Reducing Compression Ratio.
Hi there Alfisti,
I have a fairly serious problem with my 1985 Giuletta 2L. I have just rebuilt my engine, but now have pinking/knocking problem, which can't be remedied succesfully by retarding the ignition timing.
The head was skimmed 1.8 mm a few years ago by a over eager tuner. Compression ratio now approx. 11:1. The car has 10.9, 280 deg cams, with porting also done.
Unfortunately I can't find another 1985 Cyl head. (It is different from the older ones as it uses a different inlet manifold and linkages. I would like to have the correct head fitted to the car, not one of the old ones)
What I would like to know is whether I can make an aluminium spacer, fitted beneath the head but above the head gasket, which will work reliably. Would like it to be about 1,2mm thick, to take compression ratio to under 10:1. I must obviously be a leak free installation. An engineering company informed my that they do it a lot on Toyotas (succesfully), but have not done it on an Alfa yet. I am still a bit unsure about this.
Also advice on thicker head gaskets would be appreciated.
Please bear in mind the car is driven quite hard and I intend using the car for Track Days.
Any advice will by greatly appreciated.