True/False and Essay Test Options

[Poor-sche Lover]

Here's a test for y'all.

Please state whether each statement is true or false. If the statement is false, please explain:

1. 94 mm cylinders can be bored out to 96 mm with no trouble.

2. 96 mm pistons/cylinders will fit on 2.0 Porsche heads with NO machining necessary on either heads or cylinders.

3. If exhaust studs are stripped, you can simply tap them out, and put slightly bigger ones in.

4. If the cylinders have worn to oval, so have the pistons.

In your own words, please answer the following questions.

5. What is crankshaft end play? On a related note, by holding onto the fan hub, I can wiggle the shaft in and out a little bit. Is this a bad thing?

6. What are the tolerances for ovality of cylinders?

I'm sure there will be a follow-up, but that's all I have for now. If you read my last post, "which heads?", (sorry, I don't know how to link) here's the deal. I have acquired a 3-stud 2.0 engine, with 96 mm pistons, but the insides are trash. I would like to put the 96 mm pistons in my 94 cylinders, bored out, with my 2.0 heads on my 1.7 case (with 2.0 crank). I know this really turns it into kind of a bastard, but I simply don't have the cash right now to send my heads to Len. Trust me, I would love to. Maybe I will next year. Anyway, I appreciate your comments.

[Allan]

I can only answer a couple.

1. 94 mm cylinders can be bored out to 96 mm with no trouble. Yes

2. 96 mm Euro pistons/cylinders will fit on 2.0 Porsche heads with NO machining necessary on either heads or cylinders. Yes

3. If exhaust studs are stripped, you can simply tap them out, and put slightly bigger ones in. Don't know

4. If the cylinders have worn to oval, so have the pistons. Probably

In your own words, please answer the following questions.

5. What is crankshaft end play? On a related note, by holding onto the fan hub, I can wiggle the shaft in and out a little bit. Is this a bad thing? It is the amount of movement of the crank through the case. It can be adjusted with shims behind the flywheel. I believe you want right around .003 - .004.

6. What are the tolerances for ovality of cylinders? Don't know

I'm sure there will be a follow-up, but that's all I have for now. If you read my last post, "which heads?", (sorry, I don't know how to link) here's the deal. I have acquired a 3-stud 2.0 engine, with 96 mm Euro pistons, but the insides are trash. I would like to put the Euro pistons in my 94 cylinders, bored out to 96, with my 2.0 heads on my 1.7 case (with 2.0 crank). I know this really turns it into kind of a bastard, but I simply don't have the cash right now to send my heads to Len. Trust me, I would love to. Maybe I will next year. Anyway, I appreciate your comments.

[maf914]

I will try #1.

1. 94 mm cylinders can be bored out to 96 mm with no trouble.

Yes, but... (IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif)

As I understand the boring process is supposed to take place while the cylinder is clamped in a jig with bolts torqued to the proper head bolt torque. This may be a little trouble for some shops.

Okay. Is that right? What have I won? (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

[Cap'n Krusty]

1. By the right machinist, probably.
2. No. There ARE NO "European" 96mm pistons. They're ALL aftermarket, and mostly
Japanese.
3. No. You REALLY should drill, tal, and helicoil the holes, although there are OE 9mm
stepped studs.
4. Probably, but many forged pistons aren't exactly round to begin with, to allow for
expansion.
5. "End play" better called axial play, is the spacing between the thrust bearing face
and the surface with which it makes contact. In this case, the back of the flywheel,
via shims. In many cases, it's determined by the crankshaft itself against a bearing
in the center of the crankshaft.
6. Ovality is a question I can't directly address without some research. Any GOOD,
experienced machine shop should be able to tell you. "Experience" meaning air
cooled engine experience.

The Cap'n

[tat2dphreak]

1. True, and it's recommended over aftermarket 96 cyls(except Nickies)...

2. true. but see "1" you should use the 94mm cylinders... but Cap't is right, there aren't "Euro" 96s... Euro 94s, not 96s

3. False. see Capt'n response...

4. not nessacarily, sometimes... the ovaling can also be caused by changing the rings with out honing the cylinders, IIRC

5. the tolerances and method of testing is well explained in the "how to re-build your VW engine" book...

btw, I only replied because it was a "test" Capts responses are more than adequate to answer your questions...

[Poor-sche Lover]

. . couple of quick things. . .

The actual exhaust studs are already out. What's the difference between helicoil and tapping new threads? I guess I'm not quite sure on exactly what helicoil is.

Second, as for the end play, I assume then that this CANNOT be tested unless the flywheel is installed. Right now, very little is still on the case. I still have on the oil pump cover, the distributor, and the little fan hub. This hub is what I can wiggle, and as I do, the distributor rotor turns. My wiggle is decidedly more than the .003 or .004.

[type47]

1) true, "no" trouble

2) ummmm, i didn't know there were 96mm euros. i thought the mahle 94 mm 8:1 were called the "euro" p/c set

3) there are exhaust studs that are 9mm x 8mm. i went to a vw show called a "bug out" (2x/year at manassas, VA) looking for exhaust studs (8x52mm). an experienced mechanic said they never came as a 8mm stud but as a 8x9x--, which is what i thought was a repair stud. anyway, the 8x9x-- "step up/down" stud seemed to be well known to the vw bus mechanics.

4) beyond me

5) the axial movement of the crankshaft in the case; axial being along the axis, parallel to the axis of the crankshaft

6) there is a little book for each model of porsche with lots of info/specs. if i find any info, i'll post.

[Poor-sche Lover]

no other comments? Yeah, this is just a bump.