Engine Forensics — Inside A SBF After Completing The Baja 1000

Engine Forensics — Inside A SBF After Completing The Baja 1000

After 45 hours of continuous torture, we were still in the running to finish the prestigious SCORE Baja 1000. Other than during pit stops, our 410-cubic-inch small-block Ford Windsor had not shut off. We were 55 miles from the finish line of the 1,135-mile race. With three hours left before timing out, it was just a matter of not doing something dumb.

At about 9:00 am, just outside of the small village of Comondu in southern Baja, running slightly uphill at a strong pace, we heard a single backfire… then silence. The race car drifted to a stop on the side of the course. Repeated cranking, but no fire. Fuel pressure? Check! Air? Check! Spark? Negative! We got to work replacing the coil with no luck.

We swapped in our second MSD ignition box, still no luck. Checking the cap and rotor, no issue. That is, until we tried turning the engine over with the cap removed. Our test confirmed something failed between the camshaft and the rotor. Out came the distributor assembly; lo and behold we found our problem — a worn-out distributor gear. It also happened to be one of the few spare parts we didn’t have on board.

This is the original bronze gear consumed by the engine.

Some satellite-phone calls were made, and our support team located a spare distributor (and gear) and were en route. By the time they arrived we’d stripped the engine of accessories so it was only a matter of finding TDC in the number-one hole and installing the new parts. However, the decision loomed whether to push on to the finish line and risk further damaging a $30,000 race engine, or limp her to the nearest road and find the trailer.

We hadn’t come this far to save money — it was all-or-nothing in our minds. Before leaving the scene we were told “go easy for about three miles. If there are no issues, go for it.” That plan lasted about 30 seconds before all hell broke loose and we were streaking towards the finish line. Long story short, we finished with nine minutes to spare. This is the point at which the story of our engine begins.

The rear of the intake gasket just barely avoided being pushed out.

Well Doc, How Bad Is It?

With over 1,135 miles of high-RPM wear and tear, it was time to find out just how much punishment we inflicted on this endurance engine. It was evident that the engine already had plenty of bronze (from the distributor gear) find its way through oil passages until the oil filter could capture it. But what about other contaminants such as sand and fuel-borne contributors?

To handle the forensics, the engine was delivered to SouthWest Racing Engines (SWRE) in Covina, California. Having built this engine and many others involved in desert racing, its team was ready to dig in. To kick things off, the engine received a light external air bath to reduce the chance of introducing external contaminants while the tear-down took place.

Evidence of contaminants in the cylinder head’s oil drain-back hole.

Next, a 3-ounce oil sample was taken from the engine and shipped off to SPEEDiagnostix for analysis, along with a 3-ounce sample of fresh oil reserved from the original case of oil used in this engine. The idea is to match physical findings with chemical analysis for confirmation as well as to examine chemical properties which may not be so visually obvious.

While not absolutely required, sending new and used oil samples will provide a more comprehensive view of what has been introduced to the oil throughout the useful life. SPEEDiagnostix maintains a well-stocked analysis library of commonly available lubricants. While taking oil samples, the magnetic oil drain plug was inspected for debris. To the delight of the team, minimal ferrous debris found its way onto the drain plug.

The magnetic drain plug could have been a whole lot worse.

Inspecting the Top Half

Starting from the top-down, the carb was externally inspected. Significant sand and dirt was found to have passed by the filter assembly and worked its way down into the intake manifold. Not a good start, but considering the engine daw mid-race air filter changes, it’s possible this is a result of those activities.

Saving it for later, the carb was removed and set aside. Investigation of the backup distributor drive-gear showed significant wear. Had this been the original distributor gear, fingers could be pointed, but this was simply the backup (and a used backup at that), likely making this wear more of a symptom than the root cause.

Quite a bit of dirt made it past the filter, through the carburetor and into the engine.

Next the spark plugs were checked for obvious problem signs. While the electrode and core were a little dark in color (more black than brown), Steve of SWRE confirmed that the coloration wasn’t a warning sign. “It’s not burning oil, but the air/fuel ratio is rich,” he says. “It also looks like this thing idled for a while after the finish line.”

This is the replacement distributor gear after only 55 miles of use.

Further investigation found no excessive deposits and a gap-check showed all plugs were well within spec, some having not moved since being set and installed before the race.

Attention now turned to the heads and upper valvetrain. A quick look at the installed Woodward Heat Tabs indicated the heads did not see excessive temperatures. Removing the valve covers allowed direct observation of what contaminants found their way into the oiling system and/or contributed to system wear.

While not full of dirt/sand, there was evidence of contamination where dirt had fallen out of suspension in oil drainage passageways leading back to the crankcase. Before removing the heads, valve lash was measured on all intake and exhaust valves. Intake valves indicated 0.011 to 0.016 inch, exhaust valves indicated 0.016 to 0.020 inch. Both of those measurements fall within spec and indicate there probably wasn’t much valve cupping or valve seat damage. This hypothesis was later visually confirmed.

The heat tabs indicate the cylinder heads never got to dangerous levels during the race.

Relieving the spring pressure on the rockers allowed removal of the pushrods, which looked clean and all measured within 0.001 inch. Next, the lifters were pulled from their galleys and inspected. Unfortunately, an indication of contamination and wear showed up. Dimensionally, the lifters checked out fine, so the wear was documented and the lifters were scheduled to be polished to see if there was more life left in them or if replacements would be required.

Digging Into the Short-Block

After removing the heads, all pistons received a thorough examination before being removed from their cylinders. Obvious from the start was a reasonable amount of carbon buildup on the face of each piston. This didn’t raise suspicions at SWRE as the vehicle owner indicated the race car spent significant time at idle loading on and off the trailer multiple times.

While examining piston tops, it was obvious the sand seen in the air filter housing worked its way into the cylinders. The bottom face of each cylinder showed scratches running longitudinally along the cylinder wall. Scraping a fingernail across the scratches indicated more than surface marring, so the issue was documented and would be examined later during the machining processes.

While there were wear marks on the lifters, the diameters measured within .001 inch of ideal, so they were cleaned up and reused.

Once removed, the piston rings were examined and found to have similar longitudinal scratches running down their circumference. This was definitely an indication sand was trapped between the cylinder wall and piston rings on its way to the oil galley.

Before removing the crankshaft and camshaft, the timing chain was visually inspected for wear and stretch. “As expected, the chain hasn’t stretched too much, but by no means is it new,” says Steve.  The chain was treated as a consumable, and a replacement was added to the growing list of parts needed.

This wear pattern was on both the cylinder wall and piston skirt.

With the pistons removed, the main and rod bearings were inspected for wear. Despite the sand traveling through the cylinders, the bearing material didn’t show much wear. Instead, the bearings had a slight sparkle to them, where bronze from the distributor gear was trapped.

Steve took a few minutes with a Sherlock Holmes-style magnifying glass to look over all the bearing surfaces. “The bearings did what they were supposed to do: capture the bronze that would otherwise find its way into other parts of the rotating assembly,” he concluded.

There was a significant amount of bronze material embedded in the main bearings.

Being the epicenter of the wear and tear Baja inflicted on this engine, the camshaft received a lot of attention once removed. Most notable was the wear on the drive face of the camshaft’s drive gear teeth. While not as severe as the wear seen on both distributor drive gears, the wear on the cam gear indicated significant loading and abrasion.

Reviewing documentation for this engine assembly and break-in, notes indicated the engine had been broken-in on high-zinc mineral oil. After break-in, the engine operated on full synthetic 20W-50 oil. Procedurally, all the i’s were dotted and t’s crossed, so the looming question was, “where is this wear coming from?”

It wasn’t just the distributor gears that wore, as the camshaft’s drive gear also exhibited significant wear, suggesting foreign contaminants.

Finally making his way to the bottom of the engine, Steve removed the Melling oil pump and tore it down to see what found its way inside. Similar to the timing chain, the oil pump was a consumable when swirl marks were discovered on the pump and impeller faces.

While running a fingernail across the swirl marks, it didn’t appear that significant damage occurred, compared to what was found previously. However, Steve made no bones about it, saying: “The oil pump is the heart of any engine, and nothing will last if there’s any hiccup with the pump. Don’t be cheap, don’t take chances. Buy a good pump, and buy a new one whenever there is a question.”

To make this a thorough examination, the oil filter housing was cut open to look at what was captured inside. Using the SWRE lathe, the outer filter body was cut from the filter material to reveal a sandy and sparkly mess, as was expected. While not overly saturated with sand, there was clearly an entire bronze distributor gear ground up in the filter pleats.

Getting the Lab Results

The act of rebuilding any engine is an opportunity to learn and improve, rather than it just a matter of learning how all the parts go back together. This rebuild was a chance to think critically about each component, how it works in the system and how the symptoms can be interpreted for improvement.

About the same time the engine was torn down and analyzed in detail, Lake Speed, Jr. of SPEEDiagnostix had already received, analyzed, and summarized his findings for both oil samples. The message back from Speed started with: “I’ve never seen manganese numbers this high!”

These two SPEEDiagnostix reports show the baseline oil sample on the left, and the one out of the engine after the race, on the right.

Not exactly what anybody wants to read about their oil analysis. Online searches for “sources for engine manganese” might as well have been a WebMD search for “why does my stomach hurt?” There were just too many stories and too many rabbit holes. Speed continued to expand on his findings. “I suspect the fuel may have contained a ton of MMT,” he opined. “I don’t think the engine would still be running if the valve guides had worn that much.”

After revealing to Speed that the engine had eaten a bronze distributor gear while racing through Baja, his analysis became more directed. “The copper levels are certainly tied to the excessive wear on the distributor gear(s), and that ties to the iron wear levels as well. The main takeaway is the amount of wear caused by the sand/dirt, which shows up as silicon.”

That part of the conversation highlighted how important it is to have a candid discussion with your engine builder, parts suppliers, and oil analyzers. Rely on and learn from their experience — they have years of it and love helping solve issues.

Based on the hardware inspection and oil analysis; the working theory is this 410 Windsor was the victim of two possible culprits: sand intrusion and manganese-enhanced wear. The first confirmed culprit — sand — made up the entirety of the 1,135-mile race-course. Throughout the engine cleanup and tear-down process, abundant amounts of sand were found, to the chagrin of the engine owner. Despite extreme care in assembly and frequent air filter changes, Baja made its way into the engine.

The Wix oil filter was cut open to inspect the filtration media.

The second potential culprit is still a hypothesis, but the evidence is compelling for excessive manganese wear.  There are multiple possible sources in which the element can be found in varying concentrations depending on the bronze alloy used. In this case, the  MSD distributor gear was made of Ampco 45 Aluminum-Bronze alloy, which contains significant amounts of manganese.

While it’s possible that is what SPEEDiagnostix detected during the analysis, the ground-up particles of bronze tend to get trapped by a filter or impregnated in bearing materials. The oil-analysis process looks for much smaller particle sizes than are typically visible.

An additional working hypothesis for the source of manganese is its introduction via local (Mexican) fuel and additives. The fuel used during the Baja 1000 was a mix of 93-octane pump-gas and race-fuel additives. Looking deeper into MMT sources and concentrations, BOOSTane — the manufacturer of the fuel additives used — was contacted.

“We know in countries like Mexico, additives such as manganese are used to raise the octane of pump fuel due to the lack of quality in the refining process,” says Ian Lehn, President of BOOSTane. “We’re familiar with seeing elevated MMT levels, as this is one (of many) ingredients we use in BOOSTane’s total solution.”

New piston rings were in order after the race. The dirt that made its way into the engine took a toll.

In order to receive maximum benefit from additive packages such as those available in BOOSTane, Lehn stresses that delivery of the active ingredients is imperative to efficacy, as well as long term build-up. If the solution doesn’t account for this, the resultant manganese build-up can be detrimental.

In his Technical Bulletin “Where Does All That Metal Come From?” author John S. Evans writes: “Some lead-replacement fuels contain manganese as an anti-knock additive. It can show up as a combustion by-product in the oils of petrol engines using these types of fuel. In very rare cases, manganese exists as an additive,” which confirms the working hypothesis.

Assuming fuel consumption of 3 miles-per-gallon over 1,135 miles, this race engine saw just under 400 gallons of fuel processed in less than 48-continuous hours. Is it possible that enough piston ring blow-by occurred (remember the longitudinal cylinder wall scoring) that the manganese levels were elevated to a point allowing it to be an abrasive contaminant in and of itself, and not just a symptom of material wear or an additive package?

Not Repeating the Past

Postulations aside, this engine functions in the real world, and real solutions were needed to move forward. First, to combat sand intrusion, Injen Technology was contacted regarding the program’s air filtration needs and potential sand-intrusion countermeasures.

“Proper filter sizing for this type of environment is key,” says Injen Director of Global Business Development, Jay Crouch. “Knowing engine volume, maximum RPM levels, and operating duration are critical to successful filter deployment.” Understanding the race environment can also help Injen to properly spec a filter that may see sand, silt, water, or other such conditions.

The original timing chain took a beating and loosened up, but didn’t fail.

“Wherever filter seals meet housings or filter caps, a trade secret is to smear copious amounts of Vaseline or mild bearing grease on the filter edges,” Crouch reveals. “This will help to capture sand and dirt that may otherwise find its way around filter elements.”

To minimize the potential for high MMT/Manganese concentrations in fuel and oil dilution in the future, care will be taken to utilize only enough octane rating to satisfy the anti-knock requirements of the engine. Remember, octane doesn’t increase power; it simply fights knock. For this 410 Windsor, that’s simple to do because of its low compression ratio and can include minimal volumes of fuel quality enhancers such as BOOSTane.

Rebuilding the Mill

To address the cylinder scoring, the block was delivered to Manny Moreno Enterprises in Torrance, California. Moreno performed a light hone that left the cylinder walls with appropriate crosshatching to properly seat the new piston ring assemblies. While he had the block, Moreno also took the time to align-hone the cam journals in preparation for new cam bearings.

Next, SWRE contacted Trent Goodwin and Aaron Mick at COMP Performance Group to discuss some of their findings and ask for recommendations on replacement parts. Both agreed the wear seen on the distributor drive gear was an artifact of outside contaminants. And both said that by addressing those external conditions first, significant upgrades or material changes aren’t warranted. New components — comparable to the previously used pieces — would be adequate to get the engine back into fighting shape.

With the amount of contamination in the engine, a new camshaft thrust bearing and plate from COMP Cams was an inexpensive piece of insurance.

The replacement parts list from COMP Cams was surprisingly short; a new camshaft, cam thrust bearing, and a timing set (P/N: 3135) to replace what had become a little slack over the last 1,135 miles. The camshaft (P/N: 35-772-8) is a direct replacement for the one damaged during the race. It’s from COMP’s Xtreme Energy lineup and is a street-oriented mechanical-roller profile. The operating range of 3,000 to 7,000 rpm is perfectly suited to the operating range of the 410 Windsor throughout the desert race.

It’s not an overly aggressive camshaft, with .614 inch of lift on the intake and .621 inch on the exhaust. Duration-at-.050 numbers of 248 degrees on the intake and 254 degrees on the exhaust with a 110-degree LSA. The cam profile performed exceedingly well throughout the race, and the team saw no reason to change the cams specs while the camshaft was out of the engine.

The new camshaft thrust plate and thrust bearings (P/N: 3120TB) were a precautionary measure. Since there was so much dust and dirt intrusion throughout the engine, there was no reason not to replace the bearings. It’s a relatively inexpensive part to replace and ensure that it’s not a failure point down the road.

The COMP Cams Xtreme Energy camshaft for this engine is designed to make power in the 3,000 to 7,000-rpm range. After the wear on the distributor drive gear, the whole camshaft was replaced with an identical new camshaft.

The COMP Hi-Tech Roller Race Timing Set (P/N: 3135) features a cast-iron camshaft gear and an induction-hardened billet-steel crankshaft sprocket. It can be installed straight-up, four-degrees advanced, or four-degrees retarded. The chain included is a heavy-duty double-roller design, which uses large link-pins and has been heat-treated and pre-stretched, that should prevent the issue encountered with the factory timing set from reoccurring.

Next, SWRE went to work cleaning up the rotating assembly used in the rebuild. Elbow grease was the name of the game on most parts. Due to strict environmental laws, caustic solvents are a thing of the past. Those solvents were a huge time-saver when it came to clean up. Lately, Steve uses a heated sonic tank filled with kerosene to start the cleaning process on parts.

The COMP Cams’s Hi-Tech double roller timing set adds additional strength to the chain itself, not to mention hardened gears to provide additional insurance on the engine.

A brief 15-to-20-minute soak and most parts come out ready for install. Those with stubborn debris may take extra attention but are usually ready to go after having marinated for a short while. While not all materials can be exposed to kerosene, and it must be removed entirely from parts after cleaning to avoid contaminating new engine oils, it does work well.

For the remainder of the Windsor rebuild, attention to detail was used in abundance. SWRE treated this build with the same care it received during its very first assembly, checking and hand-filing piston ring gaps, confirming oil-passage alignment and installing new cam bearings.

Checking rod bolt stretch during installation is standard procedure, but SWRE’s most notable assembly procedure is not — it safety wires the rod bolts. While thought of as overkill by many, the off-road racing environment constantly looks for hardware to loosen and parts to kill. For non-rotating parts, safety wiring can save a lot of headaches (and dollars) when applied correctly.

To finish off the rebuild, the Holley Performance 750cfm carb was completely disassembled and treated to a soak in the sonic cleaning machine. The squirters, spring-loaded needles, and overflow screens were all carefully brushed and examined. A fresh rebuild kit and phenolic spacer provided all the gaskets necessary to reassemble and install this Holley.

SWRE is a huge fan of safety wire, using it anywhere fasteners can’t be easily accessed and checked for torque.

What’s the takeaway?

This endurance engine saw long stretches of action in an extremely dirty environment. Dirt intrusion was the predominant contaminant along with possible chemical contamination. That contamination led to advanced wear on the distributor drive gear, ultimately leading to its failure. Preventing these issues in the future will require care be taken during filter and gasket installation, along with possible replacement throughout racing events.

To address the chemical contamination, the fuel-to-additive ratios will need to be examined and adjusted. In the event there is no adjustment possible, the use of race fuel only might be required. From an octane perspective, this is unnecessary, but with the quality of local pump-gas in question, sealed race fuel may be the only method of fighting contamination.

Realistically, racing over 1,000 miles in the Baja desert is one of the harshest environments one can expose an engine to. With that in mind, attention to detail will help an engine make its way toward the finish line, but a tear-down and refresh is probably just the cost of doing business in Mexico, regardless of the amount of preparation.

Torn down, analyzed, and rebuilt better than before, the 410-cubic-inch Windsor engine is now ready for next year’s running of the brutal desert endurance race.

Article Sources

About the author

Joe Palmer

Joe Palmer serves as an Engineer at a major OEM and has over 15 years of experience with OEM vehicle testing, emissions, OBD certification, and advanced “Eco” powertrain systems. Palmer’s current focus is on advanced fuel economy calibration methods in Eco powertrain systems. He holds a Bachelors in Mechanical Engineering and attributes winning the Baja 1000 as one of his highest automotive based achievements.
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