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Re: [T3] 74/78 crank?

On 18 Nov 2003 at 20:04, Neil Verdon wrote:

>   16mm iirc with pistons in 16.5 mm available from vw 

I just checked one, and you're right. It's 16mm. I think I got a basket case 
engine once with the OS piston. The case was shot, but I've still got the 
piston here somewhere. 

16mm is nice, because it means that I could buy a 5/8" cutter, which would be 
cheaper in this part of the world, and would be just about .004" undersize. 
Shouldn't be a problem since there is a bevel on the top of the piston.

> at one time we did talk about the usefullness of childrens drinking straws
> set inside each other within your pushrods before you put the tips in.
> another method would be to solder one end and redrill the hole smaller would
> solder hold? mayby brazing ?

I think solder would hold, as long as it was fluxed properly. Brazing would get 
the tip too hot and would anneal it. You'd want to be very careful, because if 
a bit of this came loose later it would not be a good thing.

> another way to raise idle oil pressure slightly is to reface you oil releife
> pistons on a exact flat surface with wet and dry

I like this suggestion. If the cutter has any merit at all, then this 
suggestion is just as good and the 2 should work well together.

> i cant help but imagine how many thousands of litres of oil has to pass thru
> this point as an engine grows old it is bound to put wear there some are not
> even very true from the factory apparently!

If it wore, then the parts would lap together and seal better over time. It 
sounds like John is saying that the factory finish just wasn't the best there 
(maybe it's worse on modern cases.) It's possible that old cases were pretty 
good there and got even better as they wore in.

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

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