Pinto Building - Head Draining

[BeerBudgetRacing]

Maybe this has been discussed before but my searches have not located it.

So, I have 2 different engines I'm rebuilding. And 2 different styles of head draining.

Engine 1 - External drain off the rear right corner down to a tube in the block placing the oil into the bottom of the pan.
Rear original drain blocked. Front original drain restricted.

Engine 2 - NO external drain. Both original drains fully open.

Both engines have restricted supply.

In discussing with engine builders, the advise I've been given is as such:
- External drain IS needed
- Original drains should be completely open - not blocked.

The engine that currently does not have an external drain also does not have a boss in the block - like the engine that does.
(Different castings). The suggestion was to tap the pan and drain it directly to the pan.

So, here are my questions.

Why can't I drain directly to the tank - into the port currently used for the vent tube? It's all gravity.

Do you use both drain styles together?
Is there a reason not to (other than the HP loss of oil onto the crank)?

[Purple Frog]

The external drain is to keep oil from falling onto the spinning crank assembly and costing some fraction of HP.

You probably could drain it to the tank. Engine builders don't do that because they then could not run the engine in on the dyno. Also an engine that drains to the tank would not easily be moved from one chassis to another.

I have seen many external drains tapped into the oil pan.

I have run many engines without the external drain. That said, I never won the Runoffs or a pro race.

If you ran an engine in both configurations, you would not enjoy the benefit of the external drain, because most oil would probably follow the internal route.

As always.... YMMV

[problemchild]

If you have an old car, and you are rebuilding your own engine, it probably becomes irrelevant, but the head drain would be configured in conjunction with the scavenging configuration and orifice size in your vent line. You want to be scavenging oil from the pan and not the tank.

[BeerBudgetRacing]

If you have an old car, and you are rebuilding your own engine, it probably becomes irrelevant, but the head drain would be configured in conjunction with the scavenging configuration and orifice size in your vent line. You want to be scavenging oil from the pan and not the tank.

I can see where that can be a possibility. Especially since a drain line from head to tank would be full.
Thinking about it I'm now thinking nothing would drain that way because of the vacuum in the head.

[Purple Frog]

Bingo.

Once the top of the head completely filled with pressurized oil, and just before it blew the valve cover off with 40 psi hot oil.... it would start pushing oil to the tank.

You figured it out.

Greg is right. The external drain is a good thing. But, if you are home-building an engine, and not using a dyno, you won't get to the point where that 1/4 HP at 7000 rpm is an issue in the big scheme of things. I'm guessing the best of us home builders don't get within 5 to 7 hp of a good pro engine builder. Just saying.

[JHerscher]

This is an interesting topic.

I have seen the external head drains on Elite and Farley engines but never on any of my Butler engines (Cricket Farm Motors), wasn’t on an Ivey I acquired about 20 years ago, and it is not on the Loynings I have as a spare. I have never run the Loynings, but the Ivey and the Butlers have always delivered plenty of power.

I have seen a head on another car that has the external drain plugged and expect that the internal drains must have been opened back up for obvious reasons.

I imagine that one’s corner exit speed is more important than that extra 1/4 (or whatever) hp as Mike speculates it might deliver.

John

[Art Smith]

given the objective of an external drain from the rear of 2-liter SOHC Pinto cylinder heads (or 1600 Pinto's) is reduced windage drag in the crankcase, it seems to me it follows that the external drain should be introduced into the dry sump pan below/behind the pan's windage management device AND that the internal drain should be plugged (I use a pressed aluminum plug with a rare earth magnet attached to the top). ditto an external scavenge line! the power improvement isn't large, but it's positive/easy to measure and inexpensive marginal power in the grand scheme of things; attention to detail and some simple plumbing!

under the same "attention to detail and some simple plumbing" heading, it's my opinion that all vent lines should include a check/flapper valve. first and foremost to enable creation of a vacuum in the crankcase consistent with the pump being used and with the secondary benefit of precluding scavenging from the dry sump tank. it costs very little power to scavenge/pump air (ie: wider scavenge rotors) and it's been my experience the measured power benefit at the flywheel has always out weighed the cost. vacuum in the crankcase is inherently a good thing both reducing windage and enabling reduction/elimination of other internal drag sources; the large vacuum pumps mounted/included on modern Pro-Stock engines hopefully serve as an adequate independent confirmation..................

Art
artesmith@earthlink.net

[Jnovak]

Careful evacuation of the crankcase with the dry sump system is worth 25 - 30 HP on a NASCAR V8. I have actually seen this on the dyno. Lots of crankcase vacuum!

I dont know what it is worth on your motor but i bet it is significant.

[jrh3]

given the objective of an external drain from the rear of 2-liter SOHC Pinto cylinder heads (or 1600 Pinto's) is reduced windage drag in the crankcase, it seems to me it follows that the external drain should be introduced into the dry sump pan below/behind the pan's windage management device AND that the internal drain should be plugged (I use a pressed aluminum plug with a rare earth magnet attached to the top). ditto an external scavenge line! the power improvement isn't large, but it's positive/easy to measure and inexpensive marginal power in the grand scheme of things; attention to detail and some simple plumbing!

under the same "attention to detail and some simple plumbing" heading, it's my opinion that all vent lines should include a check/flapper valve. first and foremost to enable creation of a vacuum in the crankcase consistent with the pump being used and with the secondary benefit of precluding scavenging from the dry sump tank. it costs very little power to scavenge/pump air (ie: wider scavenge rotors) and it's been my experience the measured power benefit at the flywheel has always out weighed the cost. vacuum in the crankcase is inherently a good thing both reducing windage and enabling reduction/elimination of other internal drag sources; the large vacuum pumps mounted/included on modern Pro-Stock engines hopefully serve as an adequate independent confirmation..................

Art
artesmith@earthlink.net

Keep the "cards and letters coming", very informative

[Art Smith]

attached picture shows one of my 2-liter SOHC Pinto heads before it was sold. the cylinder head oil drain was drilled and tapped in the rear of the head for perceived packaging advantages; a XRP Wiggins fitting was used. the drain as shown was connected to one of the dry sump pump's three scavenge rotors AND a pressure equalization -10 hose was connected from the crankcase to the valve cover. the old/obsolete rear water return design is shown; I now drill & tap just like the rear oil drain. note under the "attention to detail and simple fastening technique" heading ALL of the fasteners are either drilled for safety wire or staked; neither help horsepower but significantly improve reliability. all that's required is a drill press and patience!!

Art
artesmith@earthlink.net

[EricP]

I have two engines with both setups. One is an Elite (with outboard hose) and the other is unknown without it. Unfortunately they are both out right now so I can show both... first engine with no external drain and open holes in head. Note: on this engine the cam cover vent was LARGE ~0.50” The oil holes in the block open.

[EricP]

Notes: The two drain holes in this appear to be plugged at the block. There are earth magnets by the rear drain hole over the head bolts. Maybe a key point: the cam cover vent has a tiny hole inside what is otherwise an AN6 fitting port. An important point: I could use the Elite head on the block with no external tube (by removing tube) but I can’t use a head without an external tube on the Elite block (unless I opened the block holes).

[Steve Demeter]

Not to be a smarta.. but Eric when you finally put that car on the track it will have to be the most thoroughly analyzed and prepped CFC of all time. Nice job so far.

[EricP]

Not to be a smarta.. but Eric when you finally put that car on the track it will have to be the most thoroughly analyzed and prepped CFC of all time. Nice job so far.

Thanks, I think. I did have it on for the SVRA event but it had issues. In a lot of ways it was great but 32% leak down and oil blowing out not good...

[BeerBudgetRacing]

Notes: The two drain holes in this appear to be plugged at the block. There are earth magnets by the rear drain hole over the head bolts. Maybe a key point: the cam cover vent has a tiny hole inside what is otherwise an AN6 fitting port. An important point: I could use the Elite head on the block with no external tube (by removing tube) but I can’t use a head without an external tube on the Elite block (unless I opened the block holes).

This is exactly how one of my engines (that was claimed to be Elite) is done - although it has QS stamped on the head as well.
I did not have the restricted vent though.

The front plug also had a small hole drilled through it (maybe 1/8) but the rear was blocked and tapped like yours.
That connection at the block dumps directly to the pan, but not into the area where the scavange lines are..

[BeerBudgetRacing]

Keep the "cards and letters coming", very informative

I've got other questions I will ask as I re-build my motors. I'm going to collect it all into a document to share.

[BeerBudgetRacing]

the drain as shown was connected to one of the dry sump pump's three scavenge rotors AND a pressure equalization -10 hose was connected from the crankcase to the valve cover

Art, I think most Pintos are run with a 3 port (2 scavange and 1 pressure) pump.

Do you think the gains are worth the more expensive pump?

If we are externally draining the oil from the head, do you think making some sort of stand-pipe into the existing head drains instead of a block off plug would allow enough pressure equalization? Wouldn't that meet both objectives?

But, wouldn't the vacuum pull through the "pressure equalization" plumbing instead of the drain? Is that maybe the reason my front drain was plugged but had a small hole drilled through it? I didn't think it would drain much oil but I can see vacuum being pulled.

Just thinking out loud.

[Purple Frog]

Don't over engineer. Thats my opinion.

Use the head with the drain,
Use the three port pump.
A small hole in the front drain will work.
Total plug in the rear drain.
The two scavange pumps are enough.

Niki's engine from Elite was probably putting out 155 hp 13 years ago using that technology. Its good.

Pinto power is almost totally dependent on the head. And there are only a limited number of "special" heads out there. The engine builders know which numbers they were when they stamped them. Somebody else may have screwed it up later.
The second most important thing is cylinder bores and piston and ring clearances.

Use all the newest legal parts.
Work hard to get cylinder walls, piston clearance, rings, etc. correct.
Get the pistons to zero deck height.
Get combustion chambers to minimum.
Do a legal valve grind.
Use the correct valve springs (not too stiff)

Put it together and go racing.
As a home builder, and without a dyno, there is only so far you will get. But you can build a good 145-148 engine, if you measure everything correct. But are you going to be able to make sure the top of block and crank are parallel? That the bores are exactly 90 degrees from the crank. etc. etc. etc. Most likely not. But you can put it together and go have fun.

OBTW, I always blocked the breather port on the valve cover. Old timey tech inspectors want to see a hose to a catch tank. I had all that, but it was blocked (all but a tiny hole). If you ever need a breather, the engine is already toast.

[BeerBudgetRacing]

Thanks Mike for the reality check.

To be honest I'm not looking for the last HP. What I really want is to understand the what änd why.
And to document as best I can for later reference.

The engine I'm working on was an Elite at some point. Touched by QS at another. I confident someone else had a go at it since them considering the blunders I have found.

My goal is to build it as best I can for reliability.

[jrh3]

Maybe we could touch on oil restrictors and oriface size......

[BeerBudgetRacing]

Maybe we could touch on oil restrictors and oriface size......

On my block the 3 feeds off the main galley were tapped 3/8-16 about 1.25in deep. Do not know what the original size was.

A simple plug ( like https://www.mcmaster.com/91375a617 ) was inserted and tightened into place.

The front and rear plugs had holes in them from what appears to be a #51 (.0625) drill bit.
The middle plug was drilled with a #43 (.0881) as it feed the oiler bar.

All things considered - very small compared to the original which I assume was at least 1/4 or 5/16 in.

[Purple Frog]

Its always a good idea when cleaning the block to remove those plugs. Just saying.
Some of the measurements you have found I am adding to my "manual".

I've seen water pumps with modified vanes. Always thought an electric water pump was the ticket. But getting enough power to run it for 45 minutes poses another problem.

There are carbs, and then there are CARBS. Never thought much about the carb until i bought a pro engine one time that had a QS carb. All sorts of special little tricks inside.

[jrh3]

Its always a good idea when cleaning the block to remove those plugs. Just saying.
Some of the measurements you have found I am adding to my "manual".

I've seen water pumps with modified vanes. Always thought an electric water pump was the ticket. But getting enough power to run it for 45 minutes poses another problem.

There are carbs, and then there are CARBS. Never thought much about the carb until i bought a pro engine one time that had a QS carb. All sorts of special little tricks inside.

Any my thoughts on improved cooling and oiling for cylinder #4?
Aux water outlet on back of head?
The Holbay external pump and side inlets look like the ticket, just don't happen to have one sitting around.

[BeerBudgetRacing]

Any my thoughts on improved cooling and oiling for cylinder #4?
Aux water outlet on back of head?
The Holbay external pump and side inlets look like the ticket, just don't happen to have one sitting around.

I'll forward you some pics from Art Smith. He feeds oil for #4 through the ball plug port.

I always thought the 'heater' outlet on the pump that normally gets plugged could be routed directly to the rear freeze plug as an improvement.

[Rick Iverson]

......I have seen many external drains tapped into the oil pan....

Frog;

So if I understand correctly, the head drain points are plugged (I recall from my FF days inserting restrictor plugs). My Farley is internal, but my curiosity is piqued by the thought of draining into the pan.

Q: In plumbing to the pan, can I presume there is negative pressure to “draw” the oil?
Q: I looked at my head, and there is no port where an AN fitting can be installed for external drainage. I surmise the head must be machined, yes?

V/r

Iverson

[Art Smith]

Frog;

Q: In plumbing to the pan, can I presume there is negative pressure to “draw” the oil?
Q: I looked at my head, and there is no port where an AN fitting can be installed for external drainage. I surmise the head must be machined, yes?

V/r

Iverson

Rick-

gravity moves the oil to the pan through an external drain line/hose just like gravity moves the oil in the internal OEM design.

the cylinder head needs to be machined for both an external drain and a supplemental scavenge line. the questions are: driver's right or the rear of the cylinder head AND NPT or ORB. mounting the cylinder head securely so the surface to be machined is square to the spindle is 90% of the work..................

Art
artesmith@earthlink.net