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

[Dennis Gallacher]

Great post Kent and one I shall keep for future reference...also as it has so much detail can I have your permission to cross post to The Rover Australia email group I set up, I'm sure there will be many on there who will enjoy your post..

For those looking for extractors check out Pop Browns site as they do block huggers that I've been told are very good and made to allow fitment of R V8 into small English tin engine bays.. http://www.popbrowns.co.uk/

Den...

-----Original Message-----
From: Rovernet [mailto:rovernet-bounces at rovernet.org] On Behalf Of Kent Kinard via Rovernet
Sent: Wednesday, March 09, 2016 6:17 AM
To: Rovernet
Cc: Kent Kinard
Subject: [Rovernet] Observations Concerning the Rover V8 engine family (read only if you have time and interest)

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.







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