Crane Cams Responds to Your Questions on “Ask The Experts”


We have teamed up with several industry leading aftermarket automotive companies to address our reader’s questions in a monthly segment that we call “Ask the Experts.” Our first installment in this series features a company that really needs no introduction to speed enthusiasts, Crane Cams.

Founded in 1953, Crane Cams has been instrumental in supporting automotive enthusiasts and racers in every form of motorsports for over sixty years. Branching out from automotive Crane Cams began to develop components for the rapidly growing motorcycle market over 20 years ago. Today, Crane Cams valvetrain and ignition products are among the motorcycling industry’s most popular. 

In 1995 Crane introduced the automotive industry’s first digital ignition. This was followed by the industry’s first digital “drop in” points replacement, the industry’s first adjustable distributor with 27 advance curves, and the industry’s first distributor to employ fiber optics to send a trigger signal.

With one of the industry’s largest camshaft database, which exceeds 80,000 cam profiles, an impressive manufacturing capability, and an experienced tech staff, Crane Cams has volunteered to bring their expertise to help answer your questions.


Q: I was wondering what would suit the application for retarding my timing when I push the nitrous system I’m installing? Its just 100 shot “plate under the carb setup” on a 355 SBC ,mildly done, Vortec heads, 650 Holley carb, Edelbrock RPM intake. Any suggestions would be greatly appreciated. – From Erik Urban of Chatham, Ontario, Canada.

A: Crane Cams: Erik, You are correct, it is a very good idea to retard the spark event when the nitrous-oxide system is activated. The exact amount of spark retard that will be necessary to match your particular engine combination will need to be determined by you.

It will vary with such things as the compression ratio of the engine, the camshaft design, the installation position of the cam, the richness of the fuel mixture and even the altitude you will be operating the vehicle at. A Crane Cams HI-6 Series CD ignition (#6000-6440), with a PS92N coil (#730-0192), and using a TRC-2 Timing Retard Controller (#6000-6425) may be just what you’re looking for. The TRC-2 controller can be wired to come on at the same time the nitrous solenoids are activated. It has a knob that can be adjusted between zero and twenty degrees of spark retard. It can be mounted inside the car within reach of the driver where you can adjust the retard value.

Once you are satisfied with the setting you leave it in this position. The retard function will then be activated to this value each time the nitrous system in being used. (It also has an LED light that will come on when the retard mode is commanded).

Note: A general rule of thumb for nitrous systems, is approximately 1 ½° to 2° of timing per 50 HP of nitrous. So for a base line you would start with 3° to 4° less spark timing. Then experiment from there with your TRC-2 module adjustment.

Designed to work with engines from 10:1 to 14.5:1 compression ratios, nitrous, superchargers, or turbos. Made for street and racing use, they come with Crane's "Plug-n-Go" universal harness. The built-in rev limiter automatically drops cylinders in firing order to prevent fuel loading and is adjustable by increments of 100 from 600-9,900 rpm without any chips. Featuring solid-state construction that's immune to vibration and shock and an anodized heat-sink shell for reliability. Compatible with points and electronic ignitions and will work with 4, 6, and 8-cylinder engines with distributors.

How can I get a wider timing curve? My stroked 427 likes to start and idle @ 12° but then it will only advance up to around 33°. The car really runs @ 46° with no spark knock, but then it has to start around 19-21°. I have changed the springs and weights several time with little luck. The perfect curve for me would be from 12° to 46-48°. – From Tony Stapleton of Battle Ground, Washington.

Crane Cams “Pro Curve” street/strip distributor comes with 27 pre-programmed switch-selectable advance curves.

A: Crane Cams: Tony, You are asking for 34° to 36° of advance, starting at 12° base and ending up at 48° total. That may be difficult to obtain, but we might be able to get close with the Crane Cams “Pro Curve” street/strip distributor with adjustable advance curve. This might be the answer of your wishes. (But this unit is not a stand-alone system that fires the coil; it will require an ignition box to work).

This is an optically triggered distributor with a built-in electronic control module with 9 different advance curves and 3 different vacuum curves making a total of 27 possible settings. The advance curves are done electronically in the module so there are no advance weights or springs to deal with. The module has two dials that you use to select the curve you wish to use and a vacuum line can be installed. These curves are pre-determined and are already programmed into the module, with a total amount of advance of 24° from base timing. (But remember you are asking for 34° advance).

Since the Crane Cams distributor uses a highly accurate optical trigger device that allows you to set you timing event within +/- .5 degrees (that is ½ °), you no longer have to worry about the variance created by spark-scatter. You will be able to tune the spark timing to the sweet spot you have been looking for without having spark-scatter move you into detonation. You might be able to move your base timing up a little to 14°, that would give you 38° total.

Note: For more specific details on the shape of the advance cures you can go to our web-site There you will find the instruction sheets for the street / race unit. (On the web-site click on distributors, tech info, installation instructions, electronics, distributor, street/race. The rate of the advance curves are shown on the instruction sheet).

What advantages could someone expect to get out of a Crane Cams HI-6RL IGNITION on a stock or slightly modified daily driver ? – From Bill Hunter via Facebook.

A: Crane Cams: Bill, There are several different part numbers in the family of Crane Cams HI-6RL capacitive discharge ignitions. The RL refers to “rev-limited.” These ignition boxes are made for racing applications where the sanctioning body mandates specific maximum RPM limits. These are non-adjustable and the RPM is pre-set to match the rules. Although these RL boxes would certainly work for many street applications there are other HI-6 ignitions that would be more appropriate for a daily driver. (And if you didn’t have any RPM rule, these other ignitions are fully adjustable.)

The HI-6S ignition is tailored for streetable compression ratios up to 9.5:1.

All the Crane Cams capacitive discharge ignitions are high energy output for racing. Although these energy levels will work on the street, they are usually way more than is necessary for a daily driver. (The higher energy is required to fire engines with elevated cylinder pressure caused by increased compression ratios, turbo or super chargers, or nitrous-oxide systems and that are running at increased RPM.)

A more appropriate, stock compression ratio, street application would be the HI-6S series which is an “inductive” system (#6000-6300). This HI-6S ignition is tailored for streetable compression ratios up to 9.5:1. These inductive ignition systems have a longer duration spark which provides a better burn rate to the combustion chamber. You get increased low in torque and better mileage due to the thorough burning of the fuel. These inductive ignitions operate best in the RPM range of a “real daily driver” vehicle. The HI-6S has built-in adjustable rev-limiter that you can set at your desired limit. The matching coil would be the either the canister style PS60 (#730-0060) or the e-core design LX9I coil (#730-0891).

But if you have a racecar high cylinder pressure engine, that just happens to be on the street, then you should use the capacity discharge ignition.

Note: Explanation of the HI-6RL family of “rev-limited” ignitions. Here are the part numbers and the max RPM that the box is pre-set for: #6000-6463 (6,300 RPM), #6000-6474 (7,400 RPM), #6000-6476 (7,600 RPM), #6000-6478 (7,800 RPM), #6000-6480 (8,000 RPM) and #6000-6484 (8,400 RPM).

When running an aftermarket cam what’s the best way to know that your timing is set to the best place and ensure there is no detonation? – From Cody Babineau of Saint Stephen, New Brunswick.

Adjustable timing controllers are one of the tools that can be used to find where the engine runs the best without detonation.

A: Crane Cams: Cody, There are several factors that can effect detonation. It is the total combination of the component parts used to build the engine, the tuning of the engine, the octane rating on the fuel being used and the application of the vehicle. There is no set answer to your question; it all depends on the specific circumstances that you are dealing with. The old saying is, “You want to run as much spark advance as you can in avoidance of detonation/spark knock.” That doesn’t really give you a direct answer, but it provides a guide line.

You will have to experiment with your set-up to see what it likes, or how much timing it can tolerate. You should start at a “stock” or conservative spark advance setting then test drive the vehicle under the conditions that you will normally be using it. (For example, at the appropriate engine temperature, using your normal fuel and under the load that the engine would most likely see.)

Then you will add spark advance to the engine and test drive it again. Keep this up until you witness detonation/spark knock. Back the timing down a couple of degrees and leave it at this point.

There may be several other tuning tools you can use, such as adjustable spark advance mechanisms in the distributor, an adjustable vacuum advance system, as well as adjusting base timing by rotating the distributor housing in the engine. What you are looking for is the place the engine runs its best without the negative (and dangerous) effect of detonation. This maximum limit will be different for each engine and application. It must be individually tested to arrive at this point.

Q: I have a 2004 GTO engine swapped into a 1993 GMC Typhoon with a 4l80-e transmission. I was thinking about improving the ignition system. It is currently all stock (ignition system). What would be the best thing to do on a budget? Coils? wires? both? – From Norm Smith of Winnipeg, Manitoba, Canada.

"Generally speaking, the replacing of the coils and plug wires with new parts is a very good idea."

A: Crane Cams: Norm, From your description this should be a 5.7L LS Series engine that has an ECU computer controlled system. This year engine should be computer controlled which handles the ignition firing events relying on internal engine sensors from the camshaft and crankshaft to determine when the firing event should take place. It should be using the “coil on plug” feature (with each spark plug having its own coil).

The only aftermarket products you could possibly use, considering the budget, would be a set of upgraded spark plug wires and upgraded coils. If this is a stock engine the increased output of the coil and plug wires would be unlikely to show any major power gains, but generally speaking, the replacing of the coils and plug wires with new parts is a very good idea.

Up Next

Chevy Hardcore wants to thank Crane Cams and their technical professionals for taking the time to answer our reader’s questions. It’s rare that enthusiasts have this personal one-on-one time to get direct answers from the professionals that design high performance components. We are thrilled that these questions are being addressed in a public forum where other automotive enthusiasts can see the responses and add to their personal knowledge base.

Next month we will continue with our “Ask the Expert” monthly column with our guests from Holley Performance Products. Questions can be submitted via email at or on our facebook fan site at 

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About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
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