> Can anyone tell me the difference between the 3.9L and the 4.0L blocks
(and don't write me to say 0.1 litre).
James, this may surprise you but there is no difference in
displacement...
The 3.9 and the 4.0 have the same bore and stroke.
The main bearings and the rod bearings are larger in the 4.0, and the
con rod length is longer.
I suspect the compression height of the 4.0 piston is shorter to
compensate for the longer rods, but someone else will have to verify
that.
The reason the 4.0 'name' was attached to the engine was to distinguish
between the 'old' and the 'new'.
I would say that either of the blocks can be bored the same. The 3.9L,
4.0L, 4.2L and 4.6L all have the same bore (3.70"). The 4.6 is
basically a 'stroker' 4.0.
Larry Hoy
http://pages.prodigy.net/larryhoy/V8EngineSpecs.htm
> -----Original Message-----
> From: owner-mgb-v8@autox.team.net
> [mailto:owner-mgb-v8@autox.team.net] On Behalf Of James Jewell
> Sent: Wednesday, May 22, 2002 3:04 PM
> To: MGB Newsgroup
> Subject: 3.9 vs. 4.0 V-8
>
>
> Can anyone tell me the difference between the 3.9L and the 4.0L blocks
> (and don't write me to say 0.1 litre). If it is a bore difference,
> could someone tell me what the stock bore of the 4.0 is, and what it
can
> be bored out to?
>
> Thanks?
> James J.
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