Part 1  by Ramon Wilson
Part four - by Ramon Wilson
I decided to have a go at making a 5cc version of the 2.5cc Oliver Tiger Mk 3. This beloved British made engine is one I have wanted to add to the others so far made but have baulked so far because of the rather complicated crankcase shape. It will be the first time machining a front induction crankcase from solid has been attempted and though the machining will be similar to the inlet on the rear induction Super Tigre (correct spelling!) made previously the addition of webs and the front bearing housing will add complications. However, hopefully with some careful thought and machining, along with a fair degree of fettling, the shape will evolve to give a reasonable rendition of the original casting.

The Mk 3 in its original production was made in six versions over the period 1953/4 to c1967/8. You will see (above) that the pillars that take the cylinder head bolts are extended. This is the version to be attempted.

The Oliver engine(s) were hand made and produced at first by John (A) Oliver in a home based workshop later to be joined by his son John (S) who carried on the business until his (John S's) retirement. It is a testament to the quality and performance that they did so in this fashion for some forty plus years. More or less from the start their engines were aimed at the competitor and were firmly targeted to the tethered model car racing world. Many successes in this genre were logged up both here in the UK and on the continent.

Eventually a cross over into aeromodelling was made with the developing sport of control line team racing specifically in mind. Quick and repeating successes in this area lead on to it being the engine of choice for control line combat and it had to some extent similar standing in FAI free flight power for a while, too. This success turned this well loved mark of engines into near (if not full in some eyes) legendary status even if the waiting list to own one was a long six to twelve months. The history of the Olivers, both father and son and their many engines are superbly documented in a book by John Goodall – now out of print I believe but well worth sourcing a copy if you have the interest.

Below GA for the Oliver Tiger.

(Ed: Click on drawings to download - for personal use only.)

Like the Eta's and Racers they are twin ball-raced which calls for some accurate machining to get the races aligned. The material is the usual 6082 (HE30) which is nice to machine without picking up on the tool. The blocks weigh near 600gms each so as usual it will be interesting to see how much is left.

As always the cases are first - no case, no project – and, as said, they are not as easy as past ones.

The blocks were reduced to the basic dimensions plus .5mm on each face and the centres of the two bores centre drilled.

Before attacking the boring a plug gauge for the main bearing housing was turned along with a gauge for screw cutting the rear opening. The bearing plug gauge was made a careful .015mm down on size and the housing turned until that would just slide in. That gives a push fit for the bearing proper which will be tweaked if required on assembly for a good fit.


The blocks were set up to do the main bore first by the usual method of  using a 'wobble' bar. The paper under the block was there to enhance the grip.


After drilling, boring and reaming for the crankshaft main diameter (12mm) the bearing housing was turned as described and tested with the gauge. I do not have really accurate measuring kit for this op - doing it this way gets as close as possible without ending up with a loose housing - final fit is down to the fitting itself.


Then the main bore was finished to size and screw cut for the back plate. This was done 'back to front' so that I could see when the tool reached the run out. (Tool is upside down)


With those ops out of the way the blocks were turned through 90 degrees and bored through for the cylinders.


With the four cylinder bolt holes drilled and tapped that finished off the preliminary machining ready to start milling the outer profiles


First roughing ops on the front ends.


Using the faceplate, faced off the backs to finished dimension and roughed to OD and ID of the front housing to plus 1mm. This area will be finished on an expanding mandrel for accuracy.


Then removed some of the side waste leaving .5mm to finish. Also set up and used some new taps to do the venturi holes. The scribed ring is to give an idea where the outer diameter will be.

Part one here. Part two. Part three. Part four. Part five. Part six. Part seven

Part eight Part nine Part ten



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