[ CLOSE ]VACUUM: Checkin' Out a Lot of Nothin'
That’s what a vacuum is...a lot of nothing. Your engine is a pump and what it does best is create a vacuum. If it didn’t it couldn’t run. It could not “draw” in a fuel charge to make the combustion chamber power against the pistons. A vacuum is absence of air, but it is not exact or 100 percent effective. It never is.
When your engine is running it is constantly creating a vacuum by the downward motion of each piston. The vacuum is measured in inches. Inches? Yes. Many times the measurement is stated in pounds, but the term is incorrect. The original method of measuring vacuum consisted of a “U” shaped tube-containing mercury. (This is not your father’s Mercury.) This lab vacuum tube was marked in inches to measure how far the column of mercury would rise.
Fortunately we don’t use the mercury column for our Mercurys (pun) in the shop. The dial indicator vacuum gauge with a hose is what we use. It translates the mercury tube reading to a pointer on a round scale. It is easy to say pounds instead of inches when looking at the pointer on the 0-30 inch dial. Technically, 30 inches cannot be attained, but maybe 28 or 29 can.
Vacuum gauges used for engine tune-up or troubleshooting are not common today as they were years ago...like in the flathead V-8 era! I remember them in Auto Shop. They still can be used and the readings can be helpful when looking for engine problems. So, a normal running engine will have a vacuum reading on the gauge of about 17-21 inches.
If an engine has poor piston rings (cannot create a good vacuum), then the gauge would read a few numbers lower. When the gauge reads extremely low, it could be an indication of an air leak at the intake manifold, carburetor base or anywhere. A rapid deflection of the pointer up and down in time would reveal a burnt or sticking valve. A slowly declining pointer towards zero may show a restricted exhaust. Being that the engine is a vacuum pump, the readings on the gauge reflect what the engine is doing. T
The gauge, though, doesn’t tell all; further testing must be done. Additional tests include checking the cylinder compression; air leakage test that shows where compression is escaping, like piston rings, head gaskets or valves; ignition and camshaft timing should be checked. Tune-up specs must be correct for the best vacuum reading.
What is a vacuum? Remember your science class? Well, it’s a whole lot of nothin’! It is absence of air. When an engine piston moves down on the intake stroke it is displacing air, creating a vacuum. Air, being a big bully, rushes in to fill the void and the only place it can find to enter is at the carburetor. The air joins with the fuel and the air/fuel mix is pushed into the cylinder. Air is not sucked into the engine...and it is not drawn or pulled into it, either. It is pushed in! 14.7 pounds of atmospheric pressure at sea level makes the air rush in. Yes, pounds this time, to inches! How do pounds become inches? I don’t know. Ask Albert.
Now, next time you do a tune-up on your engine be sure to check nothing. Something can be a problem, but a lot of nothing is not. Your engine creates nothing; be sure it does so efficiently. You can read Don Cunningham’s Tech Tips in The V8 Times
Related Documents: Vacuum Gauge Readings
[ VIEW ]V-8 Engine: Eight is Enough
By Don Cunningham (from Big Valley Rumble newsletter)
There are commonly four, six and eight cylinder engines. At one time, old Henry thought four cylinders was all that a car needed. Of course, he changed his thinking about that idea with the introduction of the '32 Ford.
The in-line eight cylinder engine of the past was quite popular. Even before Ford came out with the V-8, the in-line was a common power plant. It was very smooth and quiet but heavy and long in dimension, having pistons all in a row.
The six cylinder engine was very common, also, and you-know-who made it one of the most famous engines of the time. Henry would not build one because you-know-who alread was building the six. The six-cylinder is a very efficient and cool running engine. It wasn't strong on power but it was reliable.
Engineers of the past had explained several advantages of the V-8 engines over the in-line engines: the engine is shorter, lighter per cubic inch and of more rigid construction. The "V" design uses a more compact fuel distribution in its intake manifold, so the air - fuel mixture is delivered more evenly. A straight-eight engine was known for fuel starving at the end cylinders. A stronger crackshaft is a feature in the V-8 engine because it is shorter and not susceptible to twisting like the longer shaft in the in-line engine. The V-8 design allows more passenger space, too, and a shorte4r wheelbase could be used.
Well, of course, the V-8 engine has proved itself over the years and decades and Henry is given most of the credit for the engine's success. He made the V-8 available cheaply to the masses (most V-8 engines of the 30's were expensive to build). Not until 1955 did you-know-who build a V-8 engine for their cars. But by then Ford had a six cylinder engine, too . . . so
A six cylinder, along with a V-12 engine, is an inherently balanced engine; it means "the arrangement of the crank throws are in the same radial plane, making it a perfect blance of both primary and secondary inertia forces." The V-8 is not inherently balanced. Still, the V-8 because the most popular engine in use. Happy V-8ing. [Don Cunningham's Tech Facts, from July/August 2002 V-8 TIMES]
[ VIEW ]The V in V8
The "V" in V-8 really does not stand for anything, other than a description of the shape of a gasoline/diesel engine. When you look at the front of a V-8 engine, what you are really looking at is a "V" configuration. (The crankshaft at the bottom center with pistons in the upper right/left of center.)
If you draw an imaginary line from the crankshaft to each piston, you would have a "V" shape. This could also be as a V-4 (Briggs & Stratton engine), V-10 (in the modern Ford engine), a V-12 (1930's through 1948 Lincoln), or even a V-16 (as in World War II Rolls-Royce aircraft engine).
They are all "V" shaped engines, with a different amount of cylinders. Now you know.
[ VIEW ]The Master (Cylinder) Rules
Jim and George were going on a camping trip for five days, but Jim’s ‘41 Ford Sedan had a problem. “The master cylinder is leaking, George. There was brake fluid all over the driveway this morning.” The guys were driving the Ford to Lake H2O and hiking from camp there. “My friend is a mechanic and maybe I can get him over here to help us repair the master cylinder. I’ll call him,” said George. In no time at all Carl was there and looking at the 12 year old car. “Jim, this car probably has never had the master cylinder off. It is leaking, all right.”
After removing the cylinder assembly and taking it apart on the workbench in the garage, Jim was fascinated by what Carl was doing. “Carl, do you know where all those parts go?”
“Sure,” Carl responded, “I’ll tell you about them....”
“Pressing on the brake pedal forces the pushrod against the piston. The piston has a primary seal cup in front of it and this pushes the brake fluid. A secondary cup is installed onto the piston and it holds brake fluid within the piston. Look at this picture in the manual; the primary cup is just covering the compensating port when pressure is applied to the brake system. When the brake pedal is released, fluid returns to the reservoir via the now uncovered compensating port. The spring pushes back the piston. But, while the brake pedal is released quickly, fluid enters from behind the primary cup into the area that before was pressurized brake fluid.” (At the return spring area.)
“Do you see now...the fluid goes past the primary cup to make up for the yet returning brake fluid in the brake lines. When the fluid does return, it goes into the reservoir by way of the small hole, which is the compensating port. There is high fluid pressure on and off at the area where the spring is, but there is never high pressure behind the primary cup.”
“George, do you know what Carl is talking about? It seems the brake fluid is going wishy-washy, moving both ways.” George was listening, too, all this time and spoke what he knew from what Carl was saying. “Look, Jim, the brake fluid is pushed into pressure by the pushrod pushing on the piston. The piston has the primary seal cup and it builds pressure into the brake lines and then to the wheel cylinders, applying the brake shoes. There can be no pressure of fluid until the primary cup passes the compensating port. When the brake pedal is released, fluid returns to the reservoir by way of the uncovered port. The replenishing port (second hole) refills the area between the cups, the fluid going back and forth at the primary cup.”
“How come you know so much, George?” said Jim. “Huh? Well, I was listening and paying attention. What were you doing while Carl was explaining the brake operation?” “Oh, well, I was thinking about Henry Ford’s mechanical brakes on my ‘36. They aren’t the same, are they?” Um-m, no. So, Carl installed a new kit and bled the brakes. They worked fine. What a break! ...brake? No,...break.
Please see more of Don Cunningham’s articles in the V8 Times.
[ VIEW ]On Higher (Resistance) Ground
The ground side of the battery and electrical system-does anybody think of the ground circuit and return of the electrical path from the battery? Most of us, when working with the battery and electrical system, think only of the "hot" side of the circuit. For every electric component on the car there is a sometimes forgotten ground side while the current flows from the battery.
One of the first troublesome things that we V-8 people think of is the cranking motor, or starter, as commonly named. With the original 6-volt electrical system, there seems to be much trouble cranking over the engine. How come in the old days the starters did just fine?
Well, everything then was new; starter motor, cables, battery and yes, the ground system. There was no resistance at the ground side of the battery when the car was new. What did we do to cause resistance to creep in? Look where the ground circuit has to go on our flathead-it travels from the battery to the body cowl via a ground strap, then from the cowl to the engine (a bolt somewhere) through another ground strap, then through the OIL PAN before the ground gets to the starter.
When we rebuild or overhaul the engine, some (oh, dear!) resistance can enter the body and can get rusty (resistance), the old cables do not pass current like they used to (resistance), the engine bolts-threads may not be clean (resistance) and finally the engine oil pan does not pass the ground circuit easily because we have painted everything. The problem is not 6-volts, but the lack of it. A 6-volt system will work well as intended if it is maintained properly.
So, let's install new proper size battery cables (at least #2, factory made) from a correct battery onto clean surfaces with clean bolts. Remember that 6-volts requires larger cables or straps than 12-volts. Then let's clean off all the paint where there is metal-to-metal contact for good ground circuit flow; that would be at the cowl, engine and bolt, oil pan bolts to engine block and starter mounting flange on the oil pan.
Don't forget the starter motor itself-it must be shiny clean where it contacts the oil pan. An improvement right here is to install an additional ground strap (a braided one) from the battery cable where it fastens to the body directly to the starter motor attaching bolt. This will "send" an almost direct ground from battery to starter.
Remember, too, the starter relay ('37 and later) and its connections must be resistance free. A voltmeter check at any point in the electrical system must show no appreciable voltage drop. Connect the voltmeter across (parallel) any circuit in operation and there should be no resistance (drop). You will be surprised how much all this can add up; a few tenths of a volt drop here and a few tenths there will total up quickly on our 6-volt system.
Finally, DO remember the starter motor itself! It must be binding-free, have new brushes, well-oiled new bushings and correct amperage draw through the field windings. Don't let a tight engine fool you, either. No starter, 6-volt or 12-volt, will operate as intended when the engine is too tight, for whatever reason. Use a volts-amp tester and ohmmeter such as Sun makes to test everything. The instruments are not hard to learn. Get all this together and the 6-volt system will work well.
And for gosh sakes, don't install an 8-volt battery! You are inviting trouble with a higher charging rate, excess heat and burned out lights. Service the six. The six will serve you. Don Cunningham Ceres, California Don't Miss Don's Tech Facts in the V-8 Times
[ VIEW ]How to Aim Your Headlights
Dick Flynn's Tech Tips July/August 2011 V-8 TIMES magazine
It is very important that your headlights be aimed correctly so you don't blind oncoming traffic. Also so you can see the road in front of you.
Correctly aimed headlights light up to about 350-feet of the road ahead on low beam, but if they are tipped one-half degree lower, visibility is cut to about 250-feet. High beams nearly double the low beam seeing distance.
Keeping headlights properly aimed is no real problem. You need 35-40 feet of flat or constantly sloped driveway in front of garage doors:
1. Shine the low beams on the garage door from two- to three-feet away.
2. Outline thr bright spots on the door with tape.
3. Back the car to about 25-feet from the garage door. The top of the low beams should shine no higher than the top of the marks on the door or lower than the center of the marked circle.
4. You can adjust so this works out by moving the adjusting screws.
If you have only two headlights on your car the high beams are automatically aimed when you aim the low beams.
If your car has four headlights, aim the low beams first. They are the outer or upper two lights. Then adjust the high beams until the center of the high beam is at the top of the low beam.
To check the sideways aim, sight thru the center of your rear window at 25-feet. If your lights are cross-eyed or wall-eyed, adjust until the beams appeasr straight ahead and distance between them matches the distance between the headlights.
This is just a rough way to check without headlight adjusters, but will come out very close and will give you an idea how your lights are and where they're pointing.
[ VIEW ]BATTERY CABLE CLAMPS
Dick Flynn's Tech Tips (V-8 TIMES magazine Mar/Apr 2011)
When I go to any car function where the hoods are open to show the engine, I always am curious as to the quality of the workmanship. I always look for unsafe parts.
I have seen too many V-8 failures due to poor kknowledge that the car owner has. One of the most unsafe and trouble causing parts are the cheap fix clamp-on battery cable clamps. I se too many home repaired that have the clamp-on cable clamps. They are very unsafe as they can fail while running down the freeway. There are too many serious accidents caused by simple mechanical breakdowns.
These cheap fix battery clamp-on cable clamps don't make a 100% electrical connection where they clamp on to the cable strands and in time, they get worse as corrosion sets in. CABLE CLAMPS NEED TO BE SOLDER SWEATED OR FACTORY CRIMPED TO BE SAFE !
I also see corrosion caused by storage batteries that have had too much water added to the cells. Most all the new 6- and 12-volt batteries have large fluid compartments. With the newer battery materials, the batteries create less heat when being charged in regular usage. This in turn helps the water in the electrolyte evaporate very slowly.
I suggest to only fill the fluid compartments one-half full only! This way as the battery charges and is shaken by rough roads, the acid won't splash up on the filler caps and leak out into the battery box.
One more safety suggestion. If you ever have a fire in your car (any car), the first thing you need to do is disconnect the grounded battery cable. Until the battery is disconnected, the fire in most cases can't be put out for as the wires melt, they short out and make more fire. I keep my cable clamp bolts in perfect shape to be removed easily. I carry a wrench in the glove box of my modern cars. On my collector car, I have installed a battery shut off switch. All I need to do to disconnect the battery is to twist out a plastic handled stud. This switch is installed in the ground calbe only!
Two more needs for a fast battery disconnect:
1. If your starter solenoid happens to stick and keeps the starter engaged after you release the start switch.
2. If the engine happens to start with the starter engaged with the solenoid stuck feeding electricity to the starter. The starter could explode if the engine spins it too fast.
I always hear people saying to take the battery filler caps off the battery when trickle charging. They say this keeps the battery from blowing up!
Here is another one of my "think about it common sense subjects," Do you take the battery caps off when the generator is charging the battery and could be charging up to 30 amps? When you remove the caps on a charging battery, you make a larger area of hydrogen gas therefore a larger chance of explosion.
Do not torque the batytery post loose in the battery case when you tighten the battery clamp. It should only take very little torque on the clamp bolt nut to make the clamp tight. Any questions, contact Dick Flynn.
[ VIEW ]Back In the Saddle Again
BACK IN THE SADDLE AGAIN That title was Gene Autry’s cowboy song. Here, the title we are discussing is the saddle in the main bearing and connecting rod supports; where the caps bolt down to hold the bearings in place.
Rod bearings and main bearings do a great, tough job of supporting/transferring reciprocating motion into rotating motion. With all the miles and RPM’s our old Fords engines run, it is amazing how the bearings hold up.
One of the problems that the old flathead engines have is low oil pressure (you knew that). When an engine is rebuilt the saddles of the main bearings and the saddles of the con rod must be true in size and concentricity. The main bearing saddles probably are fairly true after many miles and years of operation, but the rods may not be true in bore and alignment. Rods really take on a tough job, the top end reciprocating, the bottom end revolving and all the while under the pressure of the driving piston.
Low oil pressure, then, can be caused by the con rod crankshaft end being out of round or elongated. There is too much clearance for oil pressure to build up. Machining the rod parting ends a few thousandths and then truing the bore back to the original measurement is the way to go. Also, aligning the rod for possible twist or bend should be done. Your favorite, experienced machinist can do this. Of course, all other measurements should be checked out and corrected including the camshaft bearings and the cylinder bore, etc. The point here is that so many times the engines can be “rebuilt” and critical sizes and measurements are not checked over. “Just ring and valve it, Lou.”
A note here about the comparison of our old Ford, Lincoln and Mercury engines to the late model car engines. You know the ones...Toyotas, Hondas and Nissan engines, the ones that are foreign to Fords. Well, the flathead con rods CAN be in fairly good shape when disassembled as compared to the high revving, high heat, high stress engines of the T, H and N engines. These engines are built to very, very close tolerances and must stay that way for efficiency and low emission. But, they can have troubles in worn con rod areas and, oh boy, yes, in the aluminum cylinder heads!
The flathead engines don’t work as hard or run as hot as the new cars. Is that a correct statement? OK, they both work hard and run hot, but in a different way. The flathead engines don’t have the same stress as the modern engines and the cooling system holds 22 quarts of coolant opposed to the SEVEN capacity of some new cars! So, check the saddle and all other components for a good rebuild. Gene Autry did. He checks his saddle each time he rides.
Did you know the rod bearings are installed differently on early Ford, Chevrolet and Plymouth engines? Ford V-8 has free-floating bearings; Chevrolet OHV Six features poured babbit directly onto the rods and Plymouth Flathead Six uses precision inserts that snap into place. Yes, all three car makes which are so different and yet so popular.
