Andrews A Cam: Harley-Davidson V-Twin Specs, Performance, and Installation
The Andrews A cam is one of the most legendary, time-tested performance camshaft grinds ever engineered for Harley-Davidson Big Twin motorcycles. Manufactured by Andrews Products in the United States, the "A" grind earned iconic status among Panhead and Shovelhead riders for its ability to awaken dormant low-to-midrange torque without sacrificing smooth highway cruising. Designed as a true bolt-in camshaft that operates harmoniously with stock valve springs and hydraulic or solid lifters, the Andrews A cam delivers a broader powerband, crisper throttle response, and that unmistakable rhythmic idle cadence coveted by vintage motorcycle purists.
V-Twin Camshaft Geometry, Duration, Lift, and Power Delivery Curves
The design philosophy behind the Andrews A grind focuses on optimizing cylinder filling within the street-usable RPM range. Factory original Harley-Davidson H-grind cams from the AMF era were notoriously mild, choked down by conservative emissions mandates and restrictive timing that left 74 and 80 cubic inch Shovelheads feeling sluggish below 3,500 RPM. The Andrews A cam increases valve lift to 0.450 inches across both intake and exhaust valves while maintaining moderate duration of 244 degrees, dramatically enhancing volumetric efficiency between 2,000 and 5,500 RPM.
Beyond raw horsepower gains, the Andrews A cam is celebrated for its mechanical friendliness toward stock valvetrains. Because the lift does not exceed the critical 0.460-inch threshold on Big Twin heads, it eliminates the need to machine valve spring collars or shorten valve guides when installed on unmodified cylinder heads. Whether piloting a stripped-down kickstart chopper, a daily ridden Super Glide, or an FLH King of the Highway loaded with saddlebags, this camshaft delivers robust roll-on passing power without inducing valvetrain rattle or premature component wear.
Carefully examining valve opening and closing angles allows engine builders to verify cylinder pressure retention and valvetrain timing. Review the official manufacturer camshaft specifications listed below.
| Specification Parameter | Intake Valve Value | Exhaust Valve Value | Measurement Benchmark | Performance Characteristic |
|---|---|---|---|---|
| Valve Lift (Big Twin) | 0.450 inches (11.43 mm) | 0.450 inches (11.43 mm) | With stock 1.5:1 rocker arms | Optimized for stock valve spring travel |
| Duration at .053 in Lift | 244 degrees | 244 degrees | Industry standard lifter lift | Broad usable torque without high-RPM float |
| Valve Opening Angle | 19 degrees BTDC (Before Top) | 43 degrees BBDC (Before Bottom) | Crankshaft rotation degrees | Rapid cylinder scavenging and fill initiation |
| Valve Closing Angle | 45 degrees ABDC (After Bottom) | 21 degrees ATDC (After Top) | Crankshaft rotation degrees | Traps dynamic cylinder pressure effectively |
| Valve Overlap Duration | 40 degrees total | 40 degrees total | Intake/Exhaust overlap angle | Clean idle stability with crisp throttle punch |
| Recommended RPM Band | 2,000 to 5,500 RPM | 2,000 to 5,500 RPM | Normal street operating range | Ideal for daily street riding and touring |
Engine Compatibility for Shovelhead, Panhead, and Sportster Applications
The engineering pedigree of the Andrews A cam has made it a cornerstone of Harley-Davidson V-Twin customization for over four decades. When Harley-Davidson transitioned from Panhead to Shovelhead production, riders sought camshaft upgrades that would deliver noticeable acceleration without demanding radical cylinder head work. The A grind struck the ideal balance, generating immediate power off idle while allowing the bike to pull hard up through third and fourth gears on two-lane highways.
Proper installation of an Andrews A cam begins with checking gear lash between the cam gear and the engine pinion gear. Harley-Davidson manufactured pinion gears in seven distinct color-coded pitch diameters to compensate for subtle casting variances in engine crankcases. When replacing the camshaft, builders must measure backlash using a dial indicator or ensure the existing pinion gear color code meshes smoothly with the Andrews cam without binding or excessive play, preventing irritating gear whine or catastrophic gear tooth wear.
Selecting the proper cam grind depends on engine displacement, compression ratio, and riding style. The table below compares the A cam to alternative Andrews Shovelhead profiles.
| Cam Profile Model | Valve Lift (Int / Exh) | Duration @ .053 in | Recommended Compression | Primary Riding Application |
|---|---|---|---|---|
| Andrews A Cam | 0.450 in / 0.450 in | 244 deg / 244 deg | Stock 8.0:1 to 9.0:1 | Street cruising, touring, excellent low-end torque |
| Andrews B Cam | 0.470 in / 0.470 in | 248 deg / 248 deg | 8.5:1 to 9.5:1 (Spring mod) | High-speed highway cruising and mid-range roll-on |
| Andrews C Cam | 0.500 in / 0.500 in | 256 deg / 256 deg | 9.5:1 and Higher (Extensive mods) | Modified strokers, aggressive street performance |
| Andrews J Cam | 0.405 in / 0.405 in | 236 deg / 236 deg | Stock 7.4:1 to 8.0:1 | Mild replacement cam for heavy touring sidecars |
| Andrews EV27 (Evolution) | 0.495 in / 0.495 in | 236 deg / 240 deg | Stock Evo 8.5:1 to 9.5:1 | Evo counterpart to the legendary A-cam profile |
Installation Protocols, Pinion Gear Sizing, and Valvetrain Clearance Checks
Valvetrain clearance verification remains mandatory even when installing a bolt-in camshaft like the Andrews A. While the 0.450-inch lift is engineered to clear stock Harley-Davidson valve guides, aftermarket replacement heads, resurfaced rocker boxes, or previous valve jobs may have altered spring heights. Builders must confirm that at least 0.060 inches of clearance exists between the top valve spring collar and the valve guide boss at full valve lift, and verify that valve-to-piston clearance measures no less than 0.080 inches on the intake stroke.
Carburetor jetting and ignition timing should be fine-tuned following cam installation to extract maximum performance. With increased valve lift and duration, the engine draws significantly more air-fuel mixture during the intake stroke. Re-jetting a Keihin butterfly, S&S Super E, or Bendix carburetor by increasing the intermediate and main jet sizes prevents lean backfiring through the air cleaner and delivers smooth, responsive acceleration across the entire rev range.
For vintage motorcycle enthusiasts restoring or upgrading a 1948-1984 Big Twin, the Andrews A cam represents an unbeatable blend of American-made precision and vintage reliability. Its ability to work seamlessly with stock pushrods, stock valve springs, and modest compression ratios ensures that riders enjoy modern mechanical performance while honoring the timeless soul and thunder of classic American iron.
How to Install and Time an Andrews A Camshaft in a Harley Shovelhead
Follow this technical procedure to remove the stock cam, verify gear lash, align timing marks, and check clearances when installing an Andrews A cam.
Relieve Valvetrain Tension and Remove Rocker Covers
Remove the spark plugs, rotate the engine to top dead center, collapse the pushrod covers, and loosen the pushrods to remove all mechanical tension from the lifters.
Remove the Cam Cone Nosecone Cover
Unbolt the outer ignition timer cover, remove the points or electronic ignition pickup plate, and unbolt the right-side cam cover to expose the geartrain.
Inspect Pinion Gear and Remove Stock Camshaft
Carefully slide the existing camshaft out of the inner Torrington needle bearing, inspect the bearing rollers for pitting, and verify the pinion gear color code.
Align Timing Marks on the Andrews A Cam
Lubricate the Andrews A cam lobes with assembly lube, align the cam gear timing punch mark precisely with the pinion gear and breather gear timing marks, and slide the cam into place.
Check Endplay and Reinstall Cam Cover
Verify camshaft endplay measures between 0.005 and 0.015 inches using shims, install a new cam cover gasket, torque cover bolts to factory spec, and adjust pushrods to zero lash.
Frequently Asked Questions (8 Questions Answered)
Q1: Is the Andrews A cam a bolt-in camshaft?
Yes, the Andrews A cam is a true bolt-in grind designed to work with stock Harley-Davidson valve springs, guides, and pushrods on Panhead and Shovelhead engines.
Q2: What is the lift and duration of the Andrews A cam?
The Andrews A cam features 0.450 inches of valve lift on both intake and exhaust, with a duration of 244 degrees measured at .053 inches of lifter lift.
Q3: Can I run an Andrews A cam with hydraulic lifters?
Yes, the Andrews A cam is engineered to operate smoothly with either hydraulic lifter tappets or solid lifter pushrods, making it highly versatile for street setups.
Q4: What RPM range does the Andrews A cam perform best in?
The A-cam produces optimal torque and horsepower between 2,000 and 5,500 RPM, providing excellent low-end roll-on acceleration and highway passing punch.
Q5: Do I need to replace my inner cam needle bearing when changing cams?
Yes, engine builders strongly recommend installing a fresh full-complement Torrington B-138 needle bearing whenever swapping camshafts on Big Twin engines.
Q6: What is the difference between an Andrews A cam and a B cam?
The A cam has 0.450 lift and 244 duration for street low-end torque, while the B cam has 0.470 lift and 248 duration, shifting the powerband higher for fast highway cruising.
Q7: Will an Andrews A cam fit an Evolution (Evo) engine?
No, the classic A cam is designed specifically for generator and alternator Big Twins (Panhead/Shovelhead); the equivalent popular grind for Evolution engines is the Andrews EV27.
Q8: Do I need to rejet my carburetor after installing an Andrews A cam?
Yes, because the camshaft improves cylinder breathing and air intake volume, slightly increasing intermediate and main jet sizes is recommended to avoid running lean.
Final Thoughts & Key Takeaways
In conclusion, understanding andrews a cam: harley-davidson v-twin specs, performance, and installation provides essential clarity, practical strategies, and actionable advice. By incorporating these foundational insights, adhering to verified safety guidelines, and following structured best practices, you ensure reliable, long-term outcomes while preventing common mistakes. Stay informed, consult certified professionals when needed, and maintain consistent quality care.