Bearings
Crankshaft End-float
Crankshaft Journal Sizes
Gudgeon pins
Oil Change Intervals
Pistons
Timing chain
Timing chain tensioner
Valves
Valve Clearances
Valve Seats
Engine
Pistons
Coventry Climax: JP 0464
Standard Special: JP 0459
(available to order from JP Engineering, PO Box 21, Greenacres,
SA 5087, Australia (fax 61 (0) 8 8261 9171)
Pistons are occasionally available at autojumbles or obsolete parts specialists (eg Wellworthy ref231, Specialloid M5, Repco HX 1602). Commonly marked as for the Flying Standard 10 engine, 1937-on. Some years ago, a spate of such pistons appeared at the Beaulieu Autojumble at cheap prices, most probably because there are very few Flying Standard 10’s around these days.
These pistons are almost always of the 4-ringed variety, with a plug in the bottom land to stop the bottom ring rotating, and potentially fouling on the hole tapped through into the cylinder for the retaining bolts for the camshaft follower housings. The Repco HX1602 piston does not have this plug however and no damage would appear to ensue from its deletion in that case. While some three-ring pistons have been available for this engine in the past, it is unlikely any will turn up, and their use is advised against as they have a habit of breaking the top ring.
The NOS pistons were generally extremely well made, but care should be exercised in selecting and using them now. This is because of possible rust pitting on the rings and the gudgeon pin. Mild rust on the rings can sometimes be removed by soaking in deoxidene (phosphoric acid) followed by careful cleaning with steel wool, but gudgeon pins should always be discarded if at all pitted.
Gudgeon pins in these engines are held in place with wire clips which can usefully be replaced with modern circlips.
The price of any NOS pistons should be weighed carefully against the cost of the new JP items, which come with rings and gudgeon pins.
Standard Special:
Main: 3M 2212 (note, this is a BMC B-series specification;
for Morgan use, the center shells have to be machined to a width of 1.187”
and the oil holes checked)
Big end: 4K/B 3071 (note, this is for the Austin
A40; each top shell requires a new offset oil hole drilled to match that
in the connecting rod)
Thrust: Federal Mogul 2056BF (note, this is the specification
for the Nissan J13 and J15 engines, and also listed for the Ford 100E engine)
Bearings are also sometimes available from obsolete parts suppliers or autojumbles (including, mains Repco 3k3064, Vandervell VP412, VP48272 etc, big-ends 3063, VP1369, VP411, VP226 etc) Standard Special bearings were as fitted to the Flying Standard 8/9/10hp cars from 1937-on, and some NOS bearings will be marked thus. Big-end bearings fitted to the early post-war Austin A40 are the same size and can be easily modified to suit
Once again, any NOS bearings should be checked carefully for rust/moisture damage.
Standard Special:
Rolon SR901 (note, requires removal of several links.
If a competitor product is purchased, ensure it has a removeable link)
Standard Special
T42425 (single row Triumph-type)
Valves
Standard Special
2131 ST (note, these are from the E3ES Mazda engine,
and require only slight modification to fit)
Originally, these were cut to a 30 degree angle. With the new Mazda (also Ford Laser in Australia) replacements, the angle is normally re-cut to 45 degrees.
Both inlet and exhaust should be set to 0.022” WARNING: A feature of this engine is an additional spring fitted to the bottom of each push rod to maintain a 0.015” clearance between the follower and the back of the cam. Never discard these springs or otherwise reduce the valve clearances. This may well lead to compacting of the valve springs (ie the movement is greater than their compressibility) resulting in broken rockers and/or impact damage to the push rods. In cases where the valve gear is unduly noisy with correctly set clearances, the reason is almost certainly that the oil ways in the valve rockers (which commonly have a felt or wire wick to provide a drip feed to the valve stems etc.) have become clogged.
Mains,
Shaft diameter 1.9995 – 2.0000”
Tunnel bore 2.1460 – 2.1465”
Wall section (bearing) 0.0720 – 0.07225”
Length 1.375” (ends), 1.187” (center)
Big ends:
Shaft diameter 1.7495-1.7500”
Tunnel bore 1.8555 – 1.8560”
Length 0.934”
(Note, these are specifications to match the original
bearings and may be marginally different to those listed in some workshop
manuals for the Standard 8-10 range of engines).
Tolerances should be 0.003” to 0.008
Original service recommendations were for oil changes at 2,500 mile intervals, with the sump removed and cleaned out every 10,000 miles. Some authorities have suggested that with modern oils these oil change intervals can be extended. This is inadvisable.
The difficulty, especially in dusty conditions, is the engine design itself. Oil return arrangements at the front and rear of the crankshaft are via scroll threads machined on to the pulley shaft (at the front) and the crankshaft (at the rear). These are effective in returning oil, but the front one especially is even more effective at drawing dust and other muck into the engine. Neither the by-pass filter normally fitted nor the full-flow modification which some owners have carried out can cope adequately with this. British cars from around the 1950’s period, used in Australia, had a propensity for main bearing wear, particularly the front main, for this reason.
It is recommended for this reason that the oil change intervals for this engine be reduced to 1,000 miles or 6 months, whichever the sooner.