able to vent just off the alternator stand to a plastic catch tank, and after hours of continuous racing, a test drain of the tank just yields a few ounces of reconstituted liquid oil from foam and vapor.

For a time, we were running just one valve cover vent, on the 3-4 side, but began to worry maybe we were encouraging pooling by reducing pressure in the valve cover that might otherwise help push oil drainage back to the engine.

All I can tell you is with a three-gallon tank, proper oil baffles in the tank, and the CB pump, we are good. No oil lights at any time.

FJC

[Piledriver]

How much oil does that tank actually hold?
(full to the top and to drainback level)

[RHough]

How much oil does that tank actually hold?
(full to the top and to drainback level)

I get the tank back from the welder today. This exchange has been great. I'm going to set it up and measure to the low mark on the dipstick, the high mark, to the internal overflow, and to the point oil comes out the vent.

My memory says that after draining the sump and tank on the CB750's the system took 4 quarts (Litres) w/o a filter and 4.5 quarts if the filter was changed. I think we dumped 4 quarts into the tank, then ran the engine and topped off as needed ... Now that you got me worried it turns out the drill was to put 3 quarts in, then top up to about 3.7 or so.

I'll be very careful to fill the tank, crank the engine to prime the pump then check the level as soon as the filter and Accusump have a chance to fill.

I think total capacity will be:
3.5 L Tank
1.0 L lines and Filter
2.0 L Accusump
6.5 L Total

Off to pick up fittings ...

Edit:
3.8 litres to overflow
2.2 L to "full" mark on dipstick
1.2 L to "add" mark

So about a litre less than I remembered. So I'm pushing my luck a bit. However it is still more oil total than the engine with a 1.5Qt deep sump.

[RHough]

Randy,

You have inspired us to try a steel oil pump cover. Aluminum does wear too much with those steel gears up against it. I always thought that if the factory used steel (VW & Porsche) then so should we. But I'd left the CB pump covers alone because I didn't want to mess with success.

...

A nitpicking detail but one we've practiced is using the stock valve covers rather than the big aluminum ones because the stocks hold less oil!

And we've absolutely proven to ourselves that if we use the CB pump, and have good Total Seal piston rings, crankcase pressure is reduced, blowby almost becomes a nonproblem, and we were able to race without, I say again, without vented valve covers.

We have been able to vent just off the alternator stand to a plastic catch tank, and after hours of continuous racing, a test drain of the tank just yields a few ounces of reconstituted liquid oil from foam and vapor.

For a time, we were running just one valve cover vent, on the 3-4 side, but began to worry maybe we were encouraging pooling by reducing pressure in the valve cover that might otherwise help push oil drainage back to the engine.

All I can tell you is with a three-gallon tank, proper oil baffles in the tank, and the CB pump, we are good. No oil lights at any time.

FJC

I'm not married to the big valve covers or to valve cover vents. I'd like to pull neg pressure in the cases.

During the OA meeting today we were staring at the cases and it occurs that the 3/4 side filling with oil might not be from oil getting pushed up the tubes but just oil prevented from returning from that side by the windage?

Looking at the case internals it looks like the 1-3 side and the 2-4 side are out of phase in that the total case volume does not change but the volume transfers from one side of the centre web to the other? Does this create a pressure pulse say at the fuel pump flange? Would a Krankvent(tm) plumbed to a fitting on a fuel pump block-off plate try to evacuate the case? If so then a second fitting in the 1-3 side of the center web should also see a pressure pulse that is 180° out of phase with the 2-4 side?

Evacuating the case is all kinds of good so getting that figured is a high priority. The tank vent will go on the case side of the Krankvents(tm) the filler vent and other side of the case system will go to an air cleaner housing for fresh air intake.

Does that make sense? I edited your Krankvent system moving the valve cover vents to the case and adding the oil tank vent.

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[Piledriver]

Set the 3/4 side up with a vent with a check valve so it only serves as a purge.
I have an adjustable vacuum break feeding it.
1/2 side is plugged.

Valve guide leakage happens, and can be used to good effect.
On T4s, Len Hoffman and Jake recommended no breathers at heads for that reason, they are counterproductive.
The physics are no different on T1s, they just didn't race T1s.

I only suck on the case, through a pair of woven SS ribbon pot scrubbers in the case chimney.
On a T1 that would be equivalent to ~in the gen stand, above the baffle, the case heat is critical to keep those air/oil separators from getting plugged up with vaseline.

I used restricted manifold vacuum w/check valves as a vacuum source, has a 1L tank at the moment, may go larger if I ever find a cheap light large vacuum accumulator can. (1 gallon commercial soup cans have been considered, up by trans)

[RHough]

Unless the car has been whacked badly the luggage tray floor is a pretty good reference.
A tape measure should be sufficient.
Fight the OCD, no laser range finders or optical table needed...

you are going to need a kafer brace anyway.
I made my sons setup adjustable for good reason.

I have a Ryobi 18v impact I use for most things... 4 Amp/hour batteries go awhile.

Copy the Ryobi impact ... I did a PB blaster soak while I found the 27mm impact socket and they came right out.

Wow ... the horns are noodles! They sprung out of line when the bolts came out. I thought I was hooped but a short pry bar and not much pressure got the holes aligned to put the bolts back in. The lower mounts for the kafer bar went right in and I'll be able to 'tune" the engine position with a tiny pre-load.

I may have to fight the heater ducts around the truss but after seeing the flex in the horns you are right ... it needed the truss.

Baby steps ...