The shop manual

The CLASSIC PARTS GARAGE counter9 min readAug 30, 2026

Why your flat-tappet camshaft went flat, and the oil that prevents it

Modern oil had the zinc taken out of it to protect catalytic converters your 1969 truck does not have. Here is what that does to a flat-tappet camshaft, and how to avoid it.

SHEET 006 · FIGURE 01
WHY YOUR FLAT-TAPPET CAMSHAFT WENT FLAT, A

Converting a 1967–1972 C10 to front disc brakes

The full job on an Action Line truck, including the master cylinder question everybody gets wrong and the proportioning valve everybody skips.

11 minAug 23, 2026

Square-body buyer's guide: what rust actually costs

Six failure points that decide whether a 1973–1987 C10 is a project or a money pit, and how to check each one in the ten minutes you get before committing.

10 minAug 16, 2026

Reproduction, NOS or used: choosing parts for a driver versus a show car

The three ways to buy a classic part, what each actually costs you, and why the right answer changes completely depending on what you are building.

8 minAug 9, 2026

Reading GM casting numbers and date codes

How to work out what block, head or manifold you actually have — and whether it is the one that left the factory in your car.

7 minAug 2, 2026

Install guidesEasy

Points to electronic ignition without changing how it looks

Fitting a Pertronix module inside the original distributor: the coil question, the polarity trap, and how to keep the option of putting it back.

7 minJul 26, 2026

Install guidesHard

Replacing cab corners and rocker panels without ruining the door gaps

Cab corners are the most commonly botched repair on a classic truck. The welding is the easy part. Keeping the cab in shape while you cut the bottom out of it is the job.

12 minJul 19, 2026

Install guidesEasy

Fitting a complete weatherstrip kit without tearing it

New rubber is the cheapest thing you can do that makes a fifty-year-old vehicle feel finished. It is also easy to ruin in the first ten minutes by stretching it.

8 minJul 12, 2026

Fitting and tuning a 600 CFM carburettor on a small block

Bolting it on takes an hour. The tuning is where people give up and conclude the carburettor is faulty, when almost always it is the ignition timing.

11 minJul 5, 2026

Hanging a reproduction fender so the gaps look factory

Reproduction sheet metal fits, but it does not self-align. The difference between a good result and an obviously repaired one is entirely in the setup.

9 minJun 28, 2026

Rebuilding the SU-type carburettors on a Datsun L-series six

Round-top SUs are simple, rebuildable and much misunderstood. Most that get replaced with a downdraught conversion were only worn in two places.

10 minJun 21, 2026

Replacing a fuel tank and sending unit, and getting the gauge to read right

A tank swap is straightforward. The gauge reading correctly afterwards is not automatic, and the reason is almost always ohms.

9 minJun 14, 2026

Early Bronco buyer's guide: where they rot and what it costs

Values have climbed far enough that a rusty Bronco now costs real money. Here is where to look before you agree a price, and what the bad news is worth.

11 minJun 7, 2026

Datsun 240Z buyer's guide: the six places rust hides

The S30 is a monocoque, which changes everything about how you inspect it. There is no frame to fall back on — the rusty panel is the structure.

10 minMay 31, 2026

Copper-brass or aluminium: choosing a radiator for a classic

Aluminium is not automatically better and copper-brass is not automatically correct. The right answer depends on what the vehicle is for.

8 minMay 24, 2026

Carburettor sizing: why a bigger carburettor usually makes less power

The 750 looks like the serious choice. On a stock 350 it will be slower everywhere you actually drive, and here is the physics of why.

7 minMay 17, 2026

Wheel offset, backspacing and bolt pattern, explained properly

Three numbers decide whether a wheel fits, and two of them measure the same thing from different directions. Get one wrong and it rubs, or it does not go on at all.

8 minMay 10, 2026

Why your classic runs hot, in the order worth checking

Overheating is nearly always cheap to fix and rarely the radiator. Work through it in this order and you will usually find it in the first three steps.

10 minMay 3, 2026

Tracing electrical faults on a fifty-year-old harness

Nearly every intermittent electrical fault on an old vehicle is a ground, a connector, or a bulkhead pass-through. Almost none of them are the component.

11 minApr 26, 2026

Your gauges are lying: grounds, senders and instrument voltage

If every gauge reads wrong together, it is one fault, not four. If one reads wrong, it is that circuit. That distinction saves an afternoon.

8 minApr 19, 2026