International Lancia Forums

Yes, that should be the way. A bit more compression by the domed pistons combined with the low rpm cams. For road use that's the best.

Let us know when it is tested!

Walter

An 818.303 engine with 818.100 camshafts is not an 818.302 engine.

Both the 302 and 303 engine pull smoothly from low rpm's. Quite an achievement by the Lancia engineers considering the small size of the engines. Both engines have an rpm point where the acceleration "kicks in". This is appr. 2000 rpm for the 302 engine and 3000 rpm for the 303 engine.

The engine in Tina, one of my 1967 coupe's originally was a 302 engine. When rebuilding the engine two years ago the head was ported, flowed, 0.6 mm skimmed off and fitted with the larger valves. The pistons are of the 303 type thus slightly domed. When assembling the engine I decided to keep the 818.100 camshafts and the 29 mm venturi's. I never drive the car at 170 km/h but I do drive it in town and on country roads every day. I prefer the higher torque at low rpm rather than the few extra horses at 6000 rpm. The engine is smooth, fast and economical but it does not have the `kick in` effect at 2000 rpm. It has it at nearer 3000 rpm.

I bough a new 302 head some time ago to replace the head with a standard 302 head to have it behave like a true 302 engine again. The head is still on the shelf as the engine is still running superbly after 80.000 km. However since a few days 98 octane petrol is no longer available at the gas stations in my area. The engine pinks occasionally with the 95 octane petrol. The new head will go on before the end of the year.

I would also like to change the pistons but that is a bridge too far at the moment. I will first try a somehwat thicker head gasket. I am pretty sure I will end up by putting true 302 pistons in the engine. The advantage of learning the hard way is that the knowledge sticks longer as it is not only in the brain cells but in the body cells as well.

I agree with the theory books that say that higher compression is only useful if there is more valve overlap.

Ciao Huib,

you said that 303 pistons are slightly domed respect 302 pistons. That means 302 pistons are perfectly flat on top? or are less domed respect 303 pistons?

And 342 pistons are different respect 303 pistons?

Do you have these different pistons? If yes, could you take some pics just to appreciate the differences?

Is there someone that can put some pics showing these differences?


ciao
Paolo67