Alex Spring's Oval

On top of having a new gearbox fitted , Alex had some engine problems . One of his IDA's had been pouring fuel down the 3&4 side , and general problems with getting it to run properly , meant that I was going to check the engine out .

As we started to take the engine apart , several problems became evident .

The engine had recently been upgraded from a 2007 to a 2276 , but there were no discern-able balancing marks on the flywheel . Also , the case had been machined for 94mm barrels , but not been spot faced , so the resulting edge that the barrel had to sit on , was about 1mm wide , not offering good support to the base of the barrel .

I decided to remove the heads , and check what damage , if any , that the over-fuelling problem had caused . The heads looked ok , except that the valve keeper locks had not been ground , and the valve could still spin . I have found that with dual springs ( such as these heads have ) , this will wear out the keeper grooves on the valves in a short time . The valve springs had no shims under them , and were not shimmed to the correct coil bind figure .

The combustion chambers were also some very strange shapes . The cc's were close , but templates were made , and the chamber shape was quite different from one to another .

The engine ended up getting completely stripped and rebuilt . There were no balancing marks at all on the crank/flywheel assembly , so this was correctly balanced .

The case was spot faced to give the 94mm barrels the correct seating surface , and I had some of our custom barrel spacers made , as with the previous build , the barrel heights were all slightly different .

The combustion chambers were reshaped , and the heads fly-cut for the desired compression ratio ( 10-1 ) . The valve keepers were ground so they didn't touch , and the valves were re-lapped in . Also the valve springs were shimmed to the correct amount before coil bind .

I honed the barrels to a finer that factory finish , and fitted new rings , in case any ' bore wash ' situation had occurred with the over-fuelling .

The piston heights ( deck height ) , were also checked and found to be a fair bit out , so this was corrected so that the piston heights were all within 0.002 of each other . The pistons were balanced ( this had not been done before .