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Cummins push tube timing is essential for achieving accurate injector performance across iconic diesel platforms like the N14, 855 Big Cam, and KTA series. If you’re working on a Cummins engine, mastering Cummins push tube timing is crucial for maximizing power and efficiency. This detailed guide explains exactly how to set Cummins push tube timing step-by-step—covering inspection, piston travel measurement, and cam follower adjustment to ensure optimal fuel delivery and engine efficiency.

What is Cummins Push Tube Timing?

Cummins push tube timing refers to the calibration of injector push rod travel relative to piston position. It ensures that fuel injection occurs at the precise moment during the compression stroke, maximizing power, fuel efficiency, and emissions control.

Cummins Platforms That Require Push Tube Timing

Push tube timing is commonly required for the following Cummins platforms:

• N14 (CELECT & CELECT Plus)
• 855 Small Cam & Big Cam
• NTC350, NTC400
• KTA19, KTA38, KTA50
• VTA, VT-225, V-504, VT-555
• L10, M11
• K19, V903 (uses cam key changes instead of gasket stacking)

Step-by-Step Procedure for Setting Cummins Push Tube Timing

Step 1: Inspect Push Rods

Inspect push rods. Make sure each push rod has a “bell” like sound when tapping on something solid. This ensures they are not filled with dried up oil inside of the push rod. Next roll the push rod on a flat surface to make sure the pushrod is not bent.

Step 2: Seat the Camshaft

Ensure the cam is pushed back tight to the cam thrust.

Step 3: Install Cam Follower Box

Start off with a permaseal gasket for the innermost gasket with the permaseal facing the block. It is best to start with the same thickness of gaskets that was originally pulled from the cam follower box before the engine was torn down. This typically will get you in the ballpark of the spec you wish to be at. 

Step 4: Inspect and Install Cam Followers

Inspect the cam follower to ensure nothing is wrong with them. Then go ahead and install them on the engine. Be sure to not “roll” any of the thinner gaskets in your stack of gaskets. Start all the bolts by hand and then torque them to 35 Foot lbs in a inner to outer pattern

Step 5: Install Push Tube Timing Tool

Install the push tube timing tool into the injector hole and install one injector push tube. Ensure the push tube is straight up and down and not being interfered with by the head gasket. Note: before getting started it is a good idea to ensure your gear timing is correct between the crankshaft gear and the cam gear. If the camshaft was replaced, always pay attention to the cam key and what direction the arrow is facing. It is very important to go back with the same key in the same direction otherwise the push tube timing will not be able to be put into spec correctly. 

Step 6: Find Top Dead Center (TDC)

Find top dead center of the cylinder you are checking. Zero your piston indicator, indicating where true top dead center is. Continue to turn the engine in the direction of engine rotation and watch the piston control rod drop. When the piston is toward the bottom of the travel the pushrod gauge should come to a stop. If the pushrod gauge continues to travel down and does not stop you are on the wrong stroke for the piston and need to rotate the engine 360 degrees and start the process over in step 6. When the piston gauge reaches bottom and the pushrod indicator stops moving, go ahead and “zero” the camshaft gauge.

Step 7: Measure Push Rod Travel

Refer to the Injection timing chart and find the Piston Travel for your timing code. Go in opposite of engine rotation back towards top dead center, watching your camshaft gauge closely, counting each rotation as the gauge comes around back to zero. Pass by top dead center, taking the engine past the piston travel spec and then reverse your rotation back to regular engine rotation stopping right are the piston travel spec. Take note of the measurement on the push rod gauge. How many times did the gauge travel around plus what is the gauge measuring now. The measurement you get is the push rod travel spec. Refer to your Injection timing chart in order to find out if you need to add or take away shims on the cam follower box.

Step 8: Repeat for All Cam Follower Boxes

repeat steps 4 through 7 until you achieve Nominal timing specs on each of the three cam follower boxes

Helpful notes. 

• Thicker gaskets equal lesser degrees of timing travel. 

• For a better performing engine shoot to have the spec within the “nominal” range on the chart. 

• Always torque the cam follower box to the 35 ft lb each time you add gaskets. 

• It is acceptable practice to stack gaskets and shims keeping in mind you always have a permaseal gasket towards the block as the inside gasket. It is ideal to have as few stacked gaskets as possible.

• With a typical push rod dial indicator the indicator is traveling backwards. Keep that in mind when counting and adding the rotations etc. 

• Some engines like the V903 cummins require you to change the cam key way in order to adjust the push tube timing instead of the cam rocker box gasket thickness. 

• A rule of thumb that we have found when trying to decipher how many shims to add is for every .008″ of shims added it will decrease the travel measurement by .002

Pro Tips for Cummins Injector Timing Accuracy

• Thicker gaskets = less push rod travel (retarded timing).
• Every 0.008″ of shim reduces travel by ~0.002″.
• Always torque bolts after each gasket adjustment.
• Use as few stacked gaskets as possible.
• Push rod dial indicators often travel in reverse—track rotations carefully.
• V903 engines require cam key changes instead of gasket swaps.

If you’re troubleshooting injector push rod issues or trying to resolve inconsistent travel readings, check out our guide on injector push rod troubleshooting for practical fixes.

Reference Timing Specs

For detailed push rod travel specs by engine series and timing code, refer to the official Injection Timing Chart Using ST-593 or ST-840. This chart includes nominal, fast, and slow travel ranges for NH, NT, V6-V8, V-12, and other Cummins platforms.

Final Thoughts

Cummins push tube timing isn’t just a rebuild checklist item—it’s a performance-critical calibration. Whether you’re working on a fleet overhaul or a single reman job, following this guide ensures your Cummins engine fires with precision.

Need help interpreting your timing chart or troubleshooting a stubborn follower box? Drop us a message or check out our full Cummins rebuild support library.

Static timing is the process of setting the initial engine timing—while the engine is off—to ensure proper startup and operation. For the Cummins ISX, a modern diesel engine, accurate static timing is essential for fuel injection and valve synchronization. Although the ECM (Engine Control Module) dynamically adjusts timing during operation, static timing establishes the critical baseline.

Why Static Timing Is Necessary for the ISX

• Reliable startup: Static timing gives the engine a baseline timing value that helps it fire up smoothly. Without it, starting can be difficult or impossible—especially after major repairs.
• Avoid engine damage: Incorrect static timing can cause valves and pistons to collide—especially in interference engines. This can lead to catastrophic failure. Setting timing correctly avoids these high-risk scenarios.
• Post-repair setup: Incorrect static timing can cause valves and pistons to collide—especially in interference engines. This can lead to catastrophic failure. Setting timing correctly avoids these high-risk scenarios.
• Baseline performance: The ECM adjusts timing based on speed, load, and other conditions. Static timing sets the “home base” for those calculations. If it’s off, you’ll see reduced power, poor fuel economy, and higher emissions.
• Internal synchronization: The ISX engine relies on precise coordination between the crankshaft and camshafts. Static timing ensures proper injector lift and valve movement at the right crankshaft degrees.

Real-World Technician Insights

Static timing isn’t just a textbook procedure—it’s a common point of confusion among technicians. The following forum excerpts illustrate how often it’s misunderstood or oversimplified in practice:

• On XWeb Forums, one user describes static timing as “just to get you in the ball park,” implying that dynamic timing alone can compensate for poor baseline setup. This reflects a common misconception that leads to performance issues.
• A JustAnswer thread highlights recurring problems with injector lift and valve timing on Gen 2 ISX engines—underscoring the need for precise static timing during assembly and repair.

These real-world discussions reinforce why static timing must be done correctly—not just approximated.

Risks of incorrect static timing

• Knocking or pinging Early ignition creates pressure against a piston still in its compression stroke, leading to knocking.
• Poor fuel economy Late timing causes incomplete combustion. Early timing can also reduce efficiency if pressure peaks too soon.
• Overheating Mistimed combustion generates excess heat, damaging internal components.
• Increased emissions Incomplete combustion leads to excess soot and harmful exhaust gases.

CPL#	Usage	Timing Wedge (Injector Cam)	Timing Wedge (Valve Cam)	Nominal Timing Measurement
(4)0927	ISX CM871	4	6	0.5510
(4)1434	ISX CM871	4	6	0.5530
(4)1437	ISX CM871	4	6	0.5530
(4)2732	ISX CM871	4	6	0.5525
(4)2733	ISX CM871	4	6	0.5515
(4)2734	ISX CM871	4	6	0.5439
(4)2919	ISX CM871	4	6	0.5439
(4)2965	ISX CM871	4	6	0.5439
(4)3167	ISX CM871	4	6	0.5530
(4)3229	ISX CM871	4	6	0.5439
(4)3320	ISX CM871	4	6	0.5439
3745	ISX CM871	4	6	0.5530
3746	ISX CM871	4	6	0.5530
3747	ISX CM871	4	6	0.5510
3748	ISX CM871	4	6	0.5525
3749	ISX CM871	4	6	0.5515
3750	ISX CM871	4	6	0.5439
3751	ISX CM871	4	6	0.5439
3752	ISX CM871	4	6	0.5439
8125	ISX CM870	4	6	0.5468
8127	ISX CM870	4	6	0.5468
8259	ISX CM870	4	6	0.5468
8260	ISX CM870	4	6	0.5468
8281	ISX CM870	4	6	0.5468
8282	ISX CM870	4	6	0.5468
8283	ISX CM870	4	6	0.5468
8284	ISX CM870	4	6	0.5468
8285	ISX CM870	4	6	0.5468
8286	ISX CM870	4	6	0.5468
8287	ISX CM870	6	6	0.5086
8288	ISX CM870	6	6	0.5086
8518	ISX CM870	4	6	0.5468
8519	ISX CM870	4	6	0.5468
8520	ISX CM870	6	6	0.5086
8521	ISX CM870	6	6	0.5086
8522	ISX CM870	4	6	0.5468
8523	ISX CM870	6	6	0.5086
2440	ISX CM570	7	6	0.479
2441	ISX CM570	4	6	0.533
2442	ISX CM570	4	6	0.533
2483	ISX CM570	4	6	0.533
2628	ISX CM570	4	6	0.475
2629	ISX CM570	4	6	0.475
2630	ISX CM570	4	6	0.533
2631	ISX CM570	4	6	0.475
2632	ISX CM570	4	6	0.475
2801	ISX CM570	4	6	0.533
2803	ISX CM570	7	6	0.479
2813	ISX CM570	4	6	0.475
2814	ISX CM570	4	6	0.475
2816	ISX CM570	4	6	0.5330
2834	ISX CM570	4	6	0.5330
2835	ISX CM570	4	6	0.5330
2836	ISX CM570	4	6	0.5330
2837	ISX CM570	4	6	0.5330
2867	ISX CM570	4	6	0.5330
2900	ISX CM570	4	6	0.5330
2933	ISX CM570	4	6	0.4750
2934	ISX CM570	4	6	0.4750
8046	ISX CM570	4	6	0.475
8047	ISX CM570	4	6	0.475
8048	ISX CM570	4	6	0.4750
8049	ISX CM570	4	6	0.475
8082	ISX CM570	4	6	0.475
8083	ISX CM570	4	6	0.475
8084	ISX CM570	4	6	0.475
8142	ISX CM570	4	6	0.4749
8172	ISX CM570	4	6	0.533
8242	ISX CM570	4	6	0.4750
8243	ISX CM570	4	6	0.4750
8244	ISX CM570	4	6	0.4750
8245	ISX CM570	4	6	0.4750
8246	ISX CM570	4	6	0.5330
8247	ISX CM570	4	6	0.5330
8255	ISX CM570	4	6	0.4750
8256	ISX CM570	4	6	0.4750
8257	ISX CM570	4	6	0.4750
8258	ISX CM570	4	6	0.4750
(4)1732	ISX CM570	4	6	0.4544
(4)1771	ISX CM570	4	6	0.4750
2627	QSX CM570	4	6	0.4749
2825	QSX CM570	4	6	0.4749
2958	QSX CM570	4	6	0.533
8081	QSX CM570	4	6	0.4749
8469	QSX CM570	4	6	0.4749
8571	QSX CM570	4	6	0.4749
8587	QSX CM570	4	6	0.4749
8588	QSX CM570	4	6	0.4749
8760	QSX CM570	4	6	0.4544
8761	QSX CM570	4	6	0.4544
8762	QSX CM570	4	6	0.4544
(4)3087	QSX CM570	4	6	0.4544
(4)3088	QSX CM570	4	6	0.4544
(4)8741	QSX CM570	4	6	0.4749
(4)8742	QSX CM570	4	6	0.4749

NOTE: For nominal timing values not available, use wedges to measure timing.

NOTE: For CM871 engines showing symptoms like white smoke or premature oil filter plugging, use ±0.003″ tolerance from nominal. For others, ±0.006″ applies.

NOTE: CPL’s for single camshaft ISX15 CM2250 engines are not contained in this document because injection timing is not set with wedges; however, please note that all ISX valve camshafts are timed with a 6 degree wedge including single camshaft CPL’s not listed.

Here at SRX Engines, we’re more than just a supplier of quality diesel engines and parts – we’re a partner in keeping your vital operations running smoothly. Day in and day out, we hear incredible stories from our customers, tales of resilience, hard work, and the crucial role our remanufactured engines play in their success. Today, we’re excited to share a few of these real-life experiences from the field.

A Long Haul Hero: Reviving a Reliable Freightliner

For owner-operator Mark Olsen, time is money. His Freightliner Cascadia is the backbone of his livelihood, hauling goods across state lines. When his engine finally gave out, the prospect of downtime was daunting. “I was looking at weeks without income,” Mark shared with us. “The quote for a brand-new engine was astronomical. That’s when a fellow driver recommended SRX.”

Mark was impressed by the transparent process and the detailed specifications of SRX’s remanufactured Caterpillar C15. He explained, “They didn’t just slap it back together. Instead, they showed me the rigorous testing, the new components – it felt like getting a new engine without the hefty price tag.”

Mark’s experience highlights a common theme: the reliability and cost-effectiveness of SRX remanufactured engines are a game-changer for those in the transportation industry. As a result, he was back on the road within days, his Freightliner roaring with renewed power. Ultimately, this allowed him to continue serving his clients and providing for his family.

Keeping the Harvest Going: An Agricultural Lifesaver

The demands of farming are relentless, and when crucial equipment breaks down, the consequences can be significant, especially during peak seasons. For Sarah Miller, a third-generation farmer managing a large acreage of corn and soybeans, a sudden engine failure in her John Deere tractor threatened to derail the entire harvest.

“We were in the middle of cutting silage, and the tractor just died,” Sarah recounted. “The local dealership quoted a long lead time for a new engine, and we simply didn’t have that kind of time. Every day lost meant potential crop damage and missed deadlines.”

From Breakdown to Breakthrough: SRX to the Rescue

Desperate for a solution, Sarah’s mechanic contacted SRX. They quickly identified a suitable remanufactured John Deere engine in their inventory and expedited the shipping. “I was amazed at how fast they worked,” Sarah said. “Within 48 hours, we had the new engine on the farm and ready to be installed. It literally saved our harvest.”

Sarah’s story underscores the critical role SRX plays in supporting the agricultural sector. Our ability to provide readily available, dependable remanufactured engines minimizes downtime and ensures that farmers can continue their essential work of feeding our communities.

Beyond the Road and the Field

These are just two examples of the countless ways SRX Engines is making a difference for our customers. For instance, our remanufactured engines are powering construction equipment and keeping marine vessels running smoothly, providing reliable and cost-effective solutions across a diverse range of industries.

We believe that every engine has a story, and we’re proud to be a part of our customers’ success stories. Their feedback and experiences drive us to continue delivering the highest quality remanufactured engines and exceptional service.

Have your own SRX story to share? We’d love to hear it! Connect with us on social media or contact our team directly.

At SRX Engines, we’re committed to providing the power you need, wherever the job takes you – from the long haul on a Freightliner to the demanding work on the farm. Contact us today to learn how our remanufactured engines can keep your operations running strong.