Follow the motion
under the cover.
The timing chain links the crankshaft to the camshaft. The virtual engine now lets you select each gear, the 62-pitch chain, tensioner, cam retainer, lockplate and bolts. Use it to learn the assembly and prepare a record of what is fitted to your car.
The factory chain pitch and count and follower dimensions are firm manual data. Supplier photos appear to show 20 crank teeth and 40 cam teeth; those counts need a direct check on the fitted gears. The CAD’s approximately 149 mm cam-to-crank spacing comes from an ideal taut-chain calculation. The real tensioner, mounting coordinates, tooth form, fitted cover and timing phase have not been measured. A supplier-listed UKC1110 seal (76 × 52 × 10 mm) and removed Spitfire-cover photo scale the current oval, but do not identify this car’s cover or seal. The revised cover and the photo-scaled housing rear flange clear the virtual chain and gears, but the revised pump station clears the virtual chain and cover. That station is inferred rather than measured, so these meshes cannot establish removal clearance. Do not use the model to set valve timing or choose a replacement chain on its own.
Timing-cover hardware: a front-view checklist
The factory Midget 1500 parts plate B84 lists 11 screws, one nut and 12 lock washers for cover 217790, without assigning holes. The Moss Europe 1500 parts catalogue, printed p. 127 supplies the missing front-view sequence: 14 positions A–P, with A at the upper central dowel and the remaining positions clockwise. It identifies two dowels, five short pan-head screws, six longer hex-head screws and one stud with a nut. That accounts for the 14 holes visible in a 211126 replacement-gasket photo. Moss uses replacement fastener numbers, so its codes differ from the older factory plate.
Photograph and label the fitted perimeter while looking at the front of the engine. Use the catalogue sequence below as a checklist, then record any different screw, stud, dowel or shared bracket. The CAD’s 14 hole centers remain photo estimates, so do not use them as a drilling pattern or assume this car has the listed hardware.
A, K · locating dowels
DP514, 5/16 in diameter. A is the upper central position; K is the second dowel.
C, D, E, F, J · short screws
SE605031, slotted pan head, 5/16 in UNF × 3/8 in, each with a GHF332 lock washer.
B, G, H, L, M, N · longer screws
SH605071, hex head, 5/16 in UNF × 7/8 in, each with a GHF332 lock washer.
P · stud and nut
TE605105 stud, 5/16 in UNF × 1¼ in, with a GHF332 lock washer and GHF201 hex nut.
Clockwise quick pass: A dowel → B hex → C pan → D pan → E pan → F pan → G hex → H hex → J pan → K dowel → L hex → M hex → N hex → P stud and nut.
View the four hardware groups on the virtual cover ↗ The model uses the catalogue counts and nominal 5/16-inch shanks. Its mapping of A–P onto photo-derived hole coordinates, head and washer sizes, and fitted hardware remain unverified.
The A–P letters give clockwise order from the front, not measured X/Y coordinates or proof of the hardware fitted to this car. The Moss list has no I or O position. It lists 207492 as the single-timing-mark cover and 217790 as the multiple-timing-mark cover; identify the fitted cover before using either timing scale. Confirm the actual fixings before ordering or tightening anything.
A photograph of a used 217790U cover also shows a raised metal collar around the crank oil seal. The CAD now includes that collar so the front face reads more like the sourced cover. Its opening follows the listed UKC1110 seal comparison, while the outer taper and projection remain visual estimates. The photographed used part does not establish the cover installed on this car.
What you can inspect in the model
Crankshaft gear and key
The matching 119389 single-row replacement lists a 35 mm shaft bore. Part 105115 is the catalogued half-round Woodruff key. The model now separates the key from its crank seat and matching gear, oil-thrower and pulley slots. Only the supplier's 4.75 mm key size anchors its section; the length, projection, angular position and exact slots still need checking on this engine.
Select key ↗ · Select crank gear ↗Pulley retaining nut
The 155357 parts listing identifies one nut retaining the Midget 1500 crank pulley. The STEP now extends the crank tip through the virtual pulley and shows the photo-style hex base and round collar separately. A Spitfire 1500 reference reports a 1 13/16-inch socket, which now sets the model hex; verify that size on this car. Its thread, seat and axial dimensions remain unmeasured. Inspect any washer or locking feature before ordering parts.
Select retaining nut ↗Crankshaft oil thrower
The 1500 exploded drawing places 119390 between the crank sprocket and pulley. A photo of 119390 shows a shallow dish and an inner notch. The new separate CAD part follows that shape, but its diameter, depth and fitted orientation are estimates.
Select oil thrower ↗Camshaft gear
The 838-205 product photo shows four offset mounting holes and a single row of teeth. The model separates the gear, lockplate, two bolts and the cam retainer behind them.
Select cam gear ↗Chain and tensioner
Sixty-two roller stations follow the factory pitch around an ideal loop. The 42425 shoe now follows the photographed curved strip and rolled eye. Its installed bow and chain contact remain unmeasured.
Select tensioner ↗Anchor and retainers
The 1500 parts drawing lists plate 43752, two RR610040 rivets, pin 33214, two WP18 washers and two PS103121 split pins. The model separates the anchor, rivets and grouped pin hardware, with estimated sizes and positions.
Select anchor plate ↗Followers and pushrods
Eight followers now use the factory 20.30–20.32 mm diameter and 44.45 mm length. Their bore locations, the pushrods’ lengths and the cam lobes still need direct evidence.
Select followers ↗Plan an inspection on the real car
- Identify the engine. Record its number and any visible replacement-part markings. This 1975 car may not retain every factory item.
- Open only for a real service job. Consult the correct Midget factory procedure for the fan, belt, pulley and timing cover before removal. Photograph the retaining nut and check socket access while assembled; the reported 155357 socket size is unverified on this car and its modeled thread size is an estimate. The CAD explosion distance is a viewing aid, not an access path.
- Record the cover fixings first. Photograph all perimeter holes and fasteners while fitted. Starting at the top dowel, label A through P clockwise using the checklist above. Count each head type, nut and lock washer; note brackets sharing a hole and compare with both catalogues.
- Capture the untouched layout. With the cover off, photograph its inner tensioner anchor and two rivets, then the timing marks, both sprockets, the oil thrower and its dish direction, all shims, key, chain, curved shoe, pin, two washers and split pins before turning or loosening anything.
- Index the parts. Record which face of the cam sprocket points outward and which two of its four holes take the bolts. Photograph the lockplate tabs before they are bent back.
- Inspect before ordering. Count the real teeth and chain pitches; measure the actual crank nose and gear bore. Check chain, tooth and tensioner wear using the factory method.
- Use the proper timing procedure. The Midget factory UK-specification operation 12.65.12 checks gear alignment with a straightedge and selective shims, aligns existing timing marks, and gives a separate note for new gears. Consult that full operation and the applicable North American procedure for this engine; do not copy the virtual gear phase or substitute the earlier Herald/Spitfire instructions.
Source and parts trail
| Record | What it establishes | What remains open |
|---|---|---|
| Midget factory specifications, p. 12 | Single chain, 0.375 in pitch, 62 pitches; tappet 20.30–20.32 × 44.45 mm; cam journal diameters and running clearances; 0.12–0.216 mm cam end float. | Center coordinates, gear tooth counts and this engine’s wear. |
| Midget 1500 internal-engine plate, p. 33 | Distinct cam retainer, two fixing bolts, chain, tensioner with pin/washer/split pin, both sprockets, cam lockplate and two sprocket bolts. | Exact fitted variants and dimensions. |
| Factory Midget 1500 parts plate B84, PDF p. 60 and 211126 gasket photo | Listed cover hardware totals 11 screws, one nut and 12 lock washers; the replacement gasket photo shows 14 holes. | Which catalogue-era fixing and cover variant is installed on this car. |
| Moss Europe Midget 1500 catalogue, printed p. 127 | Front-view clockwise A–P sequence for 14 positions: two dowels, five short pan-head screws, six longer hex-head screws, and one stud with washer and nut. | Exact hole coordinates and fitted hardware remain to be checked on the car. |
| Moss Europe Midget 1500 exploded drawing, printed p. 128 and 119390 part photo | A separate oil thrower sits ahead of the crank sprocket and behind the pulley; the photographed part is dished and notched. | Installed part, actual size, axial station and dish orientation. |
| Moss Europe 1500 tensioner items 45–50 and 42425 product photo | One curved shoe, one anchor plate, two rivets, one pin, two washers and two split pins are distinct pieces. | Installed shoe wear, plate position, retaining order and every physical dimension. |
| Used 217790U cover photo | Visible raised seal collar on a cover carrying the matching part number. | Collar outside diameter, projection, fitted cover identity and actual clearances. |
| 119389 crank gear listing and 838-205 cam gear photo | 35 mm listed crank bore; photo comparisons for teeth and cam fixing-hole arrangement. | Photo counts and profiles require confirmation on the fitted parts. |
| Midget factory timing chain and gears, operation 12.65.12 | UK-specification instructions for straightedge alignment, selective shims, gear/cam timing marks and a note for new gears. | Confirm the North American procedure and fitted gear variant; the earlier Herald/Spitfire manual is not a 1500 manual. |