Does My Engine Need An Overhaul?
Just because your classic car is old doesn't mean the engine needs a rebuild. Minor symptoms by themselves may be repairable without pulling out the motor and doing a complete overhaul.
To determine what is the best course of action, consider the following engine conditions and symptoms:
High Mileage
One of the more common reasons for an engine overhaul is excessive mileage. Today's modern car engines can run for 200k+ miles, but on a 1970s or older model, anything over 100k is considered high mileage.
Poor fuel mileage is another reason. It might be hard to tell on a large V8, but anything below 10 mpg on the highway is probably a good indicator the engine is old and tired.
Excessive Oil Consumption
Back in the day, I had a 1971 Camaro that burned a quart of oil every 250 miles. Turns out a piston ring was broken, but it still ran OK. Anything more than a quart every 500 miles tells you something is wrong.
Sometimes you don't have a clear indicator of whether or not an engine needs a rebuild, but if you have several minor issues (for instance, bad mileage and oil consumption), it may a good idea to rebuild the entire engine.
Poor Engine Compression
Readings of 30-35 psi lower than specs indicates worn rings or valves (or both). If one or more cylinders read considerably lower than the highest one, those cylinders are most worn.
Engine Testing Tools
For checking engine compression, you need a compression tester, which consists of a gauge and a hose.
Pictured: hand-held compression tester with quick-release.
After threading in one end of the hose into a spark plug hole, the engine is cranked (with ignition disconnected). The gauge has a stop valve that holds the highest reading until it's released.
It's always best to check compression when the engine is warm, but can still be performed if it doesn't run. It just needs to be able to crank at normal speed.
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Can I Rebuild An Engine Myself?
If you decide that a complete overhaul is necessary, you may find yourself asking, "Can I rebuild an engine myself?"
Here are some points to consider.
Work Space - You will need a dedicated place to work in, preferably clean, well-lit, and secure. This is not so easy in a family garage. You'll be leaving various engine parts around, so try to keep people out as best you can without offending them!
Mechanical Ability - Some people are naturally mechanically inclined. My guess is that if you're reading this article, you are.
Tools Needed
Aside from basic hand tools, you'll be needing a piston ring installer, a torque wrench, dial caliper, feeler gauge, harmonic balancer remover and installer, and possibly others.
Read: Tools Needed For An Engine Build
There's a few outside sources needed while restoring your engine, which include a parts supplier, a tool supplier, and a machine shop.
Shop Manual - Don't rely on the internet. A factory shop manual for your make and model car is invaluable.
Machine Shop - Without expensive, dedicated equipment and a lot of experience, you'll need to farm out steps such as block boring, crank and rod balancing, and cylinder head rebuilding.
Parts Supplier - It seems like good parts stores and good parts guys are becoming a thing of the past. The internet is often an only choice for certain parts.
If you're removing the engine, you'll need to rent or buy an engine hoist. And you'll need an engine stand.
Rebuilding a complete engine requires patience. There are many small steps in engine rebuilding, each as important as the others. It could become long and complex, particularly if parts are hard to find. You need common sense and you need patience.
Take Nothing For Granted
A complete overhaul requires measuring and re-measuring, assembly, disassembly, and reassembly. Make sure everything is right before continuing to the next step.
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Crate Engines (Short Block vs Long Block)
As an alternative to rebuilding yours, there are fresh-built crate engines. A short-block will include a pre-assembled block with connecting rods, pistons and crankshaft.
A long-block gives you a short-block plus cylinder heads, valvetrain, and engine tin, which usually includes a timing chain cover, valve cover(s), and oil pan.
Here is a link to Ford, Chevy, and Mopar crate engines sold by Summit.
NOTE: Most crate motors do not include manifolds, accessories, and wiring harnesses.
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