Short block long stroke engine

[ill_will]

I was asked some questions about the camshaft sensor and so thought I'd do a quick update.

The photo a few posts up of a 3D printed prototype used a separate hall sensor and Deutsch Motorsport connector, with magnet mounted inside a nylon rotor arm (ignore the orange rod coming out the side):

I'd gone down this route as I couldn't find a very compact OEM hall sensor, but needing to pin the connector was a hassle and the crimping tools for this connector type are very specialised.

The housing is machined from aluminium, has two Oilite flanged bushes, and the shaft is a shortened aftermarket Lucas one (Powerspark I think?)

Subsequently I found a pretty compact Bosch hall effect sensor and decided this would be cleaner.

The housing diameter works out a little smaller than the first design. The plan is potentially to heat shrink the steel single tooth wheel onto the shaft, cut down as required, although for the prototype I'll probably use a grub screw to get the orientation where it's needed. This connection detail is one area I'm not totally happy with. It needs to take axial thrust load from the gear drive.

Per the powerspark design a nylon thrust washer sits between the toothed wheel and the top bushing.

The shaft has a spiral oil groove and there is a drain back channel in the outside of the housing, per the original distributor design. There is also a small hole to allow any crankcase pressure that makes it's way past the bushes to escape.

[ill_will]

Here is the revised design, 3D printed (at low resolution, for speed, so the quality is quite poor.)

I am hoping to make up the steel toothed wheel and shorten the shaft so I can test it with an oscilloscope before programming up the housing to be machined. Figuring out a machining strategy will be interesting with the side boss, which may need some adjustments to the filleting to avoid long program run time.

[ill_will]

A couple of milestones passed in the last week.

I'm undecided about the easiest way to bed the rings in, and want to do this before trying to get all the injection kit set up and calibrated to avoid glazing the bores.

The plan was to fit the old carbs (function unknown) and a power spark distributor I have, and either stick it on a dyno, or build the car up to the point where it can be driven enough to do some third gear WOT pulls.

I put the engine on a floor stand, fitted the carbs, distributor, exhaust manifold, and set the static timing and set up the plug leads. This was a small faff as I've fitted a plate below the oil filler cap to stop spray leaking out of the cap, and couldn't see the cam lobe positions. One carb off and looking down the inlet it was pretty easy to figure out. I wired up a board with a couple of switches: ignition and starter.

Next, rigged up a fuel line with a hand pump bulb to a jerry can. In my old elan I had one of these fitted permanently in the fuel line in the boot, and used to pump it until you can feel the needle valves close before trying to start the car. Two pumps of the the throttle and it started on the third try or so. But was incredibly loud with no silencer, and it was 9pm and my garage is under someone's flat, so I laid out the centre pipe and silencer and ran it for maybe 30 seconds or so; firing nice and evenly, oil pressure 40 psi on the gauge.

With hindsight I probably should have taken off the fan belt, but hopefully no damage done. But a good point to get to nonetheless.

[ill_will]

The other milestone which has been blocking progress on designing the fuel injection has been not having the actual car anywhere nearby to take measurements from.

I got some quotes on Shiply and arranged to meet a bloke called Alan outside the garage where some of the car has been living since about 2010 or so. Armed with some bits of wood and zip ties everything loose was tied down and we loaded it up, covered it with a tarp and a couple of hours later it was next to the engine, near where I now live.

(Hah, looking at the photos I remembered doing this job was blocking starting the engine in the previous post because the coil was still in the engine bay.)

[ill_will]

I spent the day machining the main body of the cam position sensor housing shown a few posts back (which fits where the distributor normally goes.) It was challenging, with some 5 axis tool paths and tied up features (the main bore for the bearings.) The fixturing strategy I picked for the second operation wasn't great, and I wasted an hour or so figuring out a workaround for two of the five axis toolpaths which were causing the CNC controller to error.

Here is the final result, compares to the original prototype.