of a New Machine - Building a Cobra Kit Car
Copyright 1996, Daniel J. Sommers
Part 17: What Went Wrong?
Saturday morning dawned picture-perfect. And more than one local weather forecaster agreed that both days of the first weekend in June would be without rain, with daytime temperatures in the upper 70s and low 80s. Ideal Cobra weather.
I walked around the car and decided to work from the ground up as I checked tire pressure, snugness of the knock-offs on each wheel, exterior lights, and horn. The right front tire needed a puff of air to bring it in line with the others at 32 psi.
Under the hood, everything appeared to be in order, and I couldn't detect any sign of fluid leakage. Coolant level was about an inch below the neck of the expansion tank, oil reached the full mark on the dipstick, and the reservoir that holds brake fluid for both the hydraulic clutch and brake system had plenty of fluid in it.
Just to be safe, I grabbed a flashlight and visually traced the gas line from under the car, into the engine-mounted, mechanical fuel pump, out of the pump into the final filter, and from the filter up to the big Holley double-pumper. Bone dry everywhere. Even so, I borrowed the fire extinguisher from my '66 Pontiac GTO, put it behind the passenger's seat in the Cobra, and made a mental note to purchase another extinguisher. Not that I've ever had to use one; it's simply prudent to have it with you - just in case.
Satisfied that the little car was ready to play with us, I spent the next hour on cosmetics. I removed every speck of dust from both the exterior and interior, finessed just a trace of vinyl protectant onto the instrument panel and glovebox door, then used cotton cloths and glass cleaner to make sure the windshield and stainless steel trim sparkled. Man, it looked good!
As I was putting away the cleaning supplies, Deb returned from the health club. She was as anxious as I was to venture out for the first time in a vehicle that we knew so intimately, and within 15 minutes we were ready to go.
Behaving like a couple of kids with a new toy, I jumped in the car, started it, and moved it out of the barn while Deb closed the door and locked up behind me. Over the roar of the big engine, I bellowed the now familiar "Watch out for that sidepipe!" warning as Deb opened the door to get in. Apparently, she recalled my melted-sock incident and nimbly settled into the passenger seat, clearing the sidepipe with room to spare.
We both buckled up, and Deb popped open the glove box to tune the radio to a local oldies station. Even with the engine running, the compact antenna and RF amplifier hidden inside the trunk pulled in a clear signal. And the glovebox mounted radio with small kick panel speakers did a good job of filling the car with sound. Quite impressive, actually.
Although we had a high level of confidence in the new Cobra, our plan that day was to just drive around town, staying close to home in case anything should go wrong. As we drove, I checked the gauges frequently, making sure that oil pressure, oil temperature, and coolant temperature were always as expected. All instruments looked good, and the engine sounded healthy.
When you're in a Cobra, everyone who sees it is influenced by its magic. It doesn't matter what they're doing, where they're going, or even if they care about cars. They look. They point. They smile. It's a car that seems to make everyone feel good. Try it sometime.
Rather than driving aimlessly all afternoon, we decided to stop at World Auto Parts to show Frank what finally happened to the motor mounts and radiator hoses he had tracked down for us. Frank was thrilled with the result as we opened the hood in his parking lot. Of course, every employee and customer in the store came out to look too. Grinning from ear-to-ear, Frank answered questions about the car and the engine. I think he was pleased to know that his knowledge and experience helped us complete the project.
After that, we headed toward a casual restaurant about 15 miles away for a late lunch. The Cobra performed flawlessly, even through stop-and-go Saturday afternoon traffic in a few places along the way. Concerned about parking lot dings, we found an isolated spot in the restaurant lot and placed the Cobra out of harm's way, while we went inside for burgers and fries.
On the way home, we decided to attend a cruise night event that evening. It would require traveling on a 10-mile stretch of superhighway, but with more than 100 trouble-free miles on the odometer, we didn't give it a second thought. On the way into the driveway, I stopped to get the day's mail, then continued to the barn and parked the car inside.
Fully aware that the Cobra's engine was still tight, I kept the revs down as we drove between 55 and 60 mph for about 10 minutes on the way to the event. I couldn't help but think about what the car would be like after the break-in period - when I could really use all the horses hidden under the hood. On the highway, the little Cobra did not disappoint; it rode smoothly, tracked as if it was glued to the pavement, and attracted more grins, stares, and thumbs-up gestures than Deb and I had ever seen.
It was about 5:30 p.m. when we pulled into the far end of a large parking lot at an older, not-so-busy shopping center. All eyes were on us as we slowly made our way past a row of 50 or 60 classic cars that had already gathered for the evening. Crawling in first gear, the big block with the lumpy cam announced our arrival as it bellowed through shiny sidepipes. It was definitely a Kodak moment.
Within minutes after propping open the hood, a small crowd of fellow car enthusiasts gathered and milled around the Cobra. Deb and I knew many of them from years past, when we enjoyed cruise nights and car shows in Deb's '57 Thunderbird or my '66 GTO. For the next several hours, we "talked cars" and answered questions about the Cobra: "What color is that?" "Who did the paint?" "Where did you ever find a brand-new 427 side-oiler?" "How long did it take to build it?" "What's it got for gears?" "Why didja put safety wire on the knock-offs?" "Do you have ERA's phone number with you?"
The sun had already set and there was a slight chill in the air when Deb and I decided to call it a night. The fact that we were about to power up and drive away attracted yet another group of people, curious about the delicious sound big-block Cobras make when the engine first comes to life. Deb and I buckled up, and I turned the key. Instantly, the engine fired. Our audience was not disappointed.
I checked the gauges as we left the parking lot, heading for the highway entrance ramp three or four miles up the road. Everything looked perfect. 80 psi on the oil pressure dial. Coolant temp approaching 180 degrees. A few amps of 12 volt current flowing in the right direction. And oil temperature just starting to come off the peg. Deb had the radio tuned to the oldies station; they were playing "Denise" by Randy and the Rainbows. All was right with the world.
Then, just as we approached the entrance ramp, I felt a slight skip from the engine, like a sparkplug misfiring intermittently. It caught me by surprise; maybe I was imagining things.
We turned left onto the entrance ramp, heading up a moderate grade to merge with moderate volume, late Saturday highway traffic. I was in third gear and fed the engine with my right foot to gain speed. There it was again. "Maybe cross-firing between number 7 and 8," I told Deb. This was a common problem on Ford FE-series engines, because of the somewhat unusual firing order. "Yeah, that must be it," I assured her. "A misrouted plug wire. We'll fix it when we get home."
The Cobra mustered the power to merge into traffic, but I stayed in the right lane - just in case. As we made our way home, performance continued to deteriorate. The skip was especially noticeable when the engine was under load. I slowed to about 50 mph and babied the car for the remainder of the short trip. Under light load, the engine ran smoothly. All gauges continued to report ideal conditions under the hood.
We made it home OK and decided to park the car in the service bay that evening. Deb and I planned to diagnose the problem the next morning after the engine had thoroughly cooled. With the barn's lights out and doors locked, we retired to the house, watched a little TV, and crawled into the crib around midnight. All evening, I had been mulling over the Cobra's symptoms in my mind, building a list of potential causes and cures. This thought process continued throughout the night - one of the most restless I can recall.
Very early Sunday morning, while Deb enjoyed her beauty sleep, I brewed a pot of hot coffee and headed to the barn. The Cobra looked out of place parked in the service bay. I opened the hood and compared the sparkplug wire routing with a picture in the shop manual, paying close attention to the wires running to cylinders 7 and 8. No problem here. All eight wires were routed exactly as Ford Motor Company had intended back in 1966.
One by one, I removed the sparkplugs, looking for evidence of misfiring. Nothing unusual. The plugs looked as they should: consistent color, healthy electrodes, and insulators without cracks or chips. I concluded that the ignition system was in good health.
Maybe it was a fuel problem? If a filter had clogged or the pump went bad, the engine could have been starved for fuel - especially under load. To find out, I hooked up my remote starter switch to the solenoid on the firewall and disconnected the fuel line at the carburetor. I added a three-foot length of hose to the line and dropped the end into an old coffee can.
After making sure the car was out of gear, I pushed the button on the starter switch. With the sparkplugs out, the engine cranked briskly. In a few seconds, gasoline gushed into the coffee can. Common sense told me there was plenty of volume and pressure to feed the engine. Probably not a fuel problem.
Having eliminated the ignition and fuel systems as the cause for the mysterious miss, I turned my attention to the third thing needed to make an engine run: compression. But what could create such a problem in a brand-new engine? Bad rings? Highly unlikely. A junk piston? Not from Mario! Burnt valves? Naw, that couldn't happen in just a few miles.
Just for yucks, I did a quick valve-lash check by jiggling each rocker arm. I knew that those positioned over closed valves would move a few thousandths of an inch; the ones pushing on valves in the process of opening or closing wouldn't budge. I started with the rockers over cylinder number one and proceeded sequentially to numbers two, three, and four. No surprises.
I did the same thing on the other side of the engine. Rocker arms over five, six, and seven jiggled (or not) as they should. But I was in for a big surprise when I came to the final rocker arm - the one positioned over number eight's exhaust valve. It moved about a quarter of an inch when I jiggled it!
Shaken by the experience, I re-examined the top of the valve stem, valve springs, and the push rod for signs of damage. They seemed to be in perfect shape. The problem had to be deeper within.
As I contemplated my next move, Debbie entered the barn, carrying a cup of fresh coffee for me. "Did you fix it?" she asked hopefully. "Not good news here," I replied, and went on to explain the morning's troubleshooting regimen in great detail. As I concluded my summary, we looked at each other and spoke one word nearly simultaneously: "Camshaft."
We decided that we should confirm our suspicion immediately. Within minutes, we unbolted the Cobra's hood and placed it out of harm's way on the other side of the barn. Next, we set-up a pair of powerful quartz-halogen lamps and focused them on the engine bay. Finally, we protected the tops of the fenders with suitable covers to shield them from dirt and dings. As we donned latex gloves to keep our hands from becoming oil-soaked as we worked, it occurred to me that our service bay resembled a hospital operating room.
After draining the coolant, it took about an hour of wrenching to pull the radiator, expansion tank, distributor, intake manifold, and valley cover. As I worked on the center section, Deb removed the rocker shafts and arms, push rods, and lifters in sequential order, placing each component on clean paper towels on a nearby workbench. Everything looked as good as new -- until she pulled out the rear-most lifter. We couldn't believe what a mangled mess it was. The camshaft had gouged the face severely, and there were several chips of metal missing.
We knew that we had gone as far as we could that day. Clearly, the engine needed a new camshaft and a set of lifters before it would run again. Fortunately, Mario had included the original documentation (cam card) from Crower Cams, the manufacturer of the camshaft and lifters. The cam card would make it easy to order an exact replacement from Crower on Monday.
As Deb and I put tools away and cleaned up, we talked about what could have caused the problem. Knowing how careful we had been with the break-in of the new engine - and the fact that we had driven more than 100 miles before the mysterious failure - convinced us that this was probably caused by "bad metal." That is, either the last lobe of the camshaft or the face of the lifter assigned to it wasn't cast, hardened, or ground to spec. These things happen; we were just in the wrong place at the wrong time.
At least we had identified the problem and knew how to fix what went wrong. It would be a matter of gathering replacement parts during the upcoming week, then spending a few more hours with the Cobra in the service bay next Saturday. Deb and I were already looking forward to next weekend's cruise night, confident that the Cobra would take us there.