[ROVERNET - UK] RV8 Blocks
R.Thornton at adelaidecitycouncil.com
Mon Jan 9 02:41:53 GMT 2006
Any one who's read Des Hammill's excellent new book on tuning the RV8
will have noticed his gloomy prognosis of the potential problems
suffered by it. In summary he identifies the major endemic weaknesses as
(1) 50% of all two bolt (pre 1994) engines suffer main bearing register
movement leading to fretting between the alloy block and cast iron
bearing cap which in turn results in cracking around the main bolt
holes, rendering the blocks scrap; while fitting ARP studs does help it
does not cure this problem; four (cross) bolt blocks do solve it.
(2) 50% of all 38A (1994 on) blocks crack. All but the 3.5 engines are
prone to suffer cracking behind the liners due to the thinner alloy wall
separating the bores from the water jackets on the 94.00 mm engines - he
claims 25% of 3.9s / 4.2s, 80% of 4.0s (cross bolt) and 15% of 4.6s
The high percentage of HSE engines is due to inadequate cooling/radiator
arrangement on the P38 RR (and Series II Discoveries?). He says Rover
recognized the problem and from 1997 started ultrasonically checking all
new blocks to determine the thickness of the block walls behind the
liners. They were given blue, yellow, red paint dots in the valley area
- blue was the thinnest (2.2mm +) yellow (2.5mm+) and red the thickest
(2.8mm+). The blue graded blocks were all made into 4.0 litre engines,
the yellow and red became 4.6s. The 4.0s will as a rule only tolerate
three major overheatings before they will almost certainly crack.
When the block cracks it invariably leads to the liner dropping down
slightly in the bore as the pinch of the bore on the liner is weakened.
The solution, he suggests, is to run a bigger radiator with a 72/4
degree thermostat, replace water pumps every 45,000 miles, and for an
absolute fix remove the stock liners and have the block fitted with
flanged (top hat) liners with a bead of silicone around the bottom -
that way even if the block cracks water is not able to enter the
crankcase or the combustion chamber and the liners are not able to drop
down. And always replace head bolts and especially stretch bolts with
studs because most of the cracking seems to occur adjacent to the bolt
The book has some good info and is far more detailed and analytical of
components than either of Hardcastle's books on the RV8 engine.
Unfortunately Hammill doesn't always identify his sources, though there
are chapters on JE Developments and Wildcat Engineering and he relies
heavily on Mark Adams for the efi chapter.
John Eales, though, doesn't seem to confirm Hammill's pessimistic
assessments of the Rover block because he says he has rarely had a block
crack with the hundreds of engines JE has built.
Is Des Hammill overstating the problems? Has anyone actually fitted
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