Decode a Intek (single-cylinder OHV) Stamp
In production: 1997-present.
The Intek single-cylinder line is Briggs & Stratton's overhead-valve tractor engine family: one cylinder, a vertical crankshaft, and a cast-iron cylinder sleeve, built in four displacement blocks - 344 cc (210000 series), 465 cc (280000 series), 501 cc (310000 series), and 540 cc (330000 series). Ratings run from roughly 11.5 to 21 gross horsepower depending on block and tune.
These engines powered the mainstream lawn-tractor fleet for a generation - Craftsman, MTD, Husqvarna, Poulan Pro, Troy-Bilt, and John Deere consumer riders - and they stay in service for decades, which is why their service data (valve clearance, head torque, oil capacity, plug and filter numbers) is looked up constantly. The same basic block was also sold in PowerBuilt and Professional Series trim; the stamped model number, not the decal, tells you which engine you actually have.
One caution the stamp protects you from: the earliest 28-series tractors also carried flathead (L-head) engines under similar marketing. If your stamp is a flathead model, Intek OHV valve and torque data does not apply - check the model against this family's records before ordering parts or setting clearances.
Where the stamp is
On Intek single-cylinder OHV engines the Model-Type-Code is stamped into the metal valve (rocker) cover on most production, and on later engines it also appears on a printed label on the blower housing. Check the valve cover first; if the cover has been replaced, check the blower-housing label and the edge of the blower housing above the spark plug. (Per Briggs & Stratton engine-identification literature and dealer ID guides.). It is stamped into the metal, not printed on a sticker - wipe the area clean and read it at an angle if it is faint.
Worked example
A real stamp from this family: 31C707 3346 110510ZD
| Part | Value | Means |
|---|---|---|
| Model digits 1-2 | 31 | Displacement class: 31 cubic inches nominal (the 310000 block; published displacement 501 cc). |
| Model digit 3 | C | Basic design series letter for this block generation. |
| Model digit 4 | 7 | Vertical crankshaft (PTO) orientation - the rider/tractor configuration. |
| Model digit 5 | 0 | Plain (sleeve) PTO bearing, no reduction or auxiliary drive. |
| Model digit 6 | 7 | Electric starter fitted. |
| Type | 3346 | Trim and equipment configuration code for this build (carburetion, controls, alternator, and application options). Type 3346 is documented on this model in dealer engine listings. |
| Code digits 1-2 | 11 | Build year: 2011. |
| Code digits 3-4 | 05 | Build month: May. |
| Code digits 5-6 | 10 | Build day: the 10th - so this engine was assembled May 10, 2011. The code is a build date, not the tractor's model year or sale date. |
| Code suffix | ZD | Assembly plant / production line suffix. |
Reading the type
The Type is a four-digit trim code (often followed by a revision suffix such as -G1 or -E1) that pins down the exact build: carburetor and control setup, alternator output, muffler and fuel-pump fitment, and the equipment application. Unlike the Model digits, the Type digits do not decode position-by-position from any public rule - the authoritative Type-to-trim mapping lives in Briggs & Stratton Illustrated Parts Lists, which key parts to Type ranges. Practical rule: Model alone is enough for family specs (displacement, clearances, oil); Model + Type is required for parts. If a Type is not in a verified table, we decode Model + Code and report the Type trim as unlisted.
The model-number rules
Reading the model number
- Digits 1-2Displacement (cu in)
- Next digit/letterBasic design series
- Next digit/letterCrankshaft orientation: 0-4 or A-G horizontal, 5-9 or H-Z vertical
From the Briggs & Stratton model number key.
PTO bearing / drive digit
| 0 | Plain bearing |
| 3 | Ball bearing |
| 4 | Ball bearing, pressure lubrication |
| 5 | Plain bearing, gear reduction (6 to 1), CCW rotation |
| 6 | Ball bearing, gear reduction (2 to 1), CCW rotation |
| 7 | Plain bearing, pressure lubrication |
| 9 | Plain bearing, auxiliary drive |
Starter digit (last)
| 0 | Without starter |
| 2 | Rewind (recoil) starter |
| 5 | Electric starter |
| 6 | Alternator only |
| 7 | Electric starter with alternator |
The code: build date
The code's first six digits are the build date, read YYMMDD - two-digit year, month, day. The trailing characters are the assembly plant and line. A code gives a build date, not a sale date or the year of the equipment it powers.
Intek (single-cylinder OHV) engines in the database
- Intek 31R777 - The later R-series tune of the 501 cc block - rated 15.5 HP in Briggs manual-derived service data.
- Intek 33R877 - The current 19 HP Intek single - the standard repower for 42-46 in. riders.
Quick answers
Where is the model number on an Intek single-cylinder engine?
Start with the metal valve cover - on most Intek OHV singles the full Model-Type-Code is stamped into it. Later engines also carry a printed label on the blower housing. You need all three numbers for parts.
What does the Code number tell me?
The first six digits are the build date as YYMMDD, followed by a plant/line suffix. It tells you when the engine was assembled - not when the tractor was sold or its model year, which can differ by a season or more.
My tractor says 17.5 HP but the stamp says 31C707 - which do I trust?
The stamp. Decals are marketing for the tractor model line; the stamped Model-Type-Code identifies the exact engine build, its displacement block (501 cc for 31C707), and the parts that fit it.
Can I decode the Type digits letter by letter like the Model?
No. The Type is a lookup code, not a positional code - its meaning comes from Briggs & Stratton parts-list tables for that model. A Type cannot be decoded digit-by-digit from a generic chart.