When Tribulations Give Way to Jubilation – Kris Clewell’s Porsche 911SC Engine Build
When Tribulations Give Way to Jubilation – Kris Clewell’s Porsche 911SC Engine Build
The drift felt good. My arms were crossed and the big port 3.0 sounded great. The tach hovered at 6500-7000rpms. The M&K RSR muffler screamed. In a moment it changed for the worst. The changeover happened in an instant. I was shocked. Adrenaline pumped through my system and fear took over. How far can I drive it? What did I do? What could it be? The car was clearly misfiring. I worried about mechanical damage, but also damage from unspent fuel washing out whatever cylinder was dead. I coasted into a nearby parking lot. I was shaking. The unspent adrenaline made me feel ill, and the old adage “don’t build what you can’t afford to break” popped into my head. I called a tow service and waited alone in the car. I started it and ran around back to listen. Yep, it was definitely broken.
Like any other internal failure, its tough to know whats wrong without pulling things apart. That night I pulled a valve cover. A rocker arm dopped out and it was broken in half. Earlier engines (‘65, ’66, ’67) had forged rocker arms. The forged rockers are lighter, and are the choice for high performance valve trains. Unfortunately their strength can cause devastating damage in the case of valve float. If the valve hits the rocker arm and the rocker doesn't break, the result can be piston damage, cylinder damage, head damage, or worse. In 1968 Porsche went to a cast rockers as a designed weak point. My 1978 3.0 SC engine fell in the latter category. I had a decision to make. Rebuild the head and replace the rocker, or do everything....
The whole concept of “while you’re in there” can spin ridiculously out of control. There is a million things to do in a 911 engine while you’re in there. Some of you may remember my white 911 SC that I rebuilt a couple years ago and documented here. I did a top end rebuild on that motor to stock specifications. I spent most of the extra money I had that summer on it, and it looked great. The only problem is that it drove the same. I spent thousands of dollars and the car drove exactly the damn same as when I took it apart. It was a bit heartbreaking. I should have done more while I was in there. It was emotionally destructive enough that I sold the car. It sounds petty I know, but I don’t think I’ll ever own a nice “survivor”, or something stock. It bores me. It’s not about going fast, its about improving, crafting, and making something truly mine.
The original SC engine is a 3.0. In 1984 Porsche increased the stroke for the Carrera motors making it a 3.2. I planned to increase the bore keeping the stroke short. The early SC engines have bigger ports on the cylinder heads, but lower compression. Later, they had high compression but smaller ports. The horsepower was similar, but in my case, I planned to increased the compression. I wanted to build a short stroke high compression 3.2 motor with a nice set of cams to go with. I pulled the engine out and began the long road of trying not to screw everything up.
Taking things apart is easy. Disassembled parts don’t have to do anything but be disassembled when you are done. Keeping things organized however, is another story. I would hesitate to say I am a notoriously unorganized person, but I’m often careless. I pulled the engine out. I took photos from every angle. (I would later lose these when I dropped my iphone in the toilet) I bought a cart. I bought another table. It was stainless steel and I would be able to keep things clean and organized when I started putting everything together. I was lucky enough to have my good friend Aaron Hatz of Flat Six Inc here in Minneapolis stop over on multiple occasions and tell me how to make this project turn out like a fairly tale instead of a nightmare. It’s hard to write this part of the journey, as I don’t want to sound preachy, or that I’m a pro, who knows exactly what he’s talking about. I don’t want to dispense advice, this is just about what I’ve learned, and experienced. That’s as much of a disclaimer as you’re going to get out of me.
What I noticed most about learning to rebuild the long block, (I’d done a top end before) is the amount of cleaning thats necessary. I sat on a stool with a razor blade and a scotch brite pad for hours. I cleaned the case, cam towers, and other miscellaneous things neurotically. The last thing I wanted was the thing to leak. Having the case leaking oil would be a 30 hour job, and a minute by minute reminder of my carelessness. So I cleaned, and I scraped, and I cleaned. Overall through this process of cleaning and scrubbing, I went through about 2 gallons of brake cleaner and several packages of my wifes scrubbing pads. She never asked, but they were replenished whenever I needed some. While I was sitting on a stool with a razor blade, the engine tin, intake manifolds, valve covers, and hardware were all out being restored. All the hardware that could be replated was restored to its original yellow zinc luster. If I was going to take this apart, and spend the blood and capital to restore and rebuild it, I wanted it to look like I did. I didn’t want it to look like the same 25 year old engine I took out of the car.
Assembly is tough. I can rebuild the short side of an engine from a watercooled VW in about 4 hours. The flat six engine has approximately 100,000 o-rings many of which are installed in locations that cannot be gotten to replace without a complete tear down of the engine. I did things in stages. Cleaning was first, then I assembled the crankshaft and rods and laid them in the case. The case halves went together the next time out. Following that milestone, I waited for the cylinder heads to come back. The one with the bent valve also had a broken valve guide boss. It was probably usable, but the way I drive the car, and the investment I was making led me to search for a new head. I found a couple of heads, on separate occasions and had them shipped out to me. Each time they were junk. The valve guides were shot, and the valves were sunk into the heads beyond repair. They even had broken fins. No one knows how to package parts without breaking the fins it seems. The third head was perfect, and Steve at Headwerks here in Minneapolis delivered a set of heads that were so well done that I immediately felt I had to show other people on the internet what they looked like.
I found a set of overbored cylinders, and fitted them over the JE pistons I ordered. The compression ratio is 9.8:1. This makes the gas stations I can frequent a bit trying, but I wanted to get the most out of the engine without switching over to a twin plug set up. Engine Builder Supply here in the States was integral in helping me decide on what parts to buy. Valve springs, pistons, rings, cams, etc... They answered all my first timer questions without bother. Great folks over there. I went with a set of cams fairly close to what the 964 cars run. Since I was sticking to the factory CIS for driveability reasons, I was stuck on cam profile a bit. Too much overlap disturbs the metering plate and upsets the car especially at lower engine speeds. The good news is if I ever decide to put a different induction system on the car, I can pull out the cams without disassembling too far.
Cam timing is a bit of a job on these engines if you’ve never experienced it before. Being infinitely variable there are definitely a few ways to screw it up. Setting overlap with dial gauge sets the cams correctly for their profile. Frustratingly, I had to do this 4 or 5 times to get the cams exactly where I wanted them. At this point things were getting more disorganized in the garage. Reaching the point of cam timing took months. In that time I’d worked on a 240d in the garage, 4 different snowmobiles, the VW Golf, and my Tahoe. As such I started to lose things. Simple but one of a kind washers and nuts went missing. I wasted hours driving places to pick up new ones, or crawling around on my hands and knees searching for them in the garage. This happened over a period of time but in the end I found everything I needed, and the long block was together. I had quadruple checked many things, and would continue to do so through to the end. Paranoia took over, and I started second guessing myself on many of the things I did. A few times I got out of bed at 3 in the morning to check something. Once to see if I had put the oil pressure spring and insert in the right place. To my credit, everything I re-checked had been assembled correctly or put in the right place.
Over the summer the previous year, I had quite a bit of trouble with oil temperatures. It ran hot. really hot. It ran hotter than I want to admit here for fear of pointing fingers and gasps from the peanut gallery. What was I to do? I was 1000 miles away from home, and it was hot. I resolved that I needed an oil cooler. Since my car didn’t come with a factory cooler, I had to source the 1972 only lines, or make something. I stumbled upon some factory (overpriced) lines on ebay and bought them. I had the oil filter housing machined to take a thermostat and fitted it all up to a mid year brass oil cooler.
Assembling the fuel system and peripherals went smoothly. More missing clamps set me back some time, but with a meter and a half of snow outside, I was in no rush. Eventually there was nothing to do but stare at the motor as it sat completed hidden on the engine yoke hidden under a towel. But it was done, and all thats left was to slip the engine in and turn the key.
Fear is the great motivator. It’s more desperate than greed, and uglier than envy. It makes us do things and not do other things more than any other emotion. I put off trying to finish my 911T build for months. It sat morosely on an engine stand in the darkness of my garage while I put it out of my mind. I was terrified that the blood and capital I had spent building the engine would be for naught. It’s not that I had a lack of confidence in what I had done as much as I was afraid of the old adage that “shit happens.” To be more specific on the topic, shit happens, to me.... all the time. Sometimes I’m an idiot, and sometimes I’m unlucky. “Luck” is baloney, so usually my luck is predicated by some bit of impatience I’d had along the way. This time around, I was under the tutelage of the most patient builder I know. Aaron Hatz of FlatSix Inc here in Minneapolis. With Aaron around for much of the build his patience rubbed off. I had meticulously checked double checked and assembled the engine. Still, what if the old me was still the new me and I was cursed?
It sat for weeks, but eventually the engine install went easy. In and up. I unplugged the fuel pump to get oil pressure built up and tried to start it. I took deep breaths and felt a bit ill at the thought. It made a sad clicking sound that landed dead and flat on my ears. I had an “oh boy here we go” moment, got out, and whacked the starter with a hammer. I crawled back into the car and turned the key. The engine turned over too slowly with a dead battery. After 15 minutes of looking for a battery charger I was back in the car and started checking for oil pressure as it cranked. With the oil pressure and oil temperature gauges maxing out their needles I threw my head back on the headrest and stared at the headliner. After a bunch of wasted diagnosis time looking at the gauge I switched the wires on the two adjacent sensors. That solved the issue. I turned the engine over and stopped when I saw there was oil pressure. I called up Aaron to stop by for first combustion. It was something we had done together, and I wanted him to be there to experience it with me.
I plugged the fuel pump in and lifted up on the metering plate inside the CIS airbox until I heard the injectors start to spray. The car started immediately. All the fear I had washed away. The sound ripped through the garage, out the door, and back as it bounced off the neighbors homes. I felt like I had been dropped off a building. The adrenaline rippled through my stomach and traveled into the goosebumps on my arms. I’ve never run a marathon. I imagine this feels kind of like finishing one, except mine sounds better. After some minor tweaking I shut the car down, it was time to let mother nature do her thing, and wash away the salt of winter. The impatience was back and it would be a difficult wait.