Laziness and stupidity pretty much always revisit you at some point, particularly when it comes to cars.
About a month ago, inspired by the Jim Kartalamakis book "How to power tune Alfa Romeo twin-cam engines" (in the SpeedPro series, published by Veloce Publishing PLC in the UK) I had acquired a stock standard airbox and filter assembly for my Alfetta. The previous owner had plunked a set of 45mm Dellorto carburettors on the car (standard are 40mm), but had used short intake trumpets and sock filters in place of the standard airbox. Jim's book shows a nice picture of a reamed-out standard airbox that he swears is good for 200hp with the 45's.
"Hey", I thought, "I've got a drill and some grinding bits, that looks easy!"
It looked easier than the other stuff in the book anyway. High compression pistons are expensive, porting engines is not for beginners. My daughter won't let me borrow her plasticine for checking the interference between big valves and exotic pistons, apparently I'm only allowed to use it for making biscuit cut-out elephants. The airbox mod was cheap, didn't involve stealing children's toys, wouldn't take much time and would settle down that "what's next" fever that grips every car modifier on a slow afternoon.
Without the standard airbox (as you already know from a previous AutoSpeed article), there was the ever present fear of a fire under the bonnet to haunt me, along with the knowledge that the standard airbox had a much better chance of routing cooler air into the cylinders and supported the carbs properly. That was about all the extra motivation my fevered imagination required. Not only would the car be faster, it would also be safer! It's the sort of thing I could almost justify to my wife, even if she continues to regard me with the well deserved suspicion that tinkering with the car requires little excuse at all.
Anyway, my new (second hand) airbox gets clamped to the bench and I attacked the ports with the drill to make them big enough for the carbs. It took me some time, but it was a pretty reasonable job and I was happy with the results. Four nice, big, round holes. Kind of round, anyway. Big enough not to impinge on the hungry carbs for sure.
I was now eager to see whether Jim's magical 200hp might appear, even though I hadn't fitted big valves, ported the head or put high compression pistons in. I like to dream....
I bolted the assembly to the carbs, put the stabilising rod into place, clamped the crankcase breather hose into place and surveyed the scene with a satisfied eye. I then slung myself behind the wheel, started the poor old thing up and reversed quickly out for some seat of the pants testing on my favourite twisty nearby road.
To be honest, the only difference I could register was that the car was quieter. I kind of missed the gobbling, snarling and backfiring that the old setup made, the two carbs jumping and dancing on their rubber mounts without support made for some interesting progress sometimes. Also, I could now hear the centre tailshaft bearing whining, which was a bummer. Then, near home, I started smelling oil burning.
I looked around in vain for the inevitable early model Laser, Sigma or Camira smoking along the road ahead of me but rapidly came to the conclusion that the problem was with my Alfa.
When I parked the car, I gave it a bit of a rev in the driveway looking for the telltale blue smoke and could see nothing. I sighed the lonely sigh of the home mechanic. This engine was only a year old, I built it myself (always a concern, admittedly), It couldn't possibly have leaking valve stem seals or worn piston rings already.
What could possibly cause the car to start stinking of burning oil? Obviously, if it wasn't being burned inside the engine, it was dripping onto the exhaust somewhere, but why now? I'd only changed the air-cleaner. It then dawned on me, I had forgotten to check whether the oil breather canister (part of the filter assembly) was blocked or not. I ripped it off in disgust and I couldn't blow through it at all. I had just managed to blow the rear oil seal out of my motor in the haste to hit the road. 30 seconds of care would have saved me days of ripping apart the driveline attempting to extract the damn rear crankshaft seal and replacing it.
Right now, I'm only half way through the job, grease fresh under my fingernails and still annoyed with myself. It's much nicer spannering your car when you're adding something new rather than fixing broken things, especially when you broke them. Negotiations for the plasticine continue.
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