A Few STUPID engine questions

[bhac3]

I have a couple of engine questions...I'm pretty much a "newbie" when it comes to VW aircooleds...

Ok, I have an AE 1600 DP out of a 72 super that I am rebuilding.

1. Deck height: If i am understanding this correctly, POSITIVE deck height is when the piston is BELOW the top of the cylinder when at TDC. I thought this was correct until a iread a blog and the guy explained it just the opposite. He was saying that what i described above was NEGATIVE deck height. Which is correct?
--deck height should be around 0.040" ish
--deck height is adjusted with shims at the bottom of the cylinder
--deck height is measured with the cylinders installed at proper torque
--i am assuming i should install the heads, then remove them before i measure my deck height.

2. Call me stupid, but it seems weird to me that there is no kind of "head gasket" used...or is there and i am just doing not so good research?

3. Should I replace the gland nut?

4. When the flywheel is installed and torqued, should the dowel pins be flush with the surface of the flywheel or should they be below the surface of the flywheel?

Thanks in advance!

[Woody Gee]

Semantics. Shoot for .040 to .060 thou of clearance ( I prefer 40) from the top of the piston being below the top of the cylinder. Some put the piston even with the top of the cylinder and use a .040 copper head gasket shim. If your using stock crank, rods and pistons you won't need any shims at all, as most of the time shims and head gasket shims are used to adjust for stroker cranks.
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[bhac3]

thanks woody...i was kinda wondering about the shims because when i took everything apart, there were none...and yes, i am using stock crank, cam, rods, pistons, cyclinders, etc

[Quokka42]

I won't drop the old "There are no stupid questions," because there are - but yours aren't amongst them.

1. What you are describing is negative deck height and what we are shooting for. Usually we use a plate to torque down the cylinder for this measurement. shoot for 52 thou with stock parts, 40 is the limit before you are in danger of the piston hitting the head.

2. The aluminium is soft enough to seal without a gasket as there are no head gaskets. Sometimes a copper head gasket is used to provide some of the deck height as it can compensate for machining errors better and can help with sealing turbo.

3. If you know the gland nut has not been overtightened in the past it may be reusable. The needle bearing inside is probably worn so it is good practice to replace it anyway.

4. The dowel pins need to be below the surface or they might interfere with the washer and prevent the flywheel being fixed correctly.
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There has only ever been one man who was perfect, and they nailed Him to a cross.

[mark tucker]

about the only time Ive seen piston hitting head was either after a bearing was dead, or 8000rpm+ shifts with about .025" piston to head clearance and .010"piston to cylinder clearance witch lets the piston rock decreacing the clearance and it was on bigblock motor.
I always check deck in 3 places, top, bottom&center, so i know what I have when the piston rocks in the bore.
But for the most part .040" is a good piston to head spec. aluminum rod motors will be different. you can use a head gadget or not thats up to you,I use them I dont like leeks.I also dont recall having tore down a vw non headgasked motor that did not have atleast 1 cylinder leeking some, at some point.just because it leeks uppon start up dosent mean it leek when hot... but it can. the copper gadgets also seal most imperfections when no gasket wont.(boogered deck,chattered deck,uneven deck etc) with that said they dont cure all ills, and sometimes require retorquing of the head studs. the empi headgaskets seem to be a lot softer than the bugpoop&cb gaskets that I have used, that can be an addvantage in some situations.they also squish more than the others.(but not enough to realy worry about clearance issues)

[bhac3]

thank you Quooka and mark. Much appreciated! those bits of info have helped immensley

[zac_atac44]

bhac3,

Great questions, I am just about to this point in my build and I am a rookie too.

[mark tucker]

and yes replace your gland nuts if they show some wear, if the flats are afu, or if it isant chromoly, there cheep $14~40. I cant tell the diff between any of them, that all need deburring of the flats befor usage so they dont dig into the washer.

[Quokka42]

Good tip, Mark.
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There has only ever been one man who was perfect, and they nailed Him to a cross.