Just taken the head my 1995 1.3 Favorit due to the seemingly usual water loss and mayo under the rocker cover and found a pretty disintegrated gasket !

Unfortuntely the head is also in a pretty bad way with a very uneven surface.

Does anybody know just how much can be skimmed from one of these head without running into probelms of breaking through waterways and also increasing the compression ratio too much resulting in pinking and poor running?

Cheers

I wouldn't want to take much more than half a mm off a head, ideally. The stroke on that engine is about 75mm and the compression ratio roughly 10:1, so the height above the piston at TDC will be about 7.5mm. Take 0.7mm off and you've already raised the compression ratio to 11:1. I haven't got a head here to look at but from memory you shouldn't have trouble with waterways, they're considerably deeper than that. I once had a whole 1mm taken off a Skoda 130 head which was badly warped, and although it didn't last very long (the rest of the engine was pretty knackered, frankly) it didn't break any waterways.

But you might be surprised how little needs skimming off. A 'very rough' surface my well have irregularities of well under 0.5mm. I'd take it to a good engineering shop and ask what they reckon, simple as that.

you aint gonna break into the water ways, but a rough rule of thumb is 0.5mm max. as richard black has said above, you'd be surprised how little needs to come off, if however it does need a lot to come off then the valves will need reseating too or they are bound to leak, it's normally the two centre exhast valves that leak the most

Many thanks. Should be able to get the head skimmed at work so will be free and should be able to do 0.1 mm at a time and see how it goes.

Many thanks. Should be able to get the head skimmed at work so will be free and should be able to do 0.1 mm at a time and see how it goes.

id be suprised if the machine connot go down to 0.025mm increments tbh:)

Ithe compression ratio roughly 10:1

if the favorit he has is the same motor as mine (135L) is 8.8:1 if its the 136 i'm not sure but is something in the 9.ish

here in the dominican republic a lot of people machine the HG instead of replacing them and every HG that is machined is done in increments of very low value the valves are polished and re-seated and the valve seals are replaced... here it doesnt cost all that much.

skim the gasket itself??? doont think i would like to try that

skim the gasket itself??? doont think i would like to try that

i mant the head, what he's doing, sorry. to be more precise where it meets the block to seal the cylinder, thats what they machine level here, they also check the block for imperfections, the cylinder walls for cracks and the piston for defects or cracks

my mistake!