Get Stuck In!

10 01 2013

Plenty of decorating at home, as well as Christmas has meant a bit of a lull in the garage, but all that’s over now so I can get stuck in again.

Apologies for this next bit of the blog getting a bit techy, but it’s hard to talk about the inside of a race engine otherwise…

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The engine I bought was described as having done a ‘couple of races and a dyno session’, and was ‘nicely run in’ so I was contemplating running it as it was, but on dropping the oil and discovering an inch long bit of mangled shim on the sump plug I decided to strip it completely and I’m glad I did…

It’s always a good idea to strip an unknown engine anyway, to make sure it conforms to the rulebook for a start. I always make a document on every engine I do with every measurement, tolerance and part number with dates any parts were installed so I can ‘life’ them. All parts in an engine and indeed the whole car have a useable lifespan so you have to keep track of it all to minimise the chance of failure.

Off with the head first. I couldn’t find any markings on the head but it looked very nicely ported, but looks can be deceiving and  you never really know how good a head is until you dyno the engine. But no cracks which is the main thing and from the colouration the mixture looks to have been somewhere near. Valve springs are of unknown origin but are not Iskendarian ones like I normally use, but they will be checked and replaced if necessary anyway. Also it’s not got 6mm valves like most of the miglia runners use but I’m not too worried about that at this point. The valve guides have a small amount of wear so a set of colisbro ones have been ordered from LCP. Full roller rockers are all present and correct too. It has an external dry deck style pipe from the head to the block but unusually the headgasket is a stock AF470 and the waterways haven’t been plugged, but a quick email to Mike Jackson confirmed it ran cooler this way, the only downside is that like most minis it is still prone to head gasket failure from the waterways which dry decking normally eliminates.

The flywheel assembly came apart quite easily with the main bolt not needing much effort to remove – another good reason to strip and rebuild… It has an ultralight steel flywheel, with a steel backplate and paddle clutch  with a grey pressure plate – all pretty run of the mill stuff. Removing the flywheel casing I found a set of non-roller Jack Knight straight cut drop gears 1:1 ratio as per the rulebook.

The block was held to the gearbox by 5/16 allen bolts, and on splitting I found whoever last built the engine had shares in a silicone sealant company – it was everywhere!  Overdoing the sealant in engines is my pet hate.  With the block on the engine stand I set about stripping the impressive SH Engineering crank pulley and timing gear.  These really are a work of art and beautifully made and as SH says ‘they are designed to be the best, not the cheapest’! The crank pulley came off reasonably easily but I had to fabricate a special puller to get the timing gear crank pulley off which, whilst it took a little while, will be something I will be using in future – and I can now add ‘toolmaker’ to my list of talents haha… The rest of the timing gear came apart with no fuss and so did the backplate, cam and well used followers.

Next out came the rods and pistons. Rods are very nicely lightened A+ with ARP bolts, and the pistons are the obligatory Omega +020 with teflon buttons.  Then out came the crank that had been made to miglia spec by Rob Selby. This is another lovely piece of work with careful lightening of the webs as well as cross drilling to aid oil feed to the bearings at high revs. Both big ends and mains are at -010 and don’t need a grind but I’ll make sure Darran at LCP gives it a polish.

SAMSUNG

The gearbox is a Jack Knight ‘involute dog’ type. It has a standard uprated open differential. On stripping it down there were no obvious visible problems apart from the amount of ‘Blue Hylomar’ that was stuck to the centre oil pickup pipe, which would have caused a definite oil pressure problem. The pipe itself was looking a bit ropey so a new one has been ordered from Minispares along with some new diff output seals, bearings, shims and gaskets.

SAMSUNG

So, next job is the gearbox rebuild. Watch this space…

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