Onan Engine Torque Specs

Cylinder head bolt torque at a glance

HighMediumLow= how many independent sources agree

Onan's Performer series is a side-valve, air-cooled, horizontally-opposed twin built by Cummins-Onan, commonly fitted to garden tractors of the era. The family covers four models across three displacements — P218 and P220 share the same 3.250 x 2.875 in bore and stroke, 47.7 cu… Read the rest ›

in (782 cc), differing only in rated output (18 vs 20 HP) — and Onan's own manuals group them into two torque scopes rather than four: the P216/P218/P220 share one Assembly Torques column with cylinder head BOLTS, while the larger P224 has its own column with cylinder head NUTS and several other figures that genuinely differ from the smaller three. Every torque value below is read directly off Onan's own Performer Series Engine Service Manual (965-0762) and Operator's Manual (965-0167), including the two-part cylinder head torque that depends on which head gasket (asbestos vs. graphoil, P216-220) or washer configuration (with/without compression washers, P224) is fitted — pick the row that matches your engine rather than the first number you see.

Where these numbers come from. 38 published figures, 6 confirmed gaps, every source named. How we checked ›

Two Cummins-Onan publications were used: the Performer Series Engine Service Manual (965-0762, 12/1996) for every torque value and procedure, and the Performer Series Engine Operator's Manual (965-0167, archive.org edition dated 2-96) for the spark plug torque, which the service manual never states. Every figure below was checked against the printed page, not extracted text — the service manual's own text layer badly mis-states the cylinder head hot-torquing caution's temperature figure, and its specifications table drops every decimal point from the clearance figures, so a version of this page built from extracted text alone would have shipped a wrong caution and gibberish clearance values. Connecting rod bolts, valve cover, and intake manifold screws differ between the P216/P218/P220 group and the P224 — those are genuine per-model figures printed side by side in the same table, not a disagreement to resolve; the flywheel capscrew figure (50-55 ft-lb / 67-75 N·m) is one of ten rows Onan prints identically for all four models — only the connecting rod bolts, valve cover, intake manifold screws and the head fasteners split by model group.

Onan P216 / P218 / P220 Manufacturer-published

series Cummins-Onan Performer series, side-valve horizontal twins, commonly fitted to garden tractors of the era. Per the service manual's spec table (965-0762 p.2-1): P216 is 43.3 cu in (710 cc); P218 and P220 share the same 3.250 x 2.875 in bore/stroke, 47.7 cu in (782 cc), differing only in rated output (18 vs 20 HP). Onan's Assembly Torques table (965-0762 p.4-1) groups these three displacements into one torque scope — the P224 uses its own column, see the Onan P224 engine below.
From Onan's Performer Series Engine Service Manual, 965-0762: Assembly Torques Table 1, p.4-1, the head-torque sequence, p.10-17, and the… More about this engine ›

connecting-rod install procedure, p.10-16. Side-valve (L-head) design — there is no rocker arm assembly and therefore no rocker-box torque spec on this engine; the Valve Cover row below is the applicable top-cover fastener. Ignition is solid-state electronic (magnetic trigger ring) with no breaker points, so there is no point-gap spec to set. Ignition timing is a fixed, non-adjustable 20° BTC. Oil capacity is 1.5 qt without the filter (Service Manual p.2-1, Standard Base) or 1.8 qt with it (Operator's Manual p.17, Low Profile Base, footnoted "with filter") — the Service Manual separately lists a 0.3 qt oil filter capacity, and 1.5 + 0.3 = 1.8, so the two documents agree.

Fastener Torque Where it comes from
gearcase cover 8–10 ft-lbHigh
11-14 N·m. Assembly Torques Table 1, Onan 965-0762 p.4-1: "All threads must be clean and lubricated with new engine oil before torquing." No… Why › thread size is printed for this fastener.
rear bearing plate screws 25–27 ft-lbHigh 34-37 N·m. Assembly Torques Table 1, p.4-1.
starter mounting bolts 19–21 ft-lbHigh
25-28 N·m. Assembly Torques Table 1, p.4-1 — this is the mounting-bolt row in the main torque table, a different fastener from the Starter… Why › Assembly Torques teardown table (see the solenoid/brush/through-bolt rows below).
connecting rod bolts 12–14 ft-lbHigh
16-19 N·m. Assembly Torques Table 1, p.4-1. Why › Staged install, p.10-16: "Install one fastener and tighten to 5 ft-lbs (7 Nm). Repeat this for the other fastener. Tighten both fasteners down to the torque specified in ASSEMBLY TORQUES."
flywheel capscrews 50–55 ft-lbHigh
67-75 N·m. Assembly Torques Table 1, p.4-1 — one of ten rows Onan prints identically for all four Performer models; only the connecting rod… Why › bolts, valve cover, intake manifold screws and the head fasteners split by model group.
oil base 18–23 ft-lbHigh 24-31 N·m. Assembly Torques Table 1, p.4-1.
oil pump 7–9 ft-lbHigh 10-12 N·m. Assembly Torques Table 1, p.4-1.
valve cover 1–2 ft-lbHigh
1-3 N·m as printed, Assembly Torques Table 1, p.4-1 — at this low torque the source document itself rounds its N·m column to whole numbers… Why › (1 ft-lb = 1.4 N·m, 2 ft-lb = 2.7 N·m); not an exact conversion. Noticeably lighter than the P224's 4-8 ft-lb valve cover; do not cross-apply.
cylinder head bolts (asbestos gasket) 16–18 ft-lbHigh
22-24 N·m, cold engine only: "Torquing or removing cylinder heads when hot (above 100°F [37°C]) will result in head damage. Why › Allow heads to cool to below 100°F (37°C) before torquing or removing." Staged: "Tighten all bolts to 5 ft-lbs (7 Nm), then 10 ft-lbs (14 Nm), then to the torque specified in ASSEMBLY TORQUES. Recheck all head bolts for correct torque." Figure 28's 9-position sequence (No. 1/LH cylinder) tightens positions 1-2 at the middle row, 3-4 at the upper row, 5-6 at the next row down, 7 at top-center, and 8-9 at the bottom row; No. 2/RH cylinder is the mirror image of that pattern. Recheck torque after the engine has run 50 hours.
cylinder head bolts (graphoil gasket) 14–16 ft-lbHigh
19-22 N·m — same 3-stage procedure (5 ft-lb, then 10 ft-lb, then final) and the same Figure 28 mirrored 9-position sequence as the… Why › asbestos-gasket row above; gasket material is the only variable between the two final figures. Heads must be below 100°F (37°C) before torquing or removing.
intake manifold mounting screws 6–10 ft-lbHigh 8-14 N·m. Assembly Torques Table 1, p.4-1 — a much lighter range than the P224's 20-23 ft-lb; do not cross-apply.
exhaust manifold mounting screws 9–11 ft-lbHigh 12-15 N·m. Assembly Torques Table 1, p.4-1 — same figure on the P224.
other 1/4" cylinder block stud and nuts1/4" 7–9 ft-lbHigh
10-12 N·m. Generic catch-all row, Assembly Torques Table 1, p.4-1 — same figure on the P224. Why › "Refer to the PARTS MANUAL for the location of washers and capscrews."
other 5/16" cylinder block stud and nuts5/16" 8–10 ft-lbHigh 11-14 N·m. Same table — same figure on the P224.
other 3/8" cylinder block stud and nuts3/8" 18–23 ft-lbHigh 24-31 N·m. Same table — same figure on the P224.
solenoid screws (starter assembly) 54 in-lb≈ 4.5 ft-lbHigh 6.1 N·m. Starter Assembly Torques — a SEPARATE "Table 1" from the Assembly Torques table above, Onan 965-0762 p.9-2, an internal starter-teardown torque table.
brush retaining screws (starter assembly) 33 in-lb≈ 2.8 ft-lbHigh 3.7 N·m. Starter Assembly Torques, p.9-2.
through bolts (starter assembly) 51 in-lb≈ 4.3 ft-lbHigh 5.8 N·m. Starter Assembly Torques, p.9-2.
spark plug 11 ft-lbHigh
14 N·m. Only published in the Operator's Manual, p.17 — the Service Manual's own torque table never states a spark plug figure. Why › "To prevent crossthreading the spark plug always thread it in by hand until it seats. Then turn it with a wrench an additional 1/16 turn (22-1/2°). If you have a torque wrench, tighten the spark plugs to 11 lbs-ft (14 N-m)." Applies to all four Performer models. Gap 0.025 in (0.64 mm).

Valve clearance — feeler gauge, not a wrench

  • valve clearance, intake (cold): Not a torque spec -- clearance value: 0.005 in (0.13 mm). Specifications table, Onan 965-0762 p.2-1, same figure for all four models; confirmed again in the Operator's Manual (965-0167 p.17).
  • valve clearance, exhaust (cold): Not a torque spec -- clearance value: 0.013 in (0.33 mm). Same table as the intake row above, p.2-1.
3 specs not published — oil drain plug, blower housing, crankshaft / camshaft gear What we found ›
  • oil drain plugGAP: no oil drain plug torque figure is printed in either the Service Manual's Assembly Torques table or the Operator's Manual.
  • blower housingGAP: the blower housing is referenced only as an assembly step in the Service Manual, never given its own torque value.
  • crankshaft / camshaft gearGAP: crankshaft and camshaft gears are pressed and keyed rather than bolted per the Service Manual's text, so no torque-table row exists for them.

Onan P224983cc Manufacturer-published

series Cummins-Onan Performer series, side-valve horizontal twin, commonly fitted to garden tractors of the era; the largest of the four Performer displacements (59.7 cu in / 983 cc per the service manual's spec table, p.2-1), sharing most fittings with the P216/P218/P220 but on its own Assembly Torques column (965-0762 p.4-1) for connecting rod bolts, valve cover, head fasteners, and intake manifold screws.
From Onan's Performer Series Engine Service Manual, 965-0762: Assembly Torques Table 1, p.4-1, the head-torque sequence, p.10-18, and the… More about this engine ›

connecting-rod install procedure, p.10-16. Side-valve (L-head) design — there is no rocker arm assembly and therefore no rocker-box torque spec on this engine; the Valve Cover row below is the applicable top-cover fastener. Ignition is solid-state electronic (magnetic trigger ring) with no breaker points, so there is no point-gap spec to set. Ignition timing is a fixed, non-adjustable 20° BTC. Oil capacity is 1.5 qt without the filter (Service Manual p.2-1, Standard Base) or 1.8 qt with it (Operator's Manual p.17, Low Profile Base, footnoted "with filter") — the Service Manual separately lists a 0.3 qt oil filter capacity, and 1.5 + 0.3 = 1.8, so the two documents agree.

Fastener Torque Where it comes from
gearcase cover 8–10 ft-lbHigh 11-14 N·m. Assembly Torques Table 1, Onan 965-0762 p.4-1 — same figure on the P216/P218/P220.
rear bearing plate screws 25–27 ft-lbHigh 34-37 N·m. Assembly Torques Table 1, p.4-1 — same figure on the P216/P218/P220.
starter mounting bolts 19–21 ft-lbHigh
25-28 N·m. Assembly Torques Table 1, p.4-1 — this is the mounting-bolt row in the main torque table, a different fastener from the Starter… Why › Assembly Torques teardown table (see the solenoid/brush/through-bolt rows below).
connecting rod bolts 27–29 ft-lbHigh
37-39 N·m — noticeably higher than the P216/P218/P220's 12-14 ft-lb; do not cross-apply. Why › Assembly Torques Table 1, p.4-1. Install procedure, p.10-16: "Install and tighten the nuts evenly in steps, to the torque specified in ASSEMBLY TORQUES." (The manual's own procedure text calls these fasteners "nuts" even though the torque table lists the row as "Connecting Rod Bolts.")
flywheel capscrews 50–55 ft-lbHigh
67-75 N·m. Assembly Torques Table 1, p.4-1 — one of ten rows Onan prints identically for all four Performer models; only the connecting rod… Why › bolts, valve cover, intake manifold screws and the head fasteners split by model group.
oil base 18–23 ft-lbHigh 24-31 N·m. Assembly Torques Table 1, p.4-1 — same figure on the P216/P218/P220.
oil pump 7–9 ft-lbHigh 10-12 N·m. Assembly Torques Table 1, p.4-1 — same figure on the P216/P218/P220.
valve cover 4–8 ft-lbHigh
5-11 N·m as printed — at this low torque the source document itself rounds its N·m column to whole numbers (4 ft-lb = 5.4 N·m, 8 ft-lb =… Why › 10.8 N·m); not an exact conversion. Noticeably heavier than the P216/P218/P220's 1-2 ft-lb valve cover; do not cross-apply. Assembly Torques Table 1, p.4-1.
cylinder head nuts (with compression washers) 14 ft-lbHigh
19 N·m, single value as printed (not a range), cold engine only: "Torquing or removing cylinder heads when hot (above 100°F [37°C]) will… Why › result in head damage. Allow heads to cool to below 100°F (37°C) before torquing or removing." Two compression washers per stud sandwich outer-edge-only contact: "Install a flat washer, two compression washers, and nut on each of the top six studs... When properly installed, only the outside edges of the compression washers will be in contact with each other. Install a flat washer and nut on each of the four bottom studs." "Over torquing nuts can cause engine damage. Do not over torque nuts." Staged: 5 ft-lb, then 10 ft-lb, then this final figure. Figure 30's 10-position sequence (No. 1/LH cylinder) works from the center outward: positions 1-2 are the middle row (closest to the head center), 3-4 the row above it, 5-6 the row below it, 7-8 the top row, and 9-10 the bottom row last; No. 2/RH cylinder is the mirror image. Positions 1-4 and 7-8 are the six long studs that take the compression washers; positions 5-6 and 9-10 are the four short bottom studs (flat washer and nut). Recheck torque after the engine has run 50 hours.
cylinder head nuts (without compression washers) 17 ft-lbHigh
23 N·m, single value as printed (not a range) — the applicable figure when the compression-washer stack is not used. Why › Same staged procedure, Figure 30 sequence, and 100°F (37°C) cool-head caution as the row above.
intake manifold mounting screws 20–23 ft-lbHigh 27-31 N·m. Assembly Torques Table 1, p.4-1 — a much heavier range than the P216/P218/P220's 6-10 ft-lb; do not cross-apply.
exhaust manifold mounting screws 9–11 ft-lbHigh 12-15 N·m. Assembly Torques Table 1, p.4-1 — same figure on the P216/P218/P220.
other 1/4" cylinder block stud and nuts1/4" 7–9 ft-lbHigh
10-12 N·m. Generic catch-all row, Assembly Torques Table 1, p.4-1 — same figure on the P216/P218/P220. Why › "Refer to the PARTS MANUAL for the location of washers and capscrews."
other 5/16" cylinder block stud and nuts5/16" 8–10 ft-lbHigh 11-14 N·m. Same table — same figure on the P216/P218/P220.
other 3/8" cylinder block stud and nuts3/8" 18–23 ft-lbHigh 24-31 N·m. Same table — same figure on the P216/P218/P220.
solenoid screws (starter assembly) 54 in-lb≈ 4.5 ft-lbHigh 6.1 N·m. Starter Assembly Torques — a SEPARATE "Table 1" from the Assembly Torques table above, Onan 965-0762 p.9-2, an internal starter-teardown torque table.
brush retaining screws (starter assembly) 33 in-lb≈ 2.8 ft-lbHigh 3.7 N·m. Starter Assembly Torques, p.9-2.
through bolts (starter assembly) 51 in-lb≈ 4.3 ft-lbHigh 5.8 N·m. Starter Assembly Torques, p.9-2.
spark plug 11 ft-lbHigh
14 N·m. Only published in the Operator's Manual, p.17 — the Service Manual's own torque table never states a spark plug figure. Why › "To prevent crossthreading the spark plug always thread it in by hand until it seats. Then turn it with a wrench an additional 1/16 turn (22-1/2°). If you have a torque wrench, tighten the spark plugs to 11 lbs-ft (14 N-m)." Applies to all four Performer models. Gap 0.025 in (0.64 mm).

Valve clearance — feeler gauge, not a wrench

  • valve clearance, intake (cold): Not a torque spec -- clearance value: 0.005 in (0.13 mm). Specifications table, Onan 965-0762 p.2-1, same figure for all four models; confirmed again in the Operator's Manual (965-0167 p.17).
  • valve clearance, exhaust (cold): Not a torque spec -- clearance value: 0.013 in (0.33 mm). Same table as the intake row above, p.2-1.
3 specs not published — oil drain plug, blower housing, crankshaft / camshaft gear What we found ›
  • oil drain plugGAP: no oil drain plug torque figure is printed in either the Service Manual's Assembly Torques table or the Operator's Manual.
  • blower housingGAP: the blower housing is referenced only as an assembly step in the Service Manual, never given its own torque value.
  • crankshaft / camshaft gearGAP: crankshaft and camshaft gears are pressed and keyed rather than bolted per the Service Manual's text, so no torque-table row exists for them.

What is the cylinder head bolt torque on an Onan P216, P218 or P220?

16-18 ft-lb (22-24 N·m) with an asbestos head gasket, or 14-16 ft-lb (19-22 N·m) with a graphoil gasket — Onan's Performer Series Service Manual (965-0762) prints two figures because the gasket material changes the clamp load needed. Reach either final figure in three stages: "Tighten all bolts to 5 ft-lbs (7 Nm), then 10 ft-lbs (14 Nm), then to the torque specified in ASSEMBLY TORQUES." Follow the 9-position sequence in Figure 28 (p.10-17), which is mirrored between the two cylinders, and only torque a cooled head: "Torquing or removing cylinder heads when hot (above 100°F [37°C]) will result in head damage. Allow heads to cool to below 100°F (37°C) before torquing or removing."

What is the head torque on an Onan P224?

Cylinder head NUTS, not bolts, on the P224 — 14 ft-lb (19 N·m) with the two compression washers installed on each of the top six long studs, or 17 ft-lb (23 N·m) without them. "Over torquing nuts can cause engine damage. Do not over torque nuts." Reach the final figure the same staged way as the smaller engines — 5 ft-lb, then 10 ft-lb, then final — following the 10-position sequence in Figure 30 (p.10-18), and only with the heads cooled below 100°F (37°C).

Is the Onan Performer flywheel capscrew torque the same on all four engines?

Yes — 50-55 ft-lb (67-75 N·m) is one of ten rows Onan's Assembly Torques table (p.4-1) prints identically for the P216, P218, P220 and P224; only the connecting rod bolts, valve cover, intake manifold screws and the head fasteners split by model group.

What is the spark plug torque on an Onan Performer engine?

Applies to all four models: "If you have a torque wrench, tighten the spark plugs to 11 lbs-ft (14 N-m)." This figure is only published in Onan's Operator's Manual (965-0167, p.17) — the Service Manual's own torque table never states a spark plug figure. Gap is 0.025 in (0.64 mm).

Why do the connecting rod bolt and intake manifold torques differ between the small Performer engines and the P224?

Because Onan's own Assembly Torques table (p.4-1) prints them differently for the two groups: connecting rod bolts are 12-14 ft-lb on the P216/P218/P220 but 27-29 ft-lb on the P224; intake manifold mounting screws are 6-10 ft-lb versus 20-23 ft-lb. These are genuine per-model figures printed side by side in the same table, not a disagreement — never carry a P216/P218/P220 number onto a P224 or vice versa.

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