This is a Chevrolet 350 HO ZZ1 crate engine that’s spent 30 years stored in a climate controlled environment, without ever being installed in a car, or even fired up.
It’s now being offered for sale out of Rising Sun, Maryland on eBay with a Buy It Now price of $3,900 USD, potentially making it an quick way to add 345 bhp and 387 lb ft of torque to your car without breaking the bank.
This is a Chevrolet 350 HO ZZ1 crate engine that’s spent 30 years stored in a climate controlled environment, without ever being installed in a car or even fired up.
History Speedrun: The Chevrolet ZZ1 Crate Engine
The ZZ1 debuted in the early 1990s as a reworking of the original ZZZ-stamped 350 H.O., addressing the first engine’s cold-start piston rattle along with a number of smaller internal updates, and then continuing in essentially unchanged form for the next few years. By the time the ZZ1 gave way to the ZZ2, ZZ3, and the long-running ZZ4, the basic architecture had become an established crate engine template that helped to define Chevrolet’s small block crate engines right through to the current day.
By the late 1980s, factory replacement engines had already been available over the parts counter for decades, but they were essentially production motors in a wooden box. The hot-rodding alternative was to scavenge a junkyard small block and rebuild it, or to assemble a custom engine using aftermarket speed shop parts.
GM Performance Parts saw an opening in the market, and in 1989 the division introduced the 350 H.O., this was a purpose-built, fully assembled high-performance small block V8 sold with a factory warranty – a first for the segment. Its block-pad stamping was ZZZ, and it would be that that letter code that would give the engine (and its successors) their name.
The ZZZ used a cast-iron four-bolt main block, a forged-steel crankshaft with a one-piece rear main seal, forged connecting rods, and hypereutectic pistons running 9.8:1 compression. The heads were aluminum castings closely related to the L98 Corvette’s 113 casting, with D-shaped exhaust ports, 58cc chambers, and 1.94-inch intake and 1.50-inch exhaust valves.
A single-pattern 235º hydraulic-roller camshaft with 0.480-inch lift and a 114º lobe-separation angle sat on top, fed by a Z28-style high-rise dual-plane aluminum intake manifold set up for a Holley four-barrel carburetor. Output was rated at 345 bhp at 5,600 rpm and 370 lb ft of torque at 3,600 rpm.
The L98 was the most sophisticated production Gen I small block of its time, but it was tuned for emissions compliance and topped out 245 bhp in the Corvette. The 350 H.O. took the same head architecture, paired it with an aggressive camshaft and a carbureted top end, and sold it as a factory-assembled crate engine and long-block package for hot-rod, off-road, and pre-1979 street use.
It’s now being offered for sale out of Rising Sun, Maryland on eBay with a Buy It Now price of $3,900 USD, potentially making it an quick way to add 345 bhp and 387 lb ft of torque to your car without breaking the bank.
GM later stated that 500 ZZZ engines were sold in the first year, though a definitive total production figure before the ZZ1 hasn’t been published (as far as we could tell, anyway).
The ZZZ had one obvious problem from the very beginning, it rattled. The pistons used zero-offset wrist pins, which combined with the hypereutectic alloy and the engine’s tight cold clearances resulted in a pronounced cold start piston slap. The noise faded once the engine warmed, but it was loud enough to alarm owners who had just spent the equivalent of a used car price on a brand-new factory motor.
The ZZ1 Engine Arrives
The ZZ1 was GM Performance Parts’ answer – the piston design was revised with offset wrist pins, which shifted the piston’s rocking motion at top dead center and more or less silenced the cold-start clatter. At the same time, the single-roller timing chain was replaced with a butt-link chain, and the cam-retainer and intake-manifold accessory bosses were revised.
It kept the same four-bolt block, forged crank and rods, 235º roller cam, L98-derived aluminum heads, dual-plane intake, and 345 bhp output rating.
The ZZ2 followed shortly after, sharing the ZZ1’s part number and continuing the same basic specification with some minor production updates. Some publications treat the two as separate engines and others treat them as a single revision – the GM parts catalog lists them under the same number, suggesting they were closer to running production changes than distinct models.
The ZZ1 and ZZ2 generation was relatively short-lived – in 1992 GM Performance Parts introduced the ZZ3, which swapped the aggressive 235º single-pattern cam for a milder split-pattern grind at 208/221º duration with 0.474/0.510 inches lift.
The seller recently removed the crate cover and original protective plastic to verify the engine’s condition, hand-rotated the assembly to confirm it turns freely, and then re-covered and re-protected it for storage.
The change helped to widen the torque curve and improved idle quality, all without sacrificing the peak horsepower rating. A lower-rise dual-pattern intake replaced the earlier high-rise unit, clearing Corvette hoods and accepting either a Holley square-flange or a Rochester Quadrajet spread-bore carburetor. The ZZ3 carried the same 345 bhp rating as its predecessors.
The ZZ4 arrived in 1996 with flat-top pistons, higher compression, and a 355 bhp rating, and went on to become the longest-running variant in the series, remaining in production until 2014. The ZZ5 followed at 400 bhp, and the 405 bhp ZZ6 arrived for 2016 as the ZZ5’s replacement and remains the current carbureted ZZ-series engine.
The ZZ1 proved the concept of a warrantied factory crate engine, and it proved that concept was viable for ongoing production. It helped to set the template that Ford and Mopar would follow into the 1990s and that GM itself would continue refining through the LS-based crate program that defines the modern era of factory-built crate engines.
The Chevrolet ZZ1 Crate Engine Shown Here
This is a “New Old Stock” ZZ1 350 H.O. crate engine, stamped 10185025 and date-coded 9021 F1, that is said too have spent more than 30 years in climate-controlled storage. It was bought new and set aside in 1991, it’s never been installed in a vehicle, it’s never had coolant run through it, and it’s never been fired up. Output is the standard ZZ1 rating of 345 bhp and 387 lb ft of torque.
The engine is built to factory ZZ1 specification, with a four-bolt main block, a one-piece-seal forged steel crankshaft, a hydraulic roller valvetrain, 1.5 ratio rockers under factory center-bolt valve covers, the high-rise dual-plane aluminum intake, and aluminum L98 heads with 58cc chambers.
The seller recently removed the crate cover and original protective plastic to verify the engine’s condition, hand-rotated the assembly to confirm it turns freely, and then re-covered and re-protected it for storage.
This is a “New Old Stock” ZZ1 350 H.O. crate engine, stamped 10185025 and date-coded 9021 F1, that is said too have spent more than 30 years in climate-controlled storage. It was bought new and set aside in 1991, it’s never been installed in a vehicle, it’s never had coolant run through it, and it’s never been fired up. Output is the standard ZZ1 rating of 345 bhp and 387 lb ft of torque.
They note that after this long sitting, new valve springs would be a sensible precaution before firing it up. It’s offered as a collector-grade piece suited to a high-end 1990s-correct build, a third-generation Camaro or Firebird upgrade, or a period-correct street rod – according to the seller.
It’s being offered for sale on eBay out of Rising Sun, Maryland with a Buy It Now price of $3,900 USD, and you can visit the listing here if you’d like to read more about it or register to bid.
Images courtesy of Esso 40
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Silodrome was founded by Ben back in 2010, in the years since the site has grown to become a world leader in the alternative and vintage motoring sector, with well over a million monthly readers from around the world and many hundreds of thousands of followers on social media.
