This is a bit of a sorry tale really. The vehicle, a Griffith 500 was being driven around a circuit and whilst negotiating a sharp corner the oil light came on momentarily. Even the few seconds that the light was on, was enough to cause significant damage to the internals of this unit. What had happened was that the oil had moved away from the oil intake pipe in the sump. This was due to the cornering forces experienced on the circuit, and in turn had allowed the crankshaft and its bearings to be starved of oil. This caused the crankshaft bearings to be badly damaged and a large amount of metal to circulate around the engine. This in turn caused the oil pressure relief valve to stick and the engine then ran very low on oil pressure which compounded the problem. Considerable damage has been done to the whole oil pump assembly which will necessitate the renewal of the front timing cover, oil pump gears and pressure relief valve casting. Also the crankshaft will need to be reground and re-shelled. A decision was taken to upgrade the engine at the same time as all these major repairs were done. The end result should be an awesome engine with huge torque and a much increased power.
The engine set up on the engine stand being taken apart and examined for damage. The crankshaft although heavily marked, luckily wasn’t beyond repair and would regrind back to serviceable condition. The timing case and oil pump were un-usable and most of the rockers were damaged or missing the hardened pads. Also the camshaft bearings had suffered damage and needed replacing.
The block has been hot tanked to remove all traces of corrosion and dirt, and also the bores have been honed ready for the new piston rings. The photo on the right shows the new main bearing shells fitted waiting for the crankshaft to be installed. The block has been dressed and degreased ready for the build.
The crankshaft has been installed and the main bearing caps fitted. The caps are held on with ARP Hi Tensile studs and washers, this allows a higher torque to be achieved without any risk of damage to the threads in the block. The flywheel is also fitted, this has been surface ground and the whole crankshaft assembly dynamically balanced.
The pistons have been fitted, just the last one to go. The block will have ARP cylinder head studs similar to the main bearing ones, certainly the way to go as it helps to prevent any head gasket problems when driven hard.
All the pistons have been fitted and here the big end bolts are being torqued up to the required tightness.
Here you can see the ARP Hi-Tensile bolts fitted to the block, the engine is now ready for the head gaskets and the cylinder heads.
The picture on the left shows the cylinder head cleaned and the new valve guide seals fitted. The right hand shot shows the valves fitted after having been lapped in and some of the valve springs installed.
Both the cylinder heads are now fitted to the block and have been torqued down to a higher setting than would have been with the original bolts. The next job is to time the camshaft to the crankshaft before fitting all of the valve train.
The camshaft being timed up to the crankshaft. For this particular cam profile, it calls for 111 degrees ATDC at full lift on No1 inlet valve. The camshaft is quite an extreme item at 305 degrees duration which will produce a fairly focussed power band at higher RPM, but as the car is used in competition, this is ideal for the sort of work it will be doing.
The rocker assemblies are completely brand new. The original shafts were unusable and the rockers themselves badly damaged. The new rockers are steel instead of alloy which are a lot stronger, ideal for high RPM on a track.
Starting to look the part now, rocker covers fitted and a new ported manifold along with carbon fibre trumpets. These are 2mm larger than the standard 5 litre ones which increases the mid range torque. The exhaust headers are also fitted as well as the fuel rail and injectors.
On the left the sump installed with new cap head bolts. Above is a breather take off fitting that I have made which will be connected to a pipe that feeds into an alloy bottle to contain any oil vapour or discharge. Although it is unlikely to have much oil in the bottle, it is a race requirement for such a system to be installed.
The engine is now as complete as is possible before being installed into the vehicle. It still needs the alternator, belts, plenum etc but these items will be added once in the engine is fitted.
The engine has now been installed in the car at the owners house and set up to run in order for an MOT to be obtained. It will then come back to me for tuning and final adjustments to be made.
The engine has now been set up and runs beautifully albeit with a rather encouraging exhaust note! Although the vehicle is just about road legal it is mainly used for track and circuit work. The lower photo shows the car in action on it first event since the rebuild, it took a second place in the morning and first in the afternoon. A good result all round.