[ROVERNET - UK] V8 Engine rebuild - surprised at professional advice

Kent Kinard kkinard at wcc.net
Thu Sep 21 15:53:03 BST 2006

Hi Peter (and Franc),
As usual, I agree wholeheartedly with Franc and would go 
so far as to advise staying FAR away from that rebuilder. 
 Peter, as per our conversation yesterday, the 3.5 block 
has the most aluminum around the liners and the liners are 
thick enough to take a .020" overbore easily.  The 
aluminum V8's seldom develope a compression ridge at the 
top of ring travel as other engines do because the bores 
cool so well, so the main question of how much to bore a 
block must be answered by measuring ovality (out-of-round) 
at the bottom of the bores.  Some Rover V8's have ovality 
problems from new, but generally come into round at under 
.020"  Any 3.5 that has good main cap register and no 
signs of corrosion is an excellent candidate for a 
rebuild.  The 1982 and later stiff blocks have a slight 
advantange, but only if the engine is going to produce 
more than 200 h.p.  If you have access to one of these 
blocks with matching crank, it will save you the trouble 
of machining the rear oil seal placement.  The wisdom of 
the .020" overbore 3.5 is born out  by the marketplace.  A 
gent in North Carolina had a set of Silvolite 3.5+.020 
9.6:1 pistons up for auction on Ebay.  They were bid 
through the roof!! Even D&D bid on them early on.  Don't 
replace the liners unless one is cracked and even then it 
may be cheaper just to use another block.  Use a crossbolt 
block only if you can fit it with flanged liners.  Never 
fit standard 3.9 liners to a 3.5.  Use special thin wall 
liners for 3.5 to 3.9 conversions.

SD1 type front covers are an improvement because of the 
larger oil pump, but condition is more important.  An 
early pump that shows no sign of scoring is far better 
than an SD1 pump that is scored or pitted.  Endfloat must 
be accurately set on either type.

It was really great getting to hear your voice.  We are 
looking at being in Vancouver, BC, again toward the end of 
September 2007 and will look forward to hearing your 
travel plans.  Your knees (and the rest of your body and 
soul) are in my prayers.

Kent K

On Thu, 21 Sep 2006 15:01:52 +0100
  Franc Buxton <fab at dcs.warwick.ac.uk> wrote:
> Peter_Mitchell wrote:
>> Following my posting this week re: rebuilding my spare 
>>'70 model V8 engine,
>> [...]
>> The engine rebuilder said that he would regard a 70's V8 
>>engine as scrap
>> value only. [...]
>> He offered me a 3.5 litre 'short' engine of 80's vintage 
>>that has been
>> relinered to 3.9 litres, for A$2900. [...]
>> I can appreciate that a professional might have 
>>reservations about
>> rebuilding an older motor [...]
>> I would be grateful for the input of members on the 
>>situation that I have
>> outlined.
> 	[Franc emerges from lurk mode for the first time in 
> 	I would recommend you get another opinion. I have never 
>heard of an
> engine 'developing' pinholes in the liners unless they 
>have gone _very_ rusty.
> Since when does cast iron or even aluminium just 
>evaporate? Assuming the liners
> were sealed against the bores nothing could happen as 
>far as I can see. Much
> more likely (and common) is that the liners in the 
>newly-rebored 3.9 conversion
> will slip. I suspect he might have reservations about 
>honing your block when he
> can sell you a 3.9 instead (excuse my cynicism, which is 
>born of experience!).
> 	Just my opinion, but I've seen a few V8s...
> 	Cheers,
> 		Franc.
> -- 
>Franc Buxton
> Departmental Safety Officer, Networking Technician, 
>general dogsbody
> Dept of Computer Science, University of Warwick.
> Die dulci fruimini
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