General Motors recently paused production of the Chevrolet Performance 602 crate engine (aka CT350). They done so after numerous reports of insufficient oil clearance and undrilled oil drain holes in the castings of the engine.
“Yes, production has been paused and we are looking into issues raised in the field,” said Bill Martens, of Chevrolet Performance. “There are a variety of issues rooted in insufficient oil clearance that has manifested in several areas.”
Engine builders who blueprint and prep the engines for racing first noticed problems in April when GM switched from cast-iron crankshafts to forged ones.
“The forged cranks are not exactly the same as the cast-iron cranks,” said Bob Godgart, of KillerCrate. “A wider crankshaft — just by thousandths of an inch — results in not enough clearance between the crank bearing and the crankshaft, which results in the bearing being starved of oil. We’re talking a measurement of just .002″ clearance from journal to bearing.”
Reports from the field tell of consumers using break-in oil, which is thinner, without issue on the new 602s. However, when the recommended 20W-50 oil is used, it is too thick to lubricate between the crank and bearing. Use of the thicker oil has resulted in spun bearings, seized engines, and thrown connecting rods. For the time being, Godgart recommends using thinner oil with the recently produced 602 engines.
“We found that 5W-30 or Maxima 30 can possibly lubricate the bearings properly,” Godgart said. “If the engine does not fail on the first race, and goes five to six races running okay, we recommend keeping the oil thin and preheating the engine before firing it up.”
Godgart discovered a new problem with the Chevrolet Performance 602 crate engines he recently received in his shop.
“The 602 crate engines built in August have no oil return hole by the distributor at the back of the engine,” said Godgart. “The hole is cast, but it has not been drilled out. These engines will blow up as soon as they are used. Only a dyno could possibly catch the problem before it is too late.”
Cory Hedgecock, of Eagle Racing Engines, listed several issues he has found with the new Chevrolet Performance 602 crate engines.
- The rod side clearance is too tight.
- Inconsistent main end rod bearing clearance.
- The drain back holes in the lifter valley have not been drilled.
- Nine of 10 engines received have rod bearings that have been chewed up, with crankshafts that have been scratched by trash left in the engine during the manufacturing process.
Hedgecock expressed his frustration.
“We don’t get paid extra to fix rod side clearance — we’re blueprinting engines,” Hedgecock said. “These are problems that should not exist in GM engine production. There is no excuse. GM raised the price of the 602 crate from $3,500 to $5,000 and this is what we get? The price went one way and workmanship the other way.”
Martens said engineers are contacting customers in each case reported. Godgart confirmed that GM engineers have had several conversations with his shop.
“This problem is what engineers call a ‘clearance stack up,’” said Martens. “We’re looking at everything — for example, bore sizes, crank pin sizes, bearing sizes, tolerances, and more. We’re looking at variances in oil pressure. We don’t assume anything. We’ve been building this engine since 1955. We know that the thin film of oil necessary to lubricate the engine has to be consistent. We will find the cause.”
Martens pointed out that the problems with the Chevrolet Performance 602 crate engine are not across the board.
“There are a lot of variables, but the problems do not appear in every engine,” Martens said. “Our plan is to pause, investigate, and correct the problems. We’re talking measurements four decimal points out, and there is not room for error, and we have to check a lot of parts.”
GM moved production of the Chevrolet Performance 602 crate engine to solely within the United States two years ago. They manufacture the engines in three locations on low-volume production lines.
“Problems increased tenfold when production was taken out of Mexico and moved to the United States,” said Hedgecock. “The workmanship was better in Mexico. The question is why?”
Martens said a multitude of issues resulted from one main problem affecting the entire world.
“We’re digging out of a perfect storm,” Martens said. “There are shortages in the supply chain. There is a shortage of manpower. All of this is because of Covid-19.”
Both Eagle Racing Engines and KillerCrate struggle to salvage the Chevrolet Performance 602 crate engines they have.
“A [602 crate engine] block with no heads needs 18- to 19 ft-lb of torque to turn over manually,” said Hedgecock. “We’ve had them come in here needing 42 ft-lb to turn over. These engines will not make it out of the shop.”
With the Chevrolet Performance 602 crate engine still in high demand, shortages of 602 crate engines will continue for the near future. However, Martens said that they will start getting back on track soon.
“We are planning to go back into production next week,” Martens said. “With the backlog, it will be well into the new year before we can get ourselves dug out of this. This is not like the chip shortage, where the product can be completed and the chip popped in when it arrives. These problems go back to the core. We’re building from the ground up again.”
Sources
Chevrolet Performance
Detroit, Michigan
chevrolet.com/performance-parts
Eagle Racing Engines
Knoxville, Tennessee
865-408-1000
eagleracingengines.com
KillerCrate
Albany, New York
518-469-2932
killercrate.com
The Outside Groove Director of Photography has written hundreds of stories since the website’s inception. This year marks his 54th year of covering auto racing. Adaskaveg got his start working for track photographer Lloyd Burnham at Connecticut’s Stafford Motor Speedway in 1970. Since then, he’s been a columnist, writer, and photographer, in racing and in mainstream media, for several outlets, including the Journal Inquirer, Boston Herald, Stock Car Racing, and Speedway Illustrated. Among Adaskaveg’s many awards are the 1992 Eastern Motorsport Press Association (EMPA) Ace Lane Photographer of the Year and the 2019 National Motorsports Press Association (NMPA) George Cunningham Writer of the Year.
