Engine time

by Darren on Aug.26, 2009, under Build

So, since finishing the build on the head there has been a considerable delay, and this has been because of parts supply issues. The problem is simple – there aren’t many pattern parts such as bearings, etc., available for the Felicia’s engine, and getting stuff from main dealers is just a joke; Skoda may well score highly in customer satisfaction for their cars, but the local agent’s parts service leaves a lot to be desired; if it wasn’t for sites such as vagcat.com it would have been impossible to even get prices for any of the parts from them, as it made it possible to look all the parts prices up before visiting; without this they’d not even be interested. The prices were astronomical in some respects, and there was no delivery time guaranteed either – it was essentially “order them and see if any of it turns up”. Hardly ideal when you need to get an engine rebuilt.

There are companies who specialise in older Skoda parts, and while I’ve got the parts I needed at a reasonable price, there were some issues with missing parts and damage to a bearing meaning that another week was wasted waiting for these parts to arrive, and typically these were parts that were necessary for even getting started with the engine, leading to a three-week delay before work could begin.

Building an engine is an odd thing; most people view it as a black art and something they’d never attempt, but in many respects engines are reasonably simple devices. However, building one that will work well involves a LOT of time being spent making sure everything is done not only properly, but in a manner that is optimum; everything about the engine needs to be measured and checked; bearing clearances, piston ring gaps, weights of pistons and con rods, etc, and all of this takes time – hours and hours, in fact. When it comes to things that need to be removed and replaced to measure (such as the thrust bearing clearance), then it can take an hour or two just to get this spot on.

The Skoda engine is a little different to many engines in that it contains “wet” liners – the ‘tubes’ the pistons run in are not a part of the engine block (unlike on many), but are a separate component, having up and downsides, the biggest of which is needing to be ‘shimmed’ to be the right height relative to the top of the block, and this takes a while fitting, measuring, refitting, etc., and making sure each one is right as well as the difference between each one. Once they’re done, the crank can be fitted, and then the rings (which need to be fitted carefully and not broken, as they are quite fragile), and then the conrods fitted to the pistons, and the pistons into the engine itself. All of this took a few hours, and left it looking like this:

engine bottom end built

Which is finally starting to look like an engine, rather than a kit.

Next up is timing of the camshaft – this is another area where attention to detail is crucial. Without turning this into a lecture, the camshaft controls the opening and closing of the valves that let air into and out of the engine. The timing of this is one of the most fundamental things controlling the characteristics of the engine, and not only do you need a particular camshaft (this one has a longer duration and more lift than a standard camshaft), but the timing of it in relation to the crank is very important. There are timing marks and keys in parts of the engine, but they have a range of inaccuracy, and checking the timing of the new timing chaing it was about 2.5 degrees out, which doesn’t sound like a lot, but it’d make a difference. To adjust this means making up an “offset key” which is a piece of metal with the top offset to the bottom, to rotate the sprocket in relation to the cam. Sounds simple. Took 2 hours to make.

Next was fitting the head, and here an error occurred; The head had 1.6mm removed from it to increase the compression, and therefore 1.6mm would need to be taken out of the rocker adjustment to account for this. I forgot, and bent a few pushrods when doing it up. Fortunately no damage was done (I removed the head to check this), and I had some spares already, so it only cost a head gasket and an hour or so. Once it was all fitted up properly, I set the clearances properly, and turned it over, and it sounds fine, all opening up and closing OK.

After this there was the oil pump and front cover to fit, which was straightforward, and then the sump. Once the (temporary) rocker cover went on, it looked done, except the flywheel and clutch were still needing to be fitted – this can’t be done with the engine on the stand, so some awkward lifting and use of blocks was needed, but it all went OK.

Then it was time for some final work on the gearbox, which I’d mostly done several weeks ago. However, I looked at the list of torques for each part of the gearbox and suddenly wondered if I’d done the crownwheel bolts (that bolt to the diff) to torque properly. I spent 10 minutes wondering if I had or not (I know I did originally, but then it was removed while I sorted out the clearance problems on the casing), and then thought there’s only one way to find out, and that was to take the gearbox apart and know for sure – the consequences of a bolt coming loose wouldn’t bear thinking about. It took an hour to dismantle and rebuild, which isn’t too bad, and as it turns out…. I had done them up. Better safe than sorry! The final assembly was done after cleaning the end casing as the rest looked so good it would be a pity to spare half an hour and have it look like an old shed!

The final bit to do was mate the engine and the gearbox, which never goes that smoothly as getting the gearbox shaft to engage with the clutch plate always takes a bit of fiddling, but it went OK.

So, after about a week of work, and about £1500, here’s the engine and gearbox, post-Sunseeker disaster: