Cheap Aluminum Heads Put To The Test: Are They Worth It?

Jim’s Automotive Machine Shop went hands-on with a set of bargain small-block Chevy aluminum heads to answer a question many engine builders have wondered about: are the cheap aluminum heads found online actually usable, or are they a waste of time?

The heads in this recap were bare castings advertised with 2.020-inch intake valves, 1.600-inch exhaust valves, a 68cc combustion chamber, 200cc intake runners, and bronze valve guides. Right out of the box, the basic machining looked better than expected. The head gasket surface was checked straight with a straightedge; the ports and chambers didn’t show obvious sharp edges, and the valve seats featured a clean three-angle cut.

Where The Problems Showed Up

The first real issue with these cheap aluminum heads appeared at the spark plug threads, which extended into the combustion chamber. Jim fabricated a simple cutting tool using a modified spark plug as a guide, then trimmed the exposed threads and chased them to remove burrs. This ensured proper spark plug installation and prevented carbon buildup that could cause removal issues later.

Seat location revealed the greatest concern. The intake valve contact was centered correctly on the valve face, but the exhaust valve contact was positioned too far inboard. The exhaust seat was not contacting the full valve face as desired, which required recutting the seats to correct the angle and placement.

Machine Work That Made Them Usable

After recutting, valve depth was checked for consistency across cylinders, and runout measurements came in under .001-inch, which Jim considered acceptable. Combustion chamber volume was also verified, checking in at approximately 68cc, matching the advertised specification.

During final assembly, the installed height required attention. Offset keepers and shims were used to achieve proper spring height and maintain moderate seat pressure suitable for a flat-tappet camshaft. A vacuum test confirmed strong sealing on both intake and exhaust ports, with a reminder to seal rocker arm studs that break into the intake runners.

The takeaway was clear: these heads are not ready to bolt on out of the box, but with proper machine work and careful assembly, they can be made usable for budget-minded small-block Chevy builds.