Crane Cams Tech Support (Part 1)

May 22, 2009

We managed to glean a host of informative technical tips from the boys at Crane Cams.These tips cover a range of subjects from distributor gear wear to V-Twin motorcycle cams, and we think you’ll find them helpful.

Distributor Gear Wear:

It has come to the attention of Crane’s Tech and Customer Service departments that premature cam distributor gear wear and breakage can occur. The two practices that can cause gear wear are running a high-volume or high-pressure oil pump or reusing an already worn or damaged distributor gear with a new cam (or vice versa). In this case the distributor gear or cam gear has worn into a pattern and may not mesh with the new part. This can cause breakage and/or continue to prematurely wear out the gear.

“Good” vs. “Rough” Idle:

What does “good idle” and “rough idle” actually mean? Compared with what? Smooth and good idle represents a stock or near-stock idle, 600-800 RPM with a high vacuum signal. Rougher idles are higher idle speed, 850-1200 RPM, lower vacuum signal. The engine actually seems to shake (rough) with a rough idle camshaft.

Pushrod Length and Rocker Geometry:

What’s the best way to check whether this is too long or too short? Here are some do’s and don’ts. Do use Crane’s adjustable checking pushrods. Don’t use other dummy rocker arm fixtures (on the head stud checker). Do set the lash by hand at zero. Do blue the end of the valve stem. Do run the engine through two intake and exhaust cycles while observing the tracking of the roller wheel. Do adjust the checking pushrod in or out until you achieve the exact equal tracking across the top of the valve stem. If you are checking a hydraulic engine, use a solid lifter during this procedure.

V-Twin Motorcycle Cams:

Single overhead cam, roller follower, air cooled, 1000cc V-Twin? Sounds like one of the latest state-of-the-art Metric cruiser offerings? No, Crane is currently producing an exclusive batch of camshafts for the 1914 Cyclone Track Racer motorcycle engines. For a short time, these engines dominated board racing in the shorter duration events, with Indian and Harley-Davidson as their closest competition. The leading restorer of these unique bikes (of which only a handful exist in the world), Stephen Wright, depends on Crane Cams to ensure that only the highest quality camshafts are used in his masterpieces.


For vehicles with daytime running lights, you will need to set the parking brake before turning the key to the “ON” position. This will turn the DRL off. If this is not done, it may interfere with the programming.


When, and if, it happens to a Harley, it can be very expensive to deal with and usually can be prevented easily. A Harley bike has an inductive-type ignition system that will fire when the current in the primary of the coil is switched off. If your battery is low during cranking, the current in the coil can go low enough to enable it to fire the spark plug. If this occurs with the piston in the wrong position, kickback can occur. This usually results in broken gears and a “hurt wallet.” Make sure your battery is maintained and that your starter can turn your motor over without starving the ignition system. To help eliminate a kickback condition, the Crane Cams ignition modules allow the motor to turn over for two revs before the ignition turns on. Another engineering perk to help you.

Regrinding Used Camshafts:

In those cases where Crane doesn’t offer an outright cam core for your particular application, the company can probably regrind your good used camshaft. Cams that do not have severely worn lobes can usually be reground. However, many folks don’t check for worn distributor drive gears or fuel pump lobes before forwarding them to Crane. Also, the cam’s journals should be in good shape. Crane can’t repair worn journals, distributor gears or fuel pump lobes, so be sure to check your camshaft thoroughly before considering it for regrinding purposes. Severely bent cams (over .030″) also aren’t good candidates for regrinding.

Mechanical Lifters Camshafts:

When using mechanical lifter camshafts in Ford FE 352-428 V-8 engines, Crane recommends its 99256-16 shell-type mechanical lifters (along with their 34642-16 pushrods); however these lifters are now no longer available. The 99257-16 standard-style mechanical lifters are now advised, along with Crane’s 34645-16 pushrods. These can be used with either Crane’s 34772-16 ductile iron adjustable rocker arms or the company’s new 34790-16 adjustable aluminum rocker arm kit.

Springs for Aftermarket Heads:

If you’re purchasing aftermarket heads complete, decide which cam you’re planning to use so you use the correct spring pressures. Most consumers look at the maximum lift that the springs can handle and don’t pay as much attention to the seat and open pressures. If you’re planning to use a flat tappet cam, Crane suggests you purchase the heads bare, then outfit the heads with the required springs so prevent wiping out the cam due to too much spring pressure for the flat tappet cams.

V.O.E.S. (Vacuum Operated Electric Switch) for Harley Davidson:

The V.O.E.S. is a vacuum advance, not a retard unit. It’s designed to advance the ignition timing when the engine isn’t under load. All dressers should advance at 5.5″ to 6.0″ of manifold vacuum; Softails and Dyna Glides around 3.5″ to 4.5″. Sportsters should advance at 3.0″. On all motors that have increased compression ratio or a performance cam is installed, set V.O.E.S. at 5.5″.

American Motors/Jeep and Chrysler/Dodge/Plymouth Mechanical Lifters:

The 99260-12 and 99260-16 mechanical lifters for the American Motors/Jeep 199-258 I6 and 290-401 V-8 engines, along with the Chrysler-Dodge-Plymouth 273-360 V-8’s are now available. These had been in short supply for a couple of years, but are now in stock. These are .904″ diameter, capable of carrying oil up the pushrods, and can also be used in non-pushrod oiling applications. Current suggested resale prices are $125.76 for the 99260-16 and $94.32 for the 99260-12. Standard discounts apply.

What Goes In Must Get Out!:

One of the biggest performance mistakes many street performance enthusiasts make is to not provide enough exhaust capacity for the horsepower level they are trying to achieve. Installing a bigger cam, aftermarket cylinder heads and a high-flow intake system is of little use if you can’t get the air out of the engine as well. For maximum power and driving pleasure, tubular exhaust headers are recommended for any camshafts with durations at .050, lifter rise of 210 degrees or greater. Failure to provide adequate exhaust with large camshafts results in poor idle quality, hesitation on acceleration, part throttle surging, poor power brake performance, etc. Due to design considerations, some body styles (such as the 1982-1991 GM F-bodies) have extremely limited space for enlarging the exhaust. You should consider this limitation when selecting a camshaft for a vehicle. Less power is lost by slightly undercamming rather than overcamming.

Hydraulic Roller Tappets:

If you’re going to install a performance camshaft with higher valve lift in your 8.1L Chevy big-block engine, make sure that you check your hydraulic roller tappets. If you go too low in the lifter bore, they could bind or fall out of the original hold-down plate, causing severe damage to the engine and valve train. To solve this problem, Crane Cams has developed a taller lifter, which is made for higher valve lift and will work with the factory hold-down assembly. Use Crane Cams hydraulic roller tappet Part #26535-16 for that application.

New Spring Application:

For anyone putting Chevy Vortex heads on early 350 V-8s, Crane has a new spring and retainer for these heads. This is a dual spring that will fit the stock spring pockets with no machining. (Note: the valve guides must be trimmed to .531″ diameter and the appropriate valve guide seal used).

Part Numbers:


Retainers#99975-16 (new multi-fit) 5/16″

Locks#99093-1 11/32″


The valve stem locks are our multi-fit style and are available in +/- .50 heights. You will need a spring shim on the bottom of the spring when installing. This can be used with hydraulic flat tappet or roller cams. Also, remember to use our Gold Rockers (#11750-16 1.5 ratio, #11759-16 1.6 ratio) to complete the change.

Generation IV, V, and VI Big Block Chevy:

The Gen IV engines all come from the factory with flat tappet cams (1967-1995). Gen V engines still use a flat tappet cam and started using a 360′ crank seal, single row timing chain and gear set and non-adjustable rockers (’95). Some Gen V engines were made with hydraulic rollers for marine applications only. There is no core for these hydraulic roller cams, so a Gen IV Retrofit hydraulic roller cam must be used as a replacement, along with a double roller, timing chain and gear set with an Imco (909-592-6162) timing cover to match. The Gen VI engine comes as a hydraulic roller (1996-2000). This engine also uses a single-row timing chain and gear set, 360′ crank seal and non-adjustable rocker arms.