[ROVERNET - UK] RV8 Blocks

[Robert Thornton]

Thanks Kent for sharing your experiences and thoughts on this.

>in the 12 or so SD1's I have had over the years, I have seen several
blocks cracked behind 
>the sleeve 

Presumably these have been 3.5 blocks which indicates they're not immune
from cracking in the same way the 94 mm ones do.

>His approach is to use an unflanged sleeve with a 360 degree step at
the bottom with the 
>sleeves "bottomed out" in the block before final decking

This would prevent coolant getting into the crankcase and the liners
dropping down, but I don't see how it would prevent it getting into the
combustion chamber by coming up between the liner and the bore.
Presumably flanged/top hat liners solve this problem because coolant
can't get past the flange at the top (which also prevents them slipping
down the bore).

I've had two 3.5s, a 3.9 and a 4.6 and haven't had a problem with
coolant loss on any of them to date.

Fitting wet top hat sleeves would allow the block to be bored right out
and oversize pistons fitted for a large capacity conversion.

Rob

-----Original Message-----
From: rovernet-bounces at lyris.ccdata.com
[mailto:rovernet-bounces at lyris.ccdata.com] On Behalf Of Kent Kinard
Sent: Friday, 13 January 2006 4:28 AM
To: rovernet at lyris.ccdata.com
Subject: Re: [ROVERNET - UK] RV8 Blocks


> Is Des Hammill overstating the problems? Has anyone actually fitted 
> flanged liners?
> 
> Rob

Hi Rob,
Few on this list will encounter the problems Hammill talks about because
we usually deal with earlier 3.5 blocks.  I have not put enough miles on
my P6B to get a good idea of the condition of its engine but in the 12
or so SD1's I have had over the years, I have seen several blocks
cracked behind the sleeve(coolant simply disappears, and upon removal of
the heads, one or two pistons appear to have been "steam cleaned.")  I
have been guilty of assuming that these were head gasket failures and in
one case I assumed improper assembly since all the head bolts were
loose, but that engine had had new head gaskets installed by a previous
owner.  I would not be surprised if the engine in my TR8 were not
suffering the same malady due to overheating problems in the past.  My
new machinist in Midland has resleeved a number of crossbolt blocks and
claims they have all held.  His approach is to use an unflanged sleeve
with a 360 degree step at the bottom with the sleeves "bottomed out" in
the block before final decking.  I will have to inquire further about
how much he heats the block and how much interference he allows (sleeve
and block cold).  For a street engine, I feel the reuse of good used
pistons (with new rings properly fitted) is acceptable when using new
sleeves.  The pistons should be very carefully inspected and measured,
but they can be individually fitted to the cylinders with good results
when new sleeves are used.  I do intend to build one top hat sleeved,
cross bolt block for eventual use in my P6B, but am not in a hurry to do
so.

Because of advances in technology in recent years, it is now possible to
  "bond" both aluminium and cast iron (but not to each other) by means
of low temperature, high strength ceramics which have the same expansion
coefficients as the parent metals.  It could be possible to bore the
cylinders completely out of the block and replace the entire cylinder
with a bonded in, hypereutetic aluminum wet sleeve...or a piece of
aluminum tubing with a pre-installed iron sleeve.  By bonding in the
sleeves, block integrity would be the same or better than "as cast."
It's just a thought....

All this being said, I have an adequate supply of iron 300 blocks and
intend to use these when practical in cars that are daily drivers. 
Because of the slight added width, it may not be possible to use these
in P6B's, but they are a good solution in SD1's, P5B's and Range Rovers.

  For us North American types, it eases the transmission choice problem
as well.  the eighty pound difference in front end weight is neglegible
in those vehicles.


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