[Supras] HELP: Weired piston height

[berniek at technicaldevelop.com]

Bob:

    Thanks for the thought.  It makes sense, especially hydraulic lock.  
I do have another short block here which is freshly rebuilt.  I guess 
the wise thing is to change it, and not leave it as-is.  The one thing I 
did not count on was dealing with the transmission and clutch nonsense 
to change blocks. 

       Bernie

Bob Shapton wrote:
> If the rod has a slight bend in it the piston height will be lower. What could 
> cause it to bend? ... blown head gasket at some point leading to hydro-lock 
> .... rope in #1 cylinder to prevent engine from turning while torquing crank 
> pulley to 170 ft/lbs .... or ??
>
> Bob
>
>   
>> Man, if I ever needed help from knowledgeable people in this good
>> group, 
>> now is the time.
>>
>> I got the head off my newly bought '91 turbo to lap the deck and
>> install 
>> a Cometic gasket and rebuilt head.  While cleaning the piston
>> crowns, I 
>> noticed that the first cylinder piston crown is about .100" lower
>> than 
>> the others.  Measuring it and piston 6 to the deck, the .100"
>> additional 
>> depth is always there!.  There is no vertical slop indicating bad 
>> bearings or a bad wrist pin.  That was tested by turning the engine
>> over 
>> to pull #1 piston down in the bore, and then tapping down on its
>> crown.
>>
>> All of the bores are just about at the factory initial size (3.270"
>> measured with an inside micrometer.  #1 piston crown looks fine. 
>> All 
>> are stock turbo pistons.  There are some very light scratches at the
>> backside of the bore but no top ridge in any of the cylinders. 
>>
>> This is the weirdest thing I've ever seen.  Is there any chance that
>> it 
>> was assembled with a piston or rod from a different year?  The
>> engine 
>> ran fine before disassembly.  Any and all suggestions would be very
>> much 
>> appreciated. 
>>
>>        BernieK
>>
>>
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