Vintage Thing No. 2 - Ginetta G21S

Horsepower whispering with a Ginetta G21S

Six foot of two by two timber isn’t in everyone’s toolkit. The day I helped my mate Pete Low re–assemble the engine in his Ginetta, neither of us had such a thing.

Pete’s day job is vicar of St Budeaux in Plymouth. This means the days off he gets are Mondays. Fortunately, last week I had a clear Monday so our packed diaries coincided for once and we were able to start work in earnest on his car. When I arrived at the vicarage, it was immediately apparent that he’d bought all the gaskets and assembled a fine array of hand and power tools. He’d even arranged for good weather.

Pete’s Ginetta is a G21S. He’d bought it with a reconditioned engine that needed re–assembling. The ordinary G21 has a 1725cc engine made by the now–defunct Rootes group for the Hillman Hunter range. The G21S has a special head developed by Holbay, which was used in the sportier Hunters and Rapiers. All we had to do was fit the cylinder head, carburettors and exhaust and theoretically we might get the car going.

Here we are contemplating fitting the rather special Holbay head

Usually, we work alone on our own projects but between us we seemed to do everything in double quick time. In fact, it felt even quicker than that. By mid morning the tappet gallery had all been cleaned and oiled, any old bits of gasket purged from mating surfaces and the cylinder head was fitted. We were very careful in torqueing this down correctly. There is a special sequence. Beginning in the centre, you work outwards and diagonally, from one stud to another. Deviate from this order and the head can be tightened down to the block unevenly. If it warps or sits awkwardly on the cylinder block, the head gasket can blow.

It is traditional, when rebuilding an engine, to have some nuts and bolts mysteriously left over. Quite why manufacturers should scatter surplus nuts and bolts around their engines has never been adequately explained but I speak from experience. And, following this tradition, I was convinced that the engine ran far better without them. Of course, poor running beforehand had prompted the rebuild in the first place but, even so, without those surplus fasteners I was convinced the engine seemed transformed.

Pete had anticipated the opposite with this rebuild. He’d laid in stocks of brand new imperial fasteners, anticipating that something must have been mislaid between the engine being taken apart and the car coming into his ownership. However, we lacked nothing. Thanks to his meticulous planning we even had a new set of manifold studs that we had made the Saturday before. The Saturday had been one of those days. Pete had bought some bolts for conversion into studs and at my place we tried to shorten them and cut new threads down their length. To cut a long story short we ended up taking my lathe apart and putting that back together. Our pooled resources of die holders were all slightly pissed so we couldn’t cut a thread squarely once the bolts had been shortened and great were the numbers of items hurled across my shed. Eventually, in desperation, I emptied my old paint tin of bolts over the bench and lo! there were some lovely studs of the right thread and only just a little too long. Goodness knows from which engine rebuild these were left over. I had so many, Pete was even able to make up a spare.

Pete had also done his homework on what had to go where and made sure nothing was missing. Just before lunch, there was a little bit of excitement when we couldn’t find a 3/8 to quarter inch reducing adapter in Pete’s extensive tool kit. It wasn’t lost. We just couldn’t lay our hands on it. Fortunately, the local motor factors were open until twelve and Pete strolled across nonchalantly and made his toolkit just that little bit more extensive.

We had the right number of pushrods but they weren’t labelled. These resemble knitting needles and sometimes manufacturers of one dabble in the production of the other. Their feet and heads fit respectively into the cam followers and the rocker gear and you are supposed to return them into their original positions. This is because the ends match themselves to the other components with use. Mix them up and engine building lore hints at dire consequences.

But, as the pushrods weren’t labelled we had no choice. They will just have to re–match themselves to different components. Whether this provokes any problems remains to be seen. Frankly, I doubt it. One thing that did intrigue me, however, was that one pushrod was noticeably heavier than the others, even just trying them out in your hands. Again, conventional wisdom suggests they should all be balanced and tend towards lightness so long as strength is not compromised. Time will tell, but I am quietly optimistic.

After lunch we adjusted the tappets using the old “rule of nine” method – it’s horsepower whispering stuff – and had a go at fitting the manifolds to our lovingly re–created studs.

It's this head that adds the S to the common or garden G21

We could get the tubular exhaust manifold fit over some of the studs but not all of them. It’s a classic 4–into–2–into–1 system. Essentially there are two halves, which are bolted together. With a bit of huffing and puffing we could get one end of the manifold over the end studs at one end of the cylinder head but not the other end. Beginning at the other end, it was the same story but in mirror image.

To make matters worse, the exhaust manifold was strapped up in heat shield binding with very sharp stainless steel clips. Pete heroically insisted on giving me the hammer while he held the exhaust manifold and its wrapping. Whenever he nodded his head, I hit it. Very soon there was blood all over the place.

By now we had been joined by Pete’s neighbour, an elderly gentleman who I’d met before at a private view of one of Pete’s motorcycle projects. Initially, Pete’s neighbour assumed the role of a spectator but gradually he became drawn into our glorious struggle, participating enthusiastically in all our brainstorming sessions and “what if” experiments with large G–clamps and blocks of wood, even joining in with impromptu bouts of first aid although he wisely steered clear of hitting or holding things.

After cunningly using up all Pete’s hydraulic jacks in a bid to gain what, in wrestling circles, might be termed a submission or a technical knock out, I came up with the suggestion of using a long piece of timber wedged between the two halves of the exhaust manifold. This, I reasoned, would spring the two halves of the manifold apart if a volunteer was prepared to dangle from the other end. That would allow the ground crew to slide the manifold down the studs and onto the expectant gasket, which was still in one piece despite its proximity to the danger zone.

The others did not favour this suggestion as much as I did. I could understand this having tried out far more sensible ideas that subsequently saw us relying on divine intervention to avoid serious injury. Our collective enthusiasm was tempered further by the fact that Pete didn’t have a suitable piece of wood. But his neighbour acquired a strange gleam in his eye and while Pete and I experimented with an even more extreme case of hydraulic persuasion, Pete’s neighbour quietly disappeared, only to re–appear with a lovely piece of wood.

It fitted perfectly and straight away. A little nonchalant yanking, and so, too, did the exhaust manifold. And yea, great was the rejoicing.

Verily, great was the rejoicing – until we realised that the curvature of the exhaust pipes was so tight at the front that we couldn’t fit the brass exhaust nuts that Pete had bought.

Our mood became darker as the manifold smirked at us while we pondered our next move. We could either take it off and modify it and shorten the stud and then re–fit it. Or we could leave it on, cut the stud down to the shortest length that would allow a brass nut to bite on the thread and hammer the manifold to make more clearance.

Toolkit abuse among the engine punks

Nobody had any enthusiasm for getting the manifold off again. We smartly dented the manifold with a socket extension bar and Pete dexterously shortened the stud with his Dremel while keeping everything still in situ.

At last we were able to fit the brass nuts and tighten them down. However, Pete was already planning a stainless steel snake pit system made by tube charmer Brausch Niemann who’s already sorted out beautifully fitted pipes for a number of Pete’s bike projects.

After that, putting the carbs on was easy. We replaced the radiator and began to work out the runs of the radiator hoses. Ginetta only made about eighty of the G21S so you can’t go into a motor factors and buy them off the shelf. The solution was to order a variety of Sparco hoses and joiners and to re–work them with Pete’s bread knife.

Looks like it should go!

We might have got the engine to go had I not found the remains of a multi–pin connector that was part of the electronic ignition system. At some point this had been pulled apart and electrical cables ended in what looked like woollen fluff. This was probably stainless steel wire or maybe even fire optics. This discovery meant that the Ginetta would not sing its song that day.

Pete really needed another angled Sparco hose for the bottom radiator outlet so we consoled ourselves with sitting in the car and then investigating why the bonnet wouldn’t fit properly. The Ginetta G21 bonnet is virtually the front half of the car and is hinged on the bottom of the front of the chassis. We soon discovered that the bonnet had been damaged close to its hinge mountings and had been badly repaired. In fact, it had been swollen with lays of poorly applied glassfibre mat that fouled the chassis. Consequently, it couldn’t be closed and Pete is now going to make a new part of the panel in glassfibre.

It was still a good day, though. We moved the car a long way to running again and nobody was really hurt or collapsed from bloodloss. Pete’s neighbour still has his length of timber ready for when the not–quite–fitting manifold gets retired and the manufacturers of the electronic ignition are going to check it through and send it back with some instructions, all for a very reasonable sum.

That special Holbay head bumps up the output to 95bhp and road test figures quote a 0–60 time of 8.5 seconds, which is faster than my Dolomite Sprint. And, like my Sprint, it has overdrive on 3^rd and 4^th gear, giving a total of six forward speeds. Both our cars need to get back on the road. Pete’s Ginetta will probably be first.

Ginetta's were always good looking cars with a distinct family resemblance. Nowadays we call this corporate identity and are the worse for it.