Liner Protrusion

[Ahl 4]

Hello folks!

 

After a long long time of it sitting doing nothing, I've finally got off my arse and started putting my mi16 back together. The storage for my non-running 205 is coming to an end and I need to get the engine in the car and working ASAP!

 

Anyway, I've got a problem with liner protrusion.

The liners and block were machined down to increase compression.

 

The block is fine, as are 3 of the liners, which protrude nicely (all about 0.05mm), but one of them is just a bit low.

It measures up ok on one side, just over the 0.03mm minimum, but is a bit low on the other, just below 1 thou (0.0254mm).

 

This is at the best position it can be in - I've tried swapping them all about etc.

The liners are also all within 0.05mm of each other.

 

I really need to get this sorted quickly, and would rather not machine the block again or have to get another liner and machine it down.

I should be able to fart on the block and alter it by 1 thou! Is there anything else I could do?

 

Thanks!

Ahl

[welshpug 1,622]

Nothing else you can do but get the block decked a little further or source another liner if you have tried swapping them around to find the best combination.

 

I'd be weary of using that due to the difference side to side not just its low protrusion, i.e its not square.

[Ahl 4]

True - though I reckon the liner height is within 0.02mm all round (probably less than half a thou across it) so surely that's ok as its within spec?

Assuming I got the block decked more to suit of course.

[Ahl 4]

I know the engineering guys will yell at me for this, but once I had a block and liner combination that I wasnt pleased with and I took a flat piece of hard wood, wrapped it in first 120 grit wet sand and used loads of wd40 and gave it a good fews rubs across the top of the block in a nice flat manner, then changed the paper to 600 and repeat and then 1000 and repeat to get back a nice smooth surface

When I replaced the liners I had liner protrusion that I was really happy with. Engine is still going after 2 years and is ragged everyday.

I will wait for the bashing from the engineers. lol

From here

 

Tempting!

Edited April 13, 2011 by Ahl

[swordfish210 20]

Are you measuring this with the block clamped down on a flat surface or just free standing?

[Ahl 4]

Free standing - well on an engine stand. Using a proper straight edge and feeler gauges.

[petert 550]

Take another 0.0015" off the block. The gasket will take up the difference in liner heights. They will still all be within spec. Protrusion should be checked without seals and block & liners squeaky clean. Provided they are square I think all will be fine.

[swordfish210 20]

Free standing - well on an engine stand. Using a proper straight edge and feeler gauges.

 

If it was decked though it would have been clamped down solid on a mill bed, it might just be a bit of flex in the block you are measuring.

[Ahl 4]

Ah I see what you mean, but the block wasn't warped - it was pretty straight before and after the skim.

 

I'm getting it skimmed down at some point next week, as per petert's suggestion. If I can find a spare good liner before then, I'll have that turned down instead as I can have it done pretty quickly.

 

Seats/liners are all squeaky clean as they should be.

Edited April 15, 2011 by Ahl

[swordfish210 20]

Fair enough, heres how i measured my liners:

 

 

No so easy to do if you don't have a mill lying around though

[Cameron 16]

From here

 

Tempting!

 

I remember when I was at college I skimmed / resurfaced a cylinder head in a similar way.. except I used a surface table with some wet & dry stuck down to it rather than a bit of wood. It actually worked really well!

[Ahl 4]

Fair enough, heres how i measured my liners:

 

 

 

No so easy to do if you don't have a mill lying around though

Or just prefer to do it the easy way?