[Rovernet] Observations Concerning the Rover V8 engine family (read only if you have time and interest)

[Kent Kinard]

Hi Netters,
There are Hot Rodders and Purists and every flavor in between. Every 
attempt to "improve" an engine results from a desire to do something 
with it that the original engineers, product planners, and bean counters 
did not intend.

The Buick/Olds 215 was designed in the 1950's to be a "throw-away" 
engine which would last 100,000 miles or so by which time the cars in 
which they were installed would have turned to piles of rust.  It was 
supposed to be cheap to produce and turned out to be anything but, due 
to problems casting the block.

Blocks were produced with the same die cast technology as automatic 
transmission cases with one exception...the water jackets had to be sand 
cast.  Furthermore, adding cylinder liners (GM really wanted to avoid 
using liners.) introduced added machining operations and thus added 
expense.  GM's solution, placing iron cylinder sleeves in the core box 
and casting the block around them, didn't work, so GM cut it's losses.  
Abandoning the aluminum block altogether, but saving all the transfer 
tooling, they created a whole family of V6 and V8 engines for Buick and 
subsequently for every GM division.  Along the way, they attempted to 
solve some of the other problems which manifested themselves.

The problems.

1)Piston design-
Buick (and subsequently Rover) refused to use slipper skirt pistons 
because they were too noisy, so any increase in stroke meant taller deck 
blocks and longer connecting rods (to keep rod angularity within reason) 
and more weight.  This problem was eventually solved with the advent of 
hypereutectic pistons which can run tighter cylinder wall clearances, 
thus reducing piston slap with slipper skirt pistons and allowing GM to 
reduce deck height (and weight) on the 3800 V6.  Rover never used 
slipper skirt hypereutectic pistons.

2)Crank-to-cam span/camshaft base circle-
Because GM only wanted the engines to last 100,000 miles, camshaft lobe 
wear was less of a consideration than overall block size and weight.  
Camshaft lobe height (and thus valve train geometry) was compromised.  
Hydraulic roller lifters finally solved the problem for GM...or at least 
minimized it.

3)Oiling system design disaster-
Because the Buick V8 was designed in the "good old days," lubrication 
depended on oil with high viscosity (and thus high film strength).  We 
use 20w50 in our V8's.  A stock, never rebuilt, Rover V8 can exist on 
unbelievably low oil pressure as long as the oil is high viscosity and 
changed religiously.  If the engine is rebuilt, ALL oil 
clearances/bearing surfaces must be checked/renewed.  Not only must 
mains and rods be properly sized, but camshafts, lifters, lifter bores 
and CAM BEARINGS must be renewed.  Rover never supplied replacement cam 
bearings to my knowledge because they must be installed by a good 
machine shop with proper tools.  Rover engines have stepped cam bearings 
with a different size for each bore, smallest at the rear.  Later Buick 
engines use cam bearings that are all the same size.

Rockers and rocker shafts should either be replaced or oil restrictors 
installed in the heads. An alternative would be to convert to 
through-the-pushrod oiling for the rockers, something GM did in the 
mid-1970's but Rover never did.  Failure to control all clearances will 
result in oil being pumped to the top end of the engine and rod bearings 
being starved.  If using original rocker shafts, remove the end plugs 
and clean the inside of the shafts and check for proper oil delivery 
once reassembled. Pre-'95 engines can have their oil systems pressurized 
with a drive installed in place of the distributor.

Oil circulation takes too many right angle turns and main bearings and 
rod bearings are fed from the right hand lifter gallery (Yes, Fred, we 
can save another machining operation if we eliminate that central 
gallery that Chevy uses.)  The oil pump body and cover are cast integral 
with the engine front cover and, because the gears ride in an aluminum 
body, any dirt or debris in the oil wears the body and to a lesser 
extent the gears themselves.  An engine rebuild means new oil pump gears 
and possibly a new front cover.  GM and Rover both put a band-aid on 
this by using a crank driven oil pump. GM's band-aid works pretty well.  
Rover's not so much so.  Consensus is that it's not worth changing if 
you pay attention to the whole system.

4)Failure to positively locate the camshaft-
There is no camshaft retainer on engines up to 1995.  Forward movement 
of the camshaft aggravates the timing chain stretch/wear problem and 
produces erratic ignition timing.   Earlier camshafts (any that use an 
ignition distributor) must be machined to accept the retainer plate used 
on post '95 engines.

5)Cylinder head retention-
It is now generally agreed that only the upper twenty head bolts should 
be used, but I can remember back in the early '90's when the head 
tilting problem first became common knowledge.  GM eliminated the bottom 
row of head bolts on each side in 1964, but it took Rover until 1995 to 
address the problem.
Use studs and nuts for head retention anyway.  At 3.5 litres and below 
4,000RPM, the heads in stock form are quite adequate.

6)Main bearing cap fretting-
Always a problem, Oldsmobile tried heavier main caps with 12 point bolts 
on the Jetfire.  Rover increased the depth of the cap register in the 
block along with the other changes to the block made in 1976.    Don't 
bother to use a block that has "loose" main caps.  Use main cap studs 
and nuts or use a cross bolted block...although the last is still up for 
debate.

7)Cracking behind the sleeves-
Last but not least is the mysterious disappearing coolant issue, 
somewhat rare until the advent of the 3.9, it became really serious in 
large bore versions.  There just wasn't enough meat in the cylinder 
walls and wall thickness was dependent on the accuracy of the block 
casting.  It cost Ford several fortunes after they took over.  I can 
remember a huge stack of blocks behind the RR dealer here in town.  Many 
could have been saved, but Ford made sure they were all scrapped.  The 
problem was never completely solved.  4.6 blocks are better than 4.0 
blocks.  3.9 and 4.2 blocks have been sorted out over time.  The best 
ones don't have the tick-tick-tick that is easily mistaken for a 
collapsed lifter and if they run, the coolant doesn't disappear out the 
exhaust pipe and you don't have a puff of white smoke (steam) when 
started from cold.  Best blocks MAY be from early 4.6 equipped 
Defender's.  Because of cooling system issues, all P38 engines should be 
viewed with suspicion.

Summary:
The Buick/Rover aluminum V8 is an excellent engine when religiously 
serviced and used in its intended roll of producing good torque and 
smooth cruising.  Some minor things need to be corrected (ignition 
system, head retention) to enhance durability and performance, and the 
camshafts will need to be checked for lobe wear every 80,000 miles.  But 
as soon as you begin to extract power above about 200HP, correcting the 
design flaws becomes mandatory and increasingly expensive.

If you have waded through this post, I invite your comments.  Maybe I've 
missed something.

Roverly,
Kent K.