First Restoration 1980/1 : The Engine


The engine was replaced by a 2.5 litre from a 1972 Triumph 2.5PI (less the petrol injection). This was rebuilt by the owner towards the end of 1980, with the help of the machine shop of R. C. Williams of Bachymbyd Garage, Llanrhaeadr near Ruthin, who rebored the cylinders (+0.030") and reground the crankshaft (+0.010"). This process would involve reboring in 0.010" stages, finishing to just under +0.030" by a few thousands of an inch, and finishing by honing (grinding with stones rather than cutters) to precisely +0.030".

All the moving parts were balanced by Howley Racing of Warrington. The new engine was fitted on the 14th December 1980 (mileage 104,027). All new components were fitted where possible. STP was used to coat all bearing assembies to prevent undue wear until the oil circulates on first start-up*. A parts list appears below (1980 prices, in today's money £1200+) :-

Part Supplier Cost
2.5PI engine (complete, less Injection) No. MG52078EBW Station Motors, Mold £10.00
Rebore (+0.030") & hone cylinders R. C. Williams, Llanrhaeadr £20.00
Regrind main & big end bearings (+0.010") R. C. Williams, Llanrhaeadr £20.00
6 Pistons (HEPOLITE 17753/K +.030"/.762mm) @ 11.75 (inc VAT) & Apex Rings E. R. Williams, Wrexham £70.49
Set of main bearings (GLACIER M4229SA + .010") E. R. Williams, Wrexham £8.60
Set of big end bearings (GLACIER B6433SA + .010") E. R. Williams, Wrexham £8.45
Set of thrust washers (Glacier W2171 S STD) E. R. Williams, Wrexham £0.98
Head gasket set (PAYEN HS2A572(SB) Mk2 Liverpool Autojumble £5.00
Conversion set (CS1A951 Mk2) Liverpool Autojumble £1.50
Oil pump (POL706) Edmunds Walker, Chester £23.47
Duplex timing chain (MOR3DR62 BorgWarner Morse TEC) Edmunds Walker, Chester £5.77
Crank oil seal ((HALLS NA744) Edmunds Walker, Chester £2.27
Timing cover oil seal (BL UKC1110) More & Gamon, Chester £1.66
Timing chain tensioner H. I. Jones £0.50
Oil pressure relief valve spring H. I. Jones £0.50
Crankshaft bush (1512013) H. I. Jones £0.50
Set of big end conrod bolts (UKC2598) Cox & Buckles, London £2.50
Camshaft keep plate (105114) Cox & Buckles, London £2.50
Oil thrower (119390) Cox & Buckles, London £2.50
Timing wheel tab washer Cox & Buckles, London £2.50
Crank/Pistons/Conrods balanced Howley Racing, Warrington £20.70
Flywheel/Crank Pulley etc balanced Howley Racing, Warrington £10.35
Flywheel bush - £
Rocker shaft, 12 rockers, new valve springs (valves polished & ground in) Heron Tractors, St. Asaph £53.41
TOTAL   £274.28

An article about my rebuild appeared in the February 1981 edition of the TSSC magazine "Courier". It appears below:

Note about end float, Kas Kastner, in his book 'Competition Preparation Manual' cites end float less than 0.010" as acceptable.

Below are the specifications of the Cylinder head and Camshaft:

Cylinder Head   Camshaft
Part No. (bare) 520873   Applications Mk2 PI MG
Head No. stamped 218225   Camshaft Pt. No. 308778
Casting No. raised 312388   Ring ID 1 wide
Height nominal (inches) 3.4000   Timing (Crank deg.) 25°/65°/65°/25°
Applications Mk2 PI MG   Cam Lift 0.232"
Piston type Flat   Outer Valve Spring 157229
Exhaust valve (mm) 32.0   Inner Valve Spring None
Pushrod length (inches) 8.125   Valve Spring Collar 105118 (pressed)
EGR hump Yes   Sample Collar Height 0.195"
Rear water slot No      

* Note, STP contains zinc dithiophosphate as an anti-wear additive. Modern engine assemblers tend to use Graphogen Assembly Compound, which is is a colloidal graphite paste in oil. To visit their website click the image below.