I WAS having my hair cut yesterday – yes, I still have hair – and got into the usual conversation with the barber. Masters of the scissors are often interesting people – it seems to go with the profession – and this particular lady was talking cars. Seems her family is heavily into Holdens, and her son with his team are building a way-out street machine, aimed at killing the competition whenever this new toy goes to a show. But she said that although they have successfully converted and fitted a full flip-front, and pencilled in wheel tubs and stuff, they are having major trouble with the doors.
Suicide doors. Doors that open out from the rear, which were all the rage in the 1920s, got this name because the wood-framed steel bodies of the time flexed like crazy after a while, so that on these mainly two-door tourers with wide door openings (which got even wider through rough and bumpy corners), a door would suddenly fly open and the driver or front passenger might leave the car and end up eating dirt and stones on the road. And get run over by a skinny back wheel as well. Hence the term ‘suicide doors’! So this team are trying to get some suicide doors happening, but are almost ready to burn the bastards. Their design engineering was right, the thin tinwork went okay, but after hours and hours of not-so-patient modifications and adjusting, those damn doors still don’t want to know. Seems they can get them to open and close, but the demon ideal body-fit just isn’t happening, and they are trying hard to figure out why. They want those suicide doors to work, so they can astonish all the lookers, but they’re still weeks away from that.
Talking of time and design trouble, even huge automotive companies can have their major problems. I was working for a large Ford dealership when the XAs and XBs were being pre-delivered and sold, and Ford brought out a special feature on one model of its family station wagon: a wonderful two-way-opening tailgate. The sales staff were going: “Rah rah rah, we’ve got this beaut new feature that will go great in selling our cars, so we’ll get more commission money.” Sold the cars, put the cash in their pockets, but then customers kept coming back with battered and beaten-up tailgates. These two-way tailgates were a regulation fullwidth lower horizontal door with a wind-up glass window, and once you wound that window down, by an ingenious system of linkages and locks and levers you could either drop the tailgate down or swing it open to one side like a door. Brilliant! So handy for shoppers and unloading at the beach. Shut it again once the gear was in, drive off and think what a wonderful new car you had bought.
Problem was, for whatever mysterious reason, this beaut tailgate would fall off at speed and go bounce-bounce on the tar behind the car, even though it had been properly locked. The customers were angry, the dealers were hysterical, and Ford Geelong was acutely embarrassed and expecting lawsuits over this. Seems the complicated instructions for assembling and adjusting all those links and levers on the assembly line were not being followed precisely, with time pushing the workers, and the dealers just checked that these doors opened and shut and didn’t understand the complex instructions either. So the shiny new tailgates fell off and caused chaos, and Ford Australia quietly withdrew that feature and the brilliant two-way tailgates were never seen again!
We just finished rebuilding an older race car engine, which among other things had chopped-off noses on the high-lift inlet cams. This sidevalve four has a special overhead-valve cylinder head, via pushrods and rockers, and the modified aluminium alloy rockers have this wild lift ratio of 1.5:1. So with a .340in lift of these inlet cams, the valves are opening almost half an inch, given lift losses from pushrod flex and the necessary valve clearance adjustments. The cam isn’t radical – it’s a 25/65, and sidevalve engines cannot tolerate any more than that – but the exhaust cam lobes were specifically built up to provide lots of lift, with about the same duration. That’s because the exhaust lobes work directly on the mushroom followers, which then work on the ends of the valves.
Anyway, I needed to know why these inlet cams were stuffed, remembering we were running high spring pressures to control the heavyweight inlet valves, but there was no sign of coil bind at full open where the dual springs compress solidly together. It wasn’t a lack of lubrication, as this wet-sump engine throws oil everywhere, and the cam-follower bases had only just started to break through the case hardening.
So I talked to Tighe Camshafts, and they couldn’t explain except to say it was probably a combination of heavy spring loads and extreme rpm on the relatively soft cast-iron lobes.
The decision was made to hard-face the lobes, regrind to the original profile, install the cam after checking the lobe noses were not working outside the base circles of the followers, and see how it goes. And after 40 hours of working on this engine, I will be real glad when it goes from my workshop, too!