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Re: [T3] Type engine longevity


On 12 Sep 2002, at 8:10, Shad Laws wrote:

> > KeithP=> What were your problems with your T4's??
> > 
> > The head design is weak, 

> Absolutely false.  It uses a cross-flow design, which is superior.

I don't understand "cross-flow design." What does this mean?


> The factory used cheap sintered metal seats.  On the larger-valved T4 
> engine, this bit them in the butt.  First part of the solution: don't 
> use them :-).  We use machined metal seats.

To my knowledge the seats aren't the problem; they don't come apart, or do 
they? I would expect sintered seats to have the same expansion properties 
as solid. There are a lot of really good parts made by sintering, although I 
have no idea if these were "good" or not.

> And, we install them with a good interference fit.  This is all common 
> knowledge, and it works.

This may be the WHOLE solution. Does greater interference make these 
heads more prone to cracking? It certainly puts more tension stress on the 
aluminum.

-
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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