Engine Blue Printing - 1275cc A-series - Introduction & Engine Block #1

• Surface plate, 18" x 24" (min)

• Micrometer, 2"

• Mirror, 1" x 1"

• 360° protractor

• Height stand, 18" (min)

• Micrometer, 3"

• Gauge blocks, 0" to1"

• Protractor-to-cam adapter

• Indicator, 0.0001"

• 1" to 3" ID snap gauge

• Standards, 1" to 12"

• Indicator, 1" travel, 0.001"

• Indicator. 0.0005"

• 1" to 3" ID Bore Gauge

• 1-2-3 blocks

• Flexible indicator arm

• Magnetic indicator base

• Kant twist clamps

• 12" angle plate

• Feeler gauge

• Parallels

• Leveling table or jacks

• Laptop

• Calculator

DISCUSSION:

• One of the biggest challenges in the BPing is working with the given set of tools to make all the necessary measurements.  At many points, I had to get pretty clever as you can see in some of the photos of the measurement setups.
• The spreadsheet below steps through the measurement of the engine block.
• The first thing to notice is the near stock size of the cylinders.  This means that any form of overboring can be done, even the dreaded offset boring used for the big block A-series motors.  Ok, V8 guys stop laughing.  Going from 1275cc to over 1400cc is a huge jump for a little motor like the A-series.  Just think if we had another 4 cylinders.  Then it would be even more.  HA HA HA...
• Moving to the second cylinder section titled "Tilt (inline, relative to deck)", the shape of the cylinders from their front-to-back is rather interesting.  Cylinders 1 and 2 are both of the same shape, but cylinder 2 has considerably more taper.  But then for cylinder 3, the taper reverses.  And, don't even ask me to explain cylinder 4, but then it's kinda similar to cylinder 1.  Cylinders 1 and 4 probably have something to do with the fact that have their own main caps on the crankshaft that cause similar dynamic loading on the pistons.  Whereas, cylinders 2 and 3 have only one main bearing cap to support them.  Then, you add in the flywheel/clutch loading... I have no clue about that.  I will have to think about this more or just accept it as fact and forget about it when the cylinders get overbored for more horsepower.
• On to the third section of the spreadsheet, titled "Perpendicularity to Journal"...  Everything here appears to fairly normal.  The one side wall that was measured seems to have the same tilt, except for cylinder 2 as you can see by the pink highlighted numbers.  Once I saw the results, I even went back and measured a second time...  same results give or take a few ten thousands.  The other pink section concerns the location from side-to-side of the crankshaft journal.  It appears that the crankshaft journal centerline is offset by 0.011" from the ideal centerline of the cylinders.  I'm not sure if this is a problem since this is the direction of freedom for the pistons/connecting rods.  In actuality, I bet you need to have some offset or else your top dead center of the piston would be at top dead center of the crankshaft.  My gut says this would be problematic from a dynamic stress and vibration standpoint.  Hmm, interesting question for an engine designer... maybe Vizard?
• In the section titled, "Crankshaft," not much is going on except that you notice their is a little bit of vertical tilt of the crankshaft relative to the deck... about 0.0016".  Is this a lot?  No idea.  Maybe I should take a look at bearing clearances and the tolerances involved in the crankshaft system to determine if there is enough clearance to accommodate the tilt.  I will make a not to do this.
• For the fourth section, titled "Deck," there are some interesting results.  The deck is quite flat with a 0.002" range.  But more surprising than the deck is the back surface.  It's actually rather square (0.001" tilt or 0.007 degrees) to the deck.  I believe this indicates that the back surface is the principle reference surface for manufacturing the engine block.  I go into further discussion below next to the photo which shows the setup used to measure the back surface.
• Ok, even more of surprise is the pan surface.  It's flatter than the deck.  It really doesn't have to be except around the main bearing caps, but it's nice to have when it comes to engine BPing.  The principle reason for making this a "good" surface is to establish the main cap surface and thus crankshaft journal.  Turns out the crankshaft centerline is practically right on the pan surface within the accuracy of my measurements/calculations... not bad for pre-CNC machine tools.
• The last section covers the cam journal.  This was a bit harder to measure due to the fully enclosed journal and the smaller journal sizes.  As you can see, I could not measure the center journal due to it's location.  However, it looks to be about as accurately machined as the crankshaft journal.
• The front surface was not measured since it's insignificant to the operation of the engine.  However, based on the other surfaces, I bet it's pretty accurate.
• Lastly, prior to BPing the block, I thoroughly cleaned it which wasn't much since to it's pristine condition.  It still needs a dip in a professional cleaning rig to ensure absolute cleanliness prior to re-machining.  Additionally, I replaced all the brass oil way plugs with threaded pipe plugs ala Vizard's guidance.
• Ok, one last thing to add to the discussion...  If you do not own a copy of Vizard's book, "Tuning the A-Series Engine, The Definitive Manual on Tuning for Performance and Economy," you better get off your but and buy it before attempting any tweaking of your engine.  I highly recommend it.  Vizard is Mr. A-Series... period!

SUMMARY:

• The #1 block is in fabulous shape.  It's ready for anything to be done with it, including just rebuilding it as is.  But, I have grander plans for it which include overboring, replacing the cam bearings and finding out if centerline boring of the journals is even needed... some how I doubt it.  It appears to be mostly a virgin block with only the cylinders being slightly larger than stock.  At most they received one or two hones over the years.  Let's hope there aren't any cracks... not likely, but you never know.

• Well, here's #1 in all it's grandeur prior to fully ripping it apart.  This engine is in really good shape with hardly any corrosion on the inside of the water passages.  My father said that if you could find a Ford Flathead in this good of condition, it would be worth a small fortune... just for the block.  It turns out as the BPing will show, that #1 is a far superior engine to #2.  The machinist who rebuilt it.  From my best guess, this engine was never re-machined.  At most, it received a honing of the cylinders.  Additionally, this engine does not have the inferior casting "break through" under the center main cap, unlike #2.  Thus, this engine could be turned into a significant power generator.  However, the block still needs to be Magnaflux tested for cracks.  Crossing my fingers.

• This setup is what I used for measurement of the cylinder alignment to the crankshaft journal.  The first challenge was just getting the block positioned next to the angle plate for clamping.  Then I had to figure out how to level it.  If you look at the bottom corner closest to the front, you will see a little jacking screw that provided the necessary fine control to level the block horizontally to the surface plate.
• The nest challenge was figuring out the complex geometry needed to account for the way I was measuring the journal location.  I had to account for the offset of the indicator tip from the surface plate and the theoretical center of the crankshaft journal.  If you take a look at Sheet #1, Cells D21 and F21 on the spreadsheet, you will see the equation generated from the geometric analysis.  The values are not huge, but they are rather significant if you compare them to the numbers from other measurements of this engine block.
• Funny.  Even with the weight of 75+ lbs for the angle plate, the block mounted on it was pretty close to wanting to tip.  Well, two drill press vises and box full of brass later, problem solved.

• This is the setup I used for measuring the cylinder shape.  It is represented near the top of the spreadsheet by tilted lines.  You can actually see one of the cylinders has a pretty gnarly shape in comparison to the other.  It's highlighted in pink.  I even remembered in the calculations to account for the indicator tilt.  

• The significance of this photo is the leveling table that the block sits on.  I was fortunate that my father had this table and...  our A-series engine blocks just barely fit on it.  Leveling capabilities are absolutely necessary for BPing.
• Leveling any surface was achieved by picking three datum targets that were zeroed.  Then the rest of the surface was examined for flatness or other surfaces were measured using the deck as the reference.  At a later date, I plan to scan the original data sheets that I used to track data like this.

• Ok, ignore the #2 marked on the engine.  This is really engine #1.  I discovered my mistake part way through the BPing.  Using machining parallels, I was able to measure the parallelism of the deck to the pan surface.  Pretty simple, eh?

• In this photo I am checking the perpendicularity of the back surface of the block to the deck.  If you take a look at the results in the spreadsheet above, you will see that the average angular difference from perfectly perpendicular is 0.007 degrees or 0.001" over the height of the block.  This measurement was taken with the deck leveled to the surface plate.  I think we may have found the principal reference surface for at least this generation of A-Series engines.  However, the BPing the second block will help to confirm this.  But, a warning must be given about this reference surface.  I do not know if there were multiple engine block sources for the 1275.  During this period in the automotive world, it was pretty common for automotive parts to be sourced from either multiple vendors or moved from one vendor to another frequently.  What this means is that different sources could start from different reference surfaces.

• This photo shows the dial bore gauge that I used to measure the various bores.  On all the small bores, I could use the stock parts that came with the gauge.  But, for the cylinders, I had to make an adapter to increase the gauge's capacity.  Basically, all I did was turn two pieces of brass on my lathe to make adapter pieces.  The first piece with the set screws adapts the off-the-shelf adjustment screw (1/4-80 thread) to an intermediate piece that allows for the connection to the gauge.  With two different adjustment screws (short and long), this gauge now can measure V8 sized cylinders.  Wondering what the springs are for?  They preload the adjustment screw while measuring since there is still a very slight gap in order to let the adjustment screw move... but the gap is on the order of 1 or 2 ten thousandths of an inch.
• Ah, something of importance using a bore gauge like this.  It helps to have measurement standards or gauge blocks.  My father has a complete set of gauge blocks that allow for standards beyond 12" to be established.  I used the gauge blocks frequently to calibrate the measurement equipment and ensure accurate readings.

• Ah, checking the angle plate's accuracy.  It turns out this Chinese-made angle plate that was sold as damaged goods for cheap is really quite accurate.  All that needed to be done is take a file to the corner where someone dropped it onto the concrete.  Wham!  Suddenly, we have a 12" angle plate that's 0.008 degrees past a perfect 90!  Or, it has a tilt of 0.0016" from bottom to top.  This turned out to be a pretty good find for my father... and one that was only $25 if memory serves me well.

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