DHC8FO

Have your machinist surface the head (which you allready need to do), then do bench test before the valve job. He may charge you $30-40 to do this but you'll know how bad the valves are leaking before you even get into anything else.

cruise98

Has the machine shop measured the bores and pistons yet? You need to know before making a decision. Those scratches do not look too bad to me.

If the measurements are within spec, I would re-ring it and be happy. If not I think Ski has the best suggestion for a fix, which is to use the Arias pistons from Tom Charlesworth. There are other options to repair it, but they take more time, and still cost money.

Laust Pedersen

Zero10, If you decide not to do major work on the cylinders, don’t touch (clean-up) the individual scratches. You can only remove material, creating more blow-by.
Btw, the most likely cause of the scratches is foreign material (bad air filter and such), not the ring ends.

DHC8FO, OK so you almost ended up in the Rennlist Hall of Fame. Joking aside though, I envisioned a 7” raw sleeve with 104/99 mm OD/ID to be machined/honed even thinner before and after installation. In that case 650 engines could be sleeved for less than $14 in raw material cost per engine (assuming a $9000 one time expense). Could this be of interest to some major Porsche engine re-builder?

Laust

Zero10

Well, the one that goes the height of the cylinder on #4 was the end of a ring. I can see the ground down spot on the ring. I wonder why it would do that?

Good call on foreign debris on the other scratches, I'm going to refine your guess to 'somebody pulled the spark plugs, and crud got down in there', from how everything sits, it seems to make sense.

I'll have the head tested before any work is done on it, good call.

I've been thinking and thinking about these scratches, and I just can't see losing that much compression to a few tiny scratches.
It just doesn't make sense. I'd bet if the head seals up, with new rings, and honed cylinders, I'd get new compression numbers again. It didn't burn any oil or anything (well a bit once it overheated, and it smoked white a bit sometimes too), so they can't be _that_ bad...

I wish things were simpler. I'm taking it into the machine shop tomorrow at 7:30AM sharp. I expect to hear back about it within 2 weeks.

Thanks for all the advice so far you guys, it's been invaluable (in the good way).

Redlyne_mr2

Damn Chris its amazing how much work you have done. Youve come a long way since our tbelt changing days. Call me anytime night or day if you need a hand 667-2244
Ryan

Zero10

Sure thing Ryan. It has actually been pretty easy compared to what I thought it would be. I slept in this morning, so I didn't take my block in yet. I'll have to take it in around noon.
So far I think the frustration of everything that didn't come apart how it was supposed to has been driving this project. I think if it all went as planned, I would have gotten bored by now

I'm just hoping for some good news from the machine shop.