89 951 engine overhaul

Talk and Tech about turbocharged 924/944/968 cars
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four0four
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Already learned that lesson on another car with some stainless brake lines! Ordered some nylon wrapped -12 tubing the other evening (mostly so I can get a jump on routing some of these things!). I'd be wrapping the stainless with some protective coating anyway...
Also - read up on how to torque the connections - many a good fitting/ hose has been ruined by cranking them too tight,
Noted! I do not want to buy these again :D

I think I've read somewhere that you can count the faces? Seems like a crude torque angle measurement, but I imagine it doesn't need to be so precise.

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chris white
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Interesting history on AN fittings (AN stands for Army/Navy). AN was designed for easy use by relatively untrained field maintenance staff. No torque wrenches, the hand tight and then face count is part of the design. It’s pretty low torque, most over tighten them and ruin the sealing surface

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four0four
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That factoid is ringing a (clearly dusty) bell, somewhere...I've always a soft spot for design like that.

Anyway, that package should be in soon. Still plenty of other work to do...At least the head and flywheel are out to the shop too :)

The lifters are all stiff (I can't really noticeably compress them - unclear if that's good), save one...which is firming up after several sonication and under-oil-and-vacuum cycles. I may still grab some other used ones to pick through...

On that note: I've seen some folks mention sleeving or boring up the cam box for different lifters. I don't know what kind of load the bores are exposed to, but it strikes me that a 1.5mm sleeve could be interference fit in order to use 16v parts...Ah well, if I had another engine to risk :)

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crackership
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they guy who built my head (Joshua at Valley Performance Racing) was adamant that the idea that squishy=bad on our lifters is just a crazy misconception - he said they should be squishy when out of the engine with no oil pressure, but they should be springy. He said very clearly
Springy/Squishy = good
hard = bad
soft/no springy = bad
-Dave

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chris white
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If your lifters are full of oil they will not be very 'squishy'....'squishy' is a very subjective term so thats hard to define. Maybe I would say that they are not squishy but that can be squashy.
Firm is good....unless its dry, then its bad.

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crackership
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I like "squashy". Henceforth, the appropriate firmness of 944 lifters shall be known a "squashy" if only to underline the subjectivity of defining firmness over the internet :)

(I'll obviously defer to your wisdom, Chris - you've built a lot more of these than I have ;) )
-Dave

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four0four
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They're pretty firm after coming out from under vacuum (and oil)! After how nicely that one cleaned up I'm probably just gonna run em as is. Regardless, that's a ways off!

In other news, the rear fuel lines are two different sizes pre- and post- filter. -6 AN works for ...one of them! -12 is huge btw, I'm worried now about routing all of that for the oil coolers.

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Latitude48
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I agree that -12 is large for oil lines. Years ago, I used -10 for the oil lines for my remote Canton filter.
Tom Pultz
- 1989 944 Turbo - Guards Red/Linen
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four0four
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It's been a while, but I promise this hasn't stalled out - just waiting! And, I've news:

I've got the head back - nothing fancy done, but in much better shape. Plus a bunch of misc, non-engine things.

Bearing Services just let me know my block is up, but they're skeeved out a bit by the different alloys (recall I've the 2618 Mahles) and recommending tighter clearances than @chris white suggested. Mahle suggest 2 -> 2.8 thou, Chris mentioned 3.15 -> 3.94 (0.08 -> 0.10 mm). Bearing Services were suggesting 2, maybe 2.5 with warnings about slap. I'll admit, this is firmly beyond my pay grade :D

Has anyone got thoughts on the matter?

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chris white
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you will get piston noise on cold start with about .006" or more clearance, Back when I used to use 2618 JE pistons in steel sleeves if you didn't hear piston slap when it was cold then you were going to have problems when they were hot at the track. Circle track guys used to call them the 'rattlers'.
2618 expands 15% more than 4032 so you do need more clearance.
if you are using nikasil or alusil you can be a little tighter
it also depends on planned usage. street cars can be tighter but high HP track cars need room for expansion and they are not being built for 150k miles.
Does all that help or just make it more confusing?!

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