Index- home                  

About us

Committee

Our Vehicles

Events Diary

Archived Events

Newsletter

Technical

Regalia

For Sale and Wanted

Adverts 

1970 Series 2, 2+2 E Type Jaguar Restoration Part 3

 

Work continues on the block & head.

The block has now been completely dismantled which unfortunately has shown the bores to be not quite as good as first thought, some degradation to the surface of the bores has occurred. With the pistons now removed it has revealed a number of the rings to be broken & others seized in the groves. The crank main & big end bearings are also suspect. Both the block & crank are at a machine shop awaiting diagnosis. New timing chains, chain guides and dampers have been purchased as a matter of course and a new timing chain idler sprocket bush fitted since it was suspect. Main & big end bearings will be obtained once the machine shop confirms the crank reground sizes.

Although the cylinder head looked OK it too has gone off to a machine shop to be checked over & pressure tested. Initial feedback is the head is OK but the valve guides are worn & to a lesser extent the valve stems. In any event it is to be skimmed. A decision has been taken to purchase new valve guides and circlips together with a complete set of inlet & exhaust valves.

Something that I never contemplated was to be a debate over whether valve guide bores should be knurled rather than replaced. I am more of the `old school` & thought they should be replaced either with steel or phosphor bronze, the latter however being more expensive but better than steel. Knurling the guides is an alternative to replacement but also a practice used by some racing bodies since the end result gives the valve guide bores less surface area resulting in less friction allowing for better lubrication.  A downside however is the guides do not last as long. In some quarters it is seen as a quick fix. Reading various articles it was/is more common in the US. Taking into account the car is only going to be used for social motoring and not for racing or alike steel guides have been purchased.

Pistons and rings are fairly readily available but again consideration to the cars end use has to be taken into account. Forged, billet or cast? Its not a race engine so high spec pistons are not thought necessary. As it turns out the machine shop have managed to release the piston rings so it looks like new pistons will not now be required only a new set of rings.

On detailed inspection of the block it was evident some of the liners had dropped. There was also doubt that if rebored they would not move again during the machining process. As with the pistons there are various options, flanged liners which necessitate the top of cylinders to be machined to accept the flange on the liner. This method stops the liner actually dropping. What material spec for the liner? The vast majority of liners are made from centrifugal spun cast iron or spun ductile cast iron, the latter being a superior spec and typically used for race engines. It was considered the best solution in our case would be to replace the liners with unflanged standard centrifugal spun cast iron.

Whilst the engine is away at a local machine shop work has resumed on the bonnet, more specifically trial fitting it to the shell. Since it is made up of new and `old` parts getting it aligned is proving a task in itself but we`re getting there! The front bumper seems to fit fairly well.

 

   

 

Mike Davison

July 2014