Re: Help w/Rover 3.9 piston choices

["James J." <m1garand@speakeasy.net>]

Dave,
   W/out any machining, the C/R is about 10.4, which is fine w/pump gas 
and aluminum heads.  A thicker gasket will lower that some.  As far as I 
know, no machining is required to pistons or head to make this combo 
work 'out-of-the-box', so to speak.  Depending on my rocker ratio, I'm 
gonna' make sure there is clearance between the valves and pistons, but 
that's it.  Hope to be there next month.
   If I recall, some 3.9 and later blocks had some ovality to the 
bores, so D&D recommends that you hone the bores to take the 255 pistons 
in +0.020.  That's what I did, for insurance, but individual engines may 
vary.  It's just too bad that these pistons can't be gotten 
off-the-shelf as hypereutectic castings.  There are other piston options 
if you are willing to re-sleeve the block.  Ford 2300 pistons come in 
around 3.75" if my memory serves me.  One person reported a non-fatal 
block crack when re-sleeved to 4.0" inches, so Chevy LS1 pistons at 3.9" 
might work if the deck-height is OK.  Wildcat, in the UK, makes a 
special 4.00" bore block (new casting, I believe) and cranks to take the 
vererable BOPR up to 6.0L if you can afford the price of admission (I 
can't).
   That Chevy LS1 looks mighty fine if you want to push the limit over 
4.9L, as does the Northstar, but you've all heard me drool over those 
before........


David Kernberger wrote:

> 5/8/04
>
> James,
>
> 	I have seen this build formula several times and in several places
> over the years.  What I haven't seen is specific information on the need
> (or lack of need) for milling of piston head and/or cylinder head, to
> control the C R.  Please tell us what you did/didn't do and about what CR
> you think you have, as a result.  I sure would appreciate it.
>
> ----------------------------------------------------
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