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Cylinder Head Cross Section (click to enlarge)

Cylinder Head Cross Section (click to enlarge)

Cylinder heads are the gateways to and from the combustion chambers formed by the pistons in the cylinders.  As the crankshaft turns, cycling the pistons up and down in the cylinders, it also rotates the camshaft, which in turn synchronizes the opening and closing of the valves, 2 valves per combustion chamber. One valve opens the passage for fuel to enter the combustion chamber. The second valve opens to allow waste gasses (exhaust) to exit the chamber.  The valve seats(shown red in the diagram) are the areas where the valves contact the head to close the passage.

The valves cycle open-and-close in a “4-stroke” combustion sequence, as shown in this animation. 4StrokeEngine_Ortho_3D_Small

  1.  The first valve opens to allow the fuel aerosol coming from the carburetor into the combustion chamber.  Then it closes.
  2.  The piston comes up, compressing the fuel aerosol.
  3. The spark plug ignites the fuel causing it to explode, forcing the piston back down.
  4. Now the second valve opens up a path to the exhaust pipe.   As the piston comes back up, it pushes the exhaust gases out.  The second valve closes.

The cycle keeps repeating (until you turn off the engine). 

The stock 1966 cylinder heads for the T-bird are made of iron. The valves are made of steel.  One of the reasons that tetraethyl lead was added to gasoline back then was that it lubricated the valve seats to keep them from wearing out too quickly. 

Since leaded gas is no longer available, running the engine with the old heads would require that a lead-like additive be mixed with the unleaded gas at each fill-up.  (EPA probably doesn’t even allow that anymore.)   So, in order to run on unleaded gas the old heads must be retrofitted with valves made of stainless steel and the valve seats coated in a modern alloy such as stellite.  But since that’s expensive, for just a few dollars more (and less logistics) an even better solution is to just replace the heads with modern aluminum heads, which are designed to run on unleaded.  And there are other advantages to aluminum heads.

Aluminum heads weigh significantly less than iron heads.  Less weight means better gas mileage. 

Aluminum conducts more heat than iron – four times more.  Temperature control is the function of the cooling system, which uses a thermostat to regulate coolant to flow through the engine, keeping it at a near-constant temperature.  For iron cylinder heads the thermostat is set to operate at about 180°F.  Above 180°F, the thermostat allows coolant to flow through the engine, cooling it down; below 180°F the thermostat closes, keeping the engine from becoming too cool. 

Aluminum heads assist in conducting excess heat away from the engine block, preventing runaway temperature increases beyond the capacity of the cooling system to handle, making it feasible to run the engine at a higher temperature.  Therefore, a thermostat set to operate at 195°F can be used.  The improved conductive efficiency of the aluminum heads transports heat away from the block allowing for the engine to be run at the higher temperature. The higher engine temperature increases the fuel aerosol pressure in the combustion chamber. The increased chamber pressure results in a more complete fuel burn.  This, in turn, creates:

  •   More power
  •   Better gas mileage
  • Reduced exhaust emissions

For those of you in the market for a fast classic, here’s a Ford Cobra Torino concept car in mint condition, built for speed. 

1970 Ford Cobra Torino Concept car

1970 Ford Cobra Torino Concept car

And it’s yours for a mere $550,000.  Click this link for more views of the car.   

First, the progress.  Some of the hydraulic lifters were rusty, and all were generally sticky.  A few of the lifters wouldn’t come apart through normal means.  I discovered that by heating the lifter body with a plumbing torch, the oil inside would expand, popping the lifter piston free (actually launching them into low earth orbit: Houston, we are Go!).  After getting them all apart, I cleaned them, tested them for smooth operation, and installed them in the block. 

Hydraulic Lifters before and after

Hydraulic Lifters before and after

The other messy job was cleaning the rocker arm assemblies.  The bar supporting the rockers is actually a hollow tube that transports oil to the rockers.  The plugs in each end had to be removed and the gunk inside cleaned out.  

Meanwhile Scott, at Mr. Transmission  (Decatur, GA; 404-921-0028),  completed the overhaul of the C6 automatic transmission.  Scott and his crew deserve kudos for their expertise and interest in the restoration project. Generally transmission shops have a bad reputation, but Scott has always been honest, clearly explains problems and options, and charges a reasonable amount for repairs.  He also offered to delay the start of the warranty period from the time the C6 is actually installed in the car and included free operational check and adjustment of the C6 once the car is drivable.  If you need transmission maintenance or repair, I highly recommend him.   

The new Edelbrock aluminum cylinder heads had been bolted on (see previous post).  The next step was to install the Edelbrock aluminum intake manifold.  It was at this point that the project was beset by a plague of delays.  

I was unable to torque the bolts securing the intake manifold to the heads.  The two rear bolts wouldn’t “bite.”  That is, the bolts just rotated without tightening further (and that “bites” a bear’s butt!).  When I removed the bolts there were pieces of aluminum thread from the cylinder head on the bolt thread.  That shouldn’t happen at the low torque applied (25 ft/lb).  I had to remove the intake to inspect the bolt holes, which damaged the gaskets, which had to be replaced. (Edelbrock, are you listening?) 

I called Edelbrock tech support and they suggested I use the Edelbrock bolt set. So I purchased a set: in fact there is no difference between the length or thread of the Edelbrock bolts and the bolts I was using.  I grant that the Edelbrock bolts are prettier.  After three more calls to tech support, they agreed to send me a few heli-coil inserts to repair the bolt holes in the head. As well as a customer satisfaction issue, I fault Edelbrock for not showing an acute investigative interest in what may be a quality control problem in their manufacturing process.

Given the circumstances, I reckoned it prudent, long term, to insert heli-coils in all ten bolt hole locations.  No doubt this jeopardizes the warranty, but what other reasonable option?  With trepidation and much angst, I carefully drilled into my $1600 set of Edelbrock heads and tapped the threads for the inserts.  As it turned out, the retrofit was successful and the heads and intake manifold will shortly be reassembled onto the block.

The aforementioned process occurred over a period of several weeks, so in the interims I began rebuilding the 4-barrel Holley carburetor.  The carb is one of the most complicated devices on the car.  It operates on principles of pressure differential, Bernoulli’s law, and the Venturi effect. Complexity withstanding, overhauling the carb is simply a matter of taking it apart, cleaning out the carbon build-ups, using the air compressor to blow out all the fuel/air/vacuum passages, and re-assembling it with new parts and gaskets.  

I ordered the rebuild kit from Daytona Parts.  By mistake, the first kit that they sent was for a 2-barrel carb.  The Daytona folks were very kind, and sent me the correct kit plus a paid return envelope to send back the 2-barrel kit.  However, near the end of the rebuild I discovered that one of the gaskets in the new kit was the wrong size.  Knowing this would be difficult to explain over the phone, I scanned the gasket image into my CAD software, added dimensions showing the discrepancy, and emailed it to Daytona.  They concurred with my observation – turns out they’d sent a variant version of my 4-barrel kit.  Again, they were very apologetic and express shipped a new, correct kit.  Happily, despite the minor delays, none of these iterations cost a dime more than the original price.  

Remaining tasks of  the engine reassembly are:

  • insert lifter rods
  • attach timing chain cover and harmonic balancer
  • bolt on water pump
  • insert distributor assembly
  • bolt on exhaust manifolds
  • flywheel
  • mate engine with C6 transmission

To prevent possible damage to carburetor, alternator, power steering pump, and fan, they’ll be attached after engine installation.   In parallel to engine reassembly, the car itself has been worked on in preparation for receiving the engine.  The engine bay was rewired; the dashboard and associated engine controls have to be renovated and reinstalled; cooling system readied; the exhaust system is being worked on; brake system overhauled; etc.

So stay tuned — the fun just never ends!

 

 

 

 

At this point the crankshaft has been rebalanced and installed.  A detailed explanation of the balancing technology will be posted soon-ish.

Pictures and drawings of parts of the car may leave the audience wanting to see what the finished product would look like.  So I searched the internet and found a photo of a similar T-bird in the colors this project envisions.

1966_Tbird_Landau

songs

Click to enlarge

Naturally the finished car will have <!–more–>a kick-butt stereo system.  To that end I created a car-themed playlist of music that I have in my library.  The selections are mostly ’80s-’90s and predominantly rhythms that could be considered a hazardous factor in excessive speed, conducive to making the acquaintance of the highway constabulary.   A proper list should also  include The Little Old Lady From Pasadena and other car songs by Jan & Dean, the Beach Boys’ 409.  et al.  Using the Comments form, feel free to suggest your own fave paeans to the Cult of the Dinosaur Burners and/or hymns to the Holy Order of the Sweet Chariot.

After installing the crankshaft, the pistons were assembled with connecting rods and rings.  The rings are circular bands of metal with a diameter slightly larger than the piston. There is a gap in the ring that allows the ring to be squeezed into the cylinder, and the ring is ‘springy’ so that it always presses tightly against the cylinder wall.  Each piston has three levels of rings: two compression rings and a set of oil rings.  The purpose of the rings is to seal the compression chamber made by the piston within the cylinder so that a) no combustion gases leak downward out of the compression chamber and b) no oil leaks upward into the compression chamber.

ring-gaps

Ford ring gap illustration. (Click to enlarge)

PistonRingGaps

Piston rings as installed. (Click to enlarge)

Yet even when compressed there is still a tiny gap in each ring through which leakage can occur.  Therefore the  ring gaps are staggered around the piston to minimize leakage.   The Ford manual illustration showing gap positioning was cryptic, so I researched the topic on the web.  There is much disagreement on car club web sites as to correct orientation of the rings gaps. What everyone agreed on is that the gaps in the rings should not line up vertically on the piston, allowing a direct path for leakage.  The disagreement is about where on the piston the gaps should be positioned.   After indecision and consideration of the competing advice, the Ford manual suddenly made sense.

block-pistons-head

Engine block showing installed pistons and left side Edelbrock aluminum head. (Click to enlarge.)

Having sorted that out, the pistons are now installed.  The new Edelbrock aluminum cylinder heads arrived and have been bolted on.

I’d rebuilt only one engine prior to this project.  It was a straight 6-cylinder for a 1958 Ford step-side pick-up.  The truck was purchased circa 1985 for my direct mail advertising venture, used for hauling mail to the main post office.  There was often so much mail that the front wheels were in danger of lifting off the road, which when added to the excessive steering wheel play made for hair-raising trips.  It also burned more oil than gas — I kept gallon milk jugs of used motor oil on board (free from service stations) to sate its daily appetite.

Stepside Clyde, the Wonder Ride

Stepside Clyde, the Wonder Ride

At the time, I lived on a rural six acre plot with 2 chicken houses, hog house, barn.  I extracted the engine with a come-along hooked to the rafters of a chicken house.  The rebuild was very basic and low tech. Didn’t re-bore the cylinders and the original pistons were re-used.  Only the rings, standard bearings, and gaskets were replaced.  Reassembled in the truck, I was shocked when it actually started and ran (didn’t expect it to).

The truck was rather ugly, but that was its distinction.  I named ‘him’  Stepside Clyde and we stuck together through many a woman.  Even though I had a new Jeep, the truck was fun to drive and I kept it for several years.

Exploded view of crankshaft-to-engine block assembly.  Engine block is inverted, as it would appear mounted on its work stand (removed from the car).

Exploded view of crankshaft-to-engine block assembly. Engine block is inverted, as it would appear mounted on its work stand (removed from the car). (Click to Enlarge)

Ah…but we digress.

As Jeff Foxworthy reminds us, if you’ve ever had to move an engine so your wife could take a bath, you might be a redneck. So, after swearing on a stack of Cosmopolitan magazines that reassembling the T-bird’s 390 was a clean endeavor that need not preclude feminine ablutions,  I received the blessing of  She Who Must Be Obeyed to bring the engine block onto our sun porch, all warm and dry.

After sliding the camshaft into position, the next step is to install the main and connecting rod bearings.  Each set of bearings should be measured for clearance (or gap) between the bearings and the crankshaft.  This clearance should be just enough to allow the crankshaft to rotate within a circular cushion of oil, without touching the bearings. (See cross section diagram below.) Too narrow a gap risks metal-to-metal contact, which can lead to 1) burnt bearings,  or 2) actually causing the bearings to be ‘spun’ out of their seats.  Too wide a gap risks a drop in the oil pressure needed to sustain the cushioning effect.

bearing-Xsection

Cross section showing crankshaft rotating inside bearings on layer of oil. (Not to scale)(Click to Enlarge)

 The easiest method for measuring bearing clearances is to use a thin string of wax called a Plastigage. After bearing halves have been installed in the engine, the crankshaft is positioned onto the bearings. A piece of Plastigage is placed on the crankshaft journal and then the matching bearing half (installed in its cap) is bolted on top and torqued to specification.  Now when the cap is removed the wax string will have been squashed flat.  Clearance is determined by measuring the width of the flattened Plastigage using the paper reference provided.   The wider the Plastigage is flattened, the narrower the gap.

Flattened Plastigage strip after top bearing cap removed. The paper measuring tool is part of the Plastigage packaging.

Flattened Plastigage strip after top bearing cap removed. The paper measuring tool is part of the Plastigage packaging.(Click to Enlarge)

These are the results of my main bearing measurements (in inches, front to back order).

  1. .002 to .003
  2. .003
  3. .0015 to .002
  4. .002
  5. .002 to .003

The Ford manual specifies that clearances should be between .0005 and .0025 inches. However, even though a few of the above results are at or above tolerance, the expert consensus is that these clearances are acceptable, even preferred.  Also acceptable were the 8 connecting-rod bearing gaps, each measuring about .001 inches.  The next step is to have the crankshaft rebalanced, which will be the topic of the next post.

I can be an incredible cheapskate, proud of the ability to stretch a dollar until it screams for mercy.  No doubt this hubris is connected to that streak of independent self-reliance bred into the American psyche — we all want to be Henry Fords. So all too often, at least in my case, make-or-buy and DIY-or-outsource decisions tend toward over-optimistic weighting of the make/DIY side of the equation, sometimes resulting in wasted effort and increased costs. 

Case in point. After acquiring the T-bird, it stayed parked on our street for several weeks while I tried to figure out how to get a 4400 pound car up a steep driveway, 100+ feet at a 10° incline.  We tried towing it up with the minivan — not enough power.   Next we purchased a 5000 lb. winch and mounted it to the seat supports in the minivan, with the cable coming out the opened rear gate.   The plan was to pull the T-bird up 20 feet, chock it, move the van up the driveway, pull the T-bird up another 20 feet, etc.  Although tedious, that was working out fine.   Until…

Mere inches from a tragic outcome

Mere inches from a tragic outcome

In order to reposition the van the winch cable needed to be released.  This time though, the T-bird jumped its chocks and proceeded to roll down the driveway.  In desperation, I futilely grabbed the cable and hung on.  At the end of the spool the escaping T-bird yanked the cable off the winch.  Still hanging on, the car pulled me across the street onto the neighbor’s immaculate lawn, crashed through his azaleas, and came to rest one excruciating inch short of his house.  In shock, I fell to my knees and pounded the ground in humiliation and frustration. 

Thankfully, the neighbor was not at home, thereby avoiding the inevitable drama, potentially complicated by police involvement.  I called for a tow truck and after several hours work (and one snapped tow cable) we were able to drag the T-bird free and up the driveway. I left the neighbor a note claiming responsibility for the landscape damage and humbly promising to pay whatever it cost to repair.  Surprisingly, he reacted with amused aplomb and forgiveness. God bless him.  

swaybar2Fast forward a few months.  After removing the engine from the car I noticed that the front stabilizer bar (sway bar) was not straight.  It appeared to have been bent after crashing through the neighbor’s azaleas.  A local suspension shop tried to bend it back without breaking it but the result was not satisfactory.  In order to bend the bar properly it needed to be heated to a malleable temperature.  Blacksmiths have forges, and I found one willing to process the bar.  The meticulous blacksmith asked if I had a mechanical drawing for the bar.

Now, I had assumed the bar to be bilaterally symmetrical, so correcting it should have been a matter of making the right side a mirror image of the left side. A small inaccuracy could be adjusted out during front end alignment.

But no, I didn’t have a mechanical drawing.  More research.   

Readers who have served in the military need not be reminded how an angry sergeant would parse the word assume (as in: ass, [yo]u, me).  Here is a drawing of the underside of the T-bird showing the sway bar:

swaybar3

As you can see, it’s not symmetrical at all, the right side curves around the engine oil pan.  The question is, did I ask the suspension shop to distort a perfectly good sway bar?   And, without a detailed drawing, how can it possibly be corrected?   Luckily, I was able to purchase a salvaged sway bar on eBay.  Here is the salvaged bar in comparison to the original.     

new-swaybar

In summary…

1 T-bird (factor in 1 knucklehead) =  $(winch+tow truck+landscaping+suspension shop+new bar)

Cheers, y’all!

Picked up the re-bored engine block from Naborsstored Automotive.  Sprayed all polished surfaces (cylinders, lifter bores, bearing surfaces, crankshaft, camshaft) with WD40 Long Term Corrosion Inhibitor (a “sticky” oil), wrapped it in plastic and stored it in the shed until other preparations are completed.  The engine compartment needs to be cleaned, primed, and painted before the engine and transmission can be reinstalled.  Aside from degunking,  grinding, and sanding the engine bay, there was one problem.

During the years that the car sat idle, the battery leaked acid which rusted away the metal floor of the battery niche. The fix was to install sheet metal to replace the niche floor, supported by angle brackets screwed to the remaining side metal.  Test panels were cut out of  ‘foamcore’ to get the floor shape exact before cutting the sheet metal. After assembly, fiberglass cloth was applied over the joints to seamlessly conform to the original curves of the niche.  The repair is solid and strong. Sanded smooth, primed, and painted it appears to be original.

BatteryNiche

1) Bracket installation, 2) sheet metal screwed to brackets, 3) fiberglass, 4) sanded and painted

And here is a photo of the engine bay after applying primer and paint.

EngineBay

The color is an original 1966 Ford option called Mariner Turquoise metallic.  The car, currently white, will be two-tone.  The body will be Mariner Turquoise and the hardtop a pearl white.  The interior is a lighter turquoise vinyl and will be restored in that color.

Next post will be engine block prep and re-assembly.  Stayed tuned!  And Thanks! for visiting.

The goal is to restore the T-bird to as near factory new as possible. That means disassembling  most of the car, de-rusting and repainting individual parts,  replacing worn out components, and reassembling.  Luckily, there is minimal body work required — there’s no frame damage, some minor dents and a few rust holes.  Body surfaces will be sanded, primed, and repainted, including the engine compartment, underside, and chassis.  Undercoat will  be applied inside fenders to reduce road noise and prevent future rust.

We recently removed and de-gunked the C6 automatic transmission, to be overhauled at a local trans shop.  Now the priority is to clean, prime, and paint the engine compartment so that the C6 and engine can be reinstalled.

c6

During the cleaning we noticed that the front stabilizer bar (sway bar) was bent.  Drive Line Service of Atlanta (770-242-9365) was able to partially straighten it for  $20.  However, we’re searching the web for a replacement part. (If anyone has a lead on one, please let me know.)

Another problem is that over time the battery leaked acid and rusted out the battery compartment, which will require some complicated metalwork to remedy.  We designed a metal insert using CAD software but still,  effecting a seamless repair will be a challenge.

Almost everything in the passenger compartment (seats, console, carpeting, etc.) were removed for rehab.  The seat covers are in good condition.  However the dashboard is severely sun-dried and cracked.  The vinyl door panels and headliner are also damaged from exposure and age.  Re-covering with new vinyl is not too difficult, but as of yet we haven’t been able to source vinyl that matches the original color.

Removed the dual exhaust pipes, which are in great condition.  Just need to be sanded and coated with high temperature paint.   The resonators and mufflers are rusted out and will be replaced with new.

OK, that about brings the project status up-to-date.  Future posts will feature work in progress.  Thanks for visiting.

The first major task was to remove the engine for overhaul.  As it turned out it wasn’t.   Turning, that is.  The engine was frozen, which made removal all the more difficult.  The last step requires removing the four nuts connecting the flywheel to the transmission torque converter, which requires rotating the flywheel to access the nuts, which was not possible.  What finally worked was to slide the engine forward just enough to create a narrow gap (about 1-2 inches) between the engine and trans, and then slip a wrench in to loosen the nuts.  Got them out after a day of frustration. Even so, one of the nuts had to be broken off.

After removing the engine and mounting it on an engine stand, the next task was disassembly.  Some of the pistons were rusted to the cylinder walls.  Those had to be removed by drilling several holes in the piston heads and collapsing them toward the center (using a cold chisel, a hammer, and delicate brute force) to relieve pressure against the cylinders.

oldpistons

Once extracted, the rest of the teardown was fairly easy.  Note that it is important to catalog parts referenced to their original locations if the parts are to be reused in the rebuilt engine.  This is especially important when extracting the push rods and hydraulic lifters.   Throughout the restoration it is good practice to collect and store parts in plastic sandwich bags with locations written on the bags with a Sharpie permanent marker pen.  Use string tags to identify both sides of all electrical and hose connections.   Take photos of large or complex assemblies before taking them apart to aid putting them back together.

block

After some internet research and phone calls, we stumbled upon a small racing shop that could re-bore the stripped engine block.  A machine shop referred us to Nabors Automotive (770-982-9821, TimNabors@bellsouth.net) in Snellville, GA, which  turned out to be an auspicious accident.  Owner Tim Nabors is experienced, highly knowledgeable, informative, and  helpful.  The work was high quality and not too expensive. Tim’s advice was priceless.  They vatted the block and crankshaft, re-bored the block to .030 over, and inspected the crank and cam (both reusable).  We ordered new pistons, rings, and bearings from Summit Racing and Nabors checked the pistons for fit and installed the new cam bearings.   He recommended tapping out the oil plug holes in the block and inserting hex screw plugs.  That’s safer than using the aluminum cap-type push-in plugs, which can potentially be installed crooked and leak.

Stay tuned, there’s more to cover to bring this current.  Cheers!

In July we acquired a 66 T-bird from a farmer in SC.  It had been sitting in one of his fields for 17 years.  The body was in surprisingly good condition,  the motor we assumed would need overhaul.  Here are pictures from July, before work was started on the car.

Before

Subsequent posts will bring progress up-to-date.  Check back soon!