An engine rebuild should be an integral part of any car restoration. Six cylinder, small block, or big block, the Camaro's engine is the life-blood of the machine, so it deserves first-class attention during your full-scale restoration.
As mentioned in a previous chapter, the planning for the engine rebuild should begin as soon as the engine is pulled from the subframe. Depending upon the situation, you could: A) Rebuild the engine yourself; B) Have someone else rebuild the engine for you; C) Purchase an already built engine assembly. If you're rebuilding the engine yourself, mount the engine on a stand (if you own one; if not, they can be rented or borrowed), disassemble the engine, inspect for wear, and deliver the major components (block, crank, heads, etc.) to a machine shop for hot tanking, boring, valve guides, balancing, and the like. If you're farming out the engine work, go ahead and deliver the engine to your rebuilder to avoid a possible delay in the future. When the time comes to reinstall the rebuilt engine into the restored Camaro, you don't want to stand around twiddling your thumbs while waiting for a mechanic to finish the engine rebuild.
Over the years, many early Camaro engines have been replaced by later model or different size powerplants. It's not unusual to find an original SS 350 Camaro powered by a later model 307, or a Z/28 fitted with a 427. Assuming that you're restoring your Camaro to original specifications, a non-original engine should be replaced by an original type and displacement motor. Fortunately, Chevrolet engines are abundant, except for some of the rarer versions like the Z/28's 302. Still, after locating a suitable engine, you'll probably have to rebuild, unless you're lucky enough to stumble across an already rebuilt assembly.
Above: Mr.October, aka famous professional baseball star Reggie Jackson demonstrated how to perform a proper burnout in a 1969 Camaro. This is an example of good tire smoke versus bad oil burning smoke coming out of your Camaro's tailpipes due to your engine being clapped out and put away wet.
When we first took delivery of our well-used and abused Z/28, we knew right away that the original 302 was limping on its last leg. Judging by the amount of smoke that streamed out of the tailpipes during acceleration, you could almost envision more oil entering the cylinders than gasoline. Amazingly, the Camaro still ran smoothly, and under heavy throttle, it could still stuff your spinal column into the seat back. But the ominous blue smoke that followed the Z/28 everywhere was a sure sign of impending doom.
Wear is an engine's greatest enemy. Once the cylinder walls and piston rings wear beyond a certain tolerance, the oil slips by the rings and is sucked into the combustion chambers where it burns along with the air/fuel mixture, hence the blue smoke from the exhausts. Also, worn valve guides allow the oil to sneak past the valve stems and into the combustion chambers.
With many older engines, you could have a combination of both, leading to excessive oil consumption and a strong hint that the engine needs a rebuild.
Besides the wear that can lead to oil consumption, Chevy V8's have another weakness: the camshaft lobes and lifters tend to wear faster than other components, leading to reduced valve lift and subsequent loss of power. On high performance engines with solid lifters, like our Z/28, the problem is accelerated if a previous owner failed to maintain the specified valve lash. In most cases, a camshaft and lifter replacement is required during a Chevy V-8 rebuild.
Above: The lead photo for Chapter 5 Engine Rebuild is a 1969 Camaro Z/28 302 V8 engine in a black 1969 Camaro Z28 (photo courtesy of RK Motors). The photo just above is self explanatory.
Anyone who has ever held a wrench can disassemble a Chevrolet engine, but knowing what to look for while taking the motor apart is an important key to successfully rebuilding an engine. First, strip off all the accessory items - alternator, power steering pump, brackets, etc. Then use a gear puller to remove the crankshaft vibration damper. On high performance Chevy small-blocks, don't forget to remove the fourth bolt that secures the damper to the crankshaft nose. Next, remove the carburetor and intake manifold, valve covers, water pump, and other parts. On a V-8, once the intake and valve covers are off, you'll get a better idea of the engine's overall condition by observing the amount of sludge inside the lifter valley and around valve springs.
While removing the rocker arms, inspect each individual arm for wear and discard if you notice score lines on the rocker arm seat or tip. Otherwise, keep each arm, ball, and nut together with a piece of wire. Pushrods and lifters should also be kept in their installed order if you plan to reuse them.
Remove the cylinder head bolts and pry the head away from the block by inserting a long wrench or ratchet handle into an intake port and lifting up. Then lift each head by hand (watch out, they're heavy) and place them on your workbench. If you own a spring compressor, you can disassemble the heads yourself; if not, the machine shop can do it for you. In nearly every instance, the heads will require a complete reconditioning, including valve guide replacement and valve seat reconditioning. Most machine shops disassemble the heads, clean them, recondition the seats, replace or knurl the guides, replace valves when necessary, and reassemble the heads. For high performance engines being rebuilt to stock specifications, a head rebuild by a competent machine shop is okay.
Above: 1969 302 V8 Chevrolet Camaro engine with dual four-barrel Holley cross ram aluminum intake (photo courtesy of Heritage Images Getty images)
After removing the oil pan and engine front cover, turn the short block over and inspect the bottom end. Before removing the pistons, be sure to stamp the rods and rod caps so they can be kept together during assembly. Mixing the rod caps can lead to premature rod bearing failure. As you remove each rod cap, slip a short length of rubber hose over the rod bolt threads to protect the crankshaft journals while you push the piston/rod assembly out of the block. Before forcing the piston out, check the ridge at the top of the cylinder bore. If the cylinder is well worn, or if the top of the cylinder has a heavy carbon build-up, or both, you may be forced to scrape the ridge down to size before pushing the piston out, especially if you plan to reuse the pistons.
As you remove each component from the bottom end, look for excessive wear patterns. Inspect piston skirt wear to see if a rod is bent or warped. Look for excessive scoring inside the cylinders, on the crankshaft journals, and inside the rod bearing area. Inspect the camshaft lobes and lifter bottoms for wear, and plan to replace if necessary.
When the engine is completely disassembled, deliver the major engine components - heads, block, crank, pistons, and rods -to the machine shop, usually a shop affiliated with a local automotive parts store. Here's where the rebuild gets expensive, but a competent machine shop is your best engine rebuilding ally. As part of the engine reconditioning process, the machine shop will clean the block, crank, and heads; inspect for cracks; rebuild the heads; polish or regrind the crankshaft; inspect the rods and pistons; bore the cylinders (if required); hone the cylinders; replace the rod bolts; and replace the cam bearings (if required), among other reconditioning procedures that vary from engine to engine and rebuilder to rebuilder. In most cases, the machine shop will check out the engine parts and inform you of the condition and work needed before proceeding. They may give you options, like whether or not to rebore depending upon how much piston slap noise you can tolerate.
Most machine shops clean blocks in a hot tank solution by soaking the block in the tank for several hours. This is definitely the best method, but the high-powered solution will erode the cam bearings within the block. So you might as well concede to paying the extra price for new cam bearings. If you're looking for a complete rebuild, it's best to start with an absolutely clean block and new cam bearings.
Above and below: Manifold Mending 101
What about balancing? With a stock rebuild, you don't need to worry so much about balancing the crankshaft, rod, and piston assemblies. If you're putting together a street machine or race engine, the situation is different. But Chevy high performance engines were balanced sufficiently from the factory, so you should be able to bolt your stock motor back together without going through the additional time and expense of a balancing job. During racing season especially, you could be looking at a six week to three month turn-around time.
Armed with the reconditioned components -clean block, rebored cylinders (along with brand new pistons), fresh cam bearings, polished crank, rebuilt heads, cleaned oil galleys, etc. -and the required engine rebuilding items -gasket set, new timing chain and gears, bearings and rings, assembly lube etc. -you're ready to start bolting the engine back together. Here's where a rebuilder's knowledge and experience pay off.
Regardless, whether you've rebuilt a hundred Chevy V-8s or if you're building your first, pick up a copy of How To Rebuild Your Small-Block Chevy or How To Rebuild Your Big-Block Chevy, both published by HP Books (Box 5367, Tucson, Arizona 85703). Since engine rebuilding deserves a book of its own, we won't go into the specific details here.
Like balancing, the term blueprinting has become an almost magical word among car people. Actually, blueprinting means putting the engine back together using factory-specified tolerances, so blueprinting is perfect for building an original motor. Factory tolerances can be found in either of the How To Rebuild books or a factory shop manual.
In the detailing chapter, we'll discuss the final detailing of the engine components. After all, in a restoration, the looks of the engine are just as important as the function.
Above: 1) Almost anyone can take an engine apart, but the key to rebuilding an engine is knowing what to look for as the engine is disassembled. 2) Engine tear-down requires some special tools, like this gear puller used to remove the balance damper.
Above: 3) After removing the valve covers, inspect the rocker arms for scoring or undue wear. Also, heavy oil deposits around the valve spring area indicates a past of infrequent oil changes. 4) The Z/28's high performance 302 is equipped with an oil baffle under the crank to keep the oil away from the spinning crankshaft. The baffle attaches to studs that double as the center main bearing cap bolts on the four-bolt main 302 blocks.
Above: 5) Like most well-used engines, our project car's small block contained a welI-worn timing gear and a stretched timing chain. Many replacement gears have nylon-coated teeth, but metal gears are best for performance applications. 6) On Chevrolet V8s, the camshaft and lifters should be closely inspected. Due to high valve spring pressures, the camshaft lobes and the lifter bottoms wear at a faster rate than other components.
Above: 7) Before removing the rod caps, be sure to stamp each cap and its mating rod. Mixing the caps and rods during reassembly could lead to premature bearing failure. 8) As the pistons are removed from the block, the cylinder bores can be inspected for wear. The size of the ridge at the top of each bore is a good indication of how much wear the bore has experienced.
Above: 9) Cleaning parts is a necessary engine rebuilding evil. A parts washer, like the professional unit shown, is nice, but not a requirement. You can always clean parts in a bucket filled with solvent. 10) At most machine shops, the engine block (and the crank and heads) is cleaned by soaking in a tank filled with a strong cleaning solution. By far the best method, the solution will erode cam bearings, so be prepared to pay the extra price of having the cam bearings replaced.
Above: 11) Thin cleaning brushes are used to clean out the oil galleys in the engine block. It's a time consuming procedure, but well worth the extra effort. 12) Machinists use a bore gauge to check the main bearing bores for roundness. If they are out-of-round, the block must be align-bored.
Above: 13) If cylinder walls are badly scored or worn, the block must be bored. And, of course, a bored block requires new pistons, which add to the rebuild costs.
Above: 14) Using a micrometer, machinists check crankshaft journals for wear and roundness. 15) For high performance use, the rod bolts should be replaced. Don't try this yourself with a hammer. For correct installation, the old bolts must be pressed out and the new bolts pressed in.
Above: 16) Balancing is a nice luxury, but not a necessity with a stock rebuild. 17) For correct head gasket sealing, the flatness of the heads must fall within certain tolerances. To check for warpage, a machinist's straight edge is laid diagonally across the head surface and measured with a .003-inch feeler gauge.
Above: 18) Milling the head surface will take care of minor warpage. Some machinists recommend milling .005-inch from any head to be used for high performance. The perfectly flat surface assures a good head gasket seal.
Above: 19) Head reconditioning always includes a valve seat resurfacing. Triple angle valve jobs are preferred for high performance duty. 20) The valves themselves are also reconditioned.
Above: 21) Bronze valve guides are tougher and more durable than regular guides or knurling. 22) Machinists use a micrometer to check for valve stem wear. If worn beyond a set tolerance, the valve must be replaced.
Above: 23) Here's our short block cast of players, cleaned and machined and ready to go back together. The heads, complete with a fresh valve job, bronze valve guides, and new Z/28 springs, have already been assembled by the machine shop. The new .030-over pistons were fit to their respective bores during the block boring operation. 24) All the necessary rebuilding gaskets can be purchased in one kit from most automotive parts stores. The kits include every gasket needed for a complete engine rebuild. Now that the Z/28's V8 engine is all rebuilt and back in fine tune, stay tuned for Chapter 6, where we'll be Putting On The Paint, same Classic Industries' www location, and coming soon!
Above: IROCs racing in the Unser Family Cup class (photo courtesy of the humble scribe)
Regardless of what generation Camaro you have, you'll find the vast majority of parts that you're looking for at Classic Industries. You can click here and shop online. You can also enhance your search by ordering a Camaro Parts & Accessories Catalog by clicking the button below and filling out the online form. Happy shopping, building, driving, racing, showing, and enjoying!