Spec Sheet

Cylinder Head Installation Procedure

Engine Block Preparation:

• Clean out the cylinder head bolt holes in the engine block by spraying brake cleaner or carb cleaner (with extended nozzle tip) into the holes. Use a rag over the holes to shield cleaner from spraying into your eyes.
• Use a flat sharpening stone (like one for sharpening knives) to smooth out the block deck. Go over the block surface in circular motions with the stone while keeping it lubricated with WD-40.
• Clean the deck surface of the engine block with brake cleaner or carb cleaner.
• Lay the cylinder head gasket of your choice.
• Install the two cylinder head dowels into the engine block. We recommend replacing the dowels with new parts when possible.
• Check that the crankshaft and camshaft are at top dead center and mate the cylinder head to the engine block. Take your time to ensure you don't damage the cylinder head deck surface or valves during this process.
• If using OE-style cylinder head bolts, make sure they are NEW. You cannot reuse your original bolts, but you WILL need to reuse your original head bolt washers. Coat the bolts lightly with engine oil and install the cylinder head bolts. The torque specifications and sequence are also shown on this page.

Engine & Cylinder Head Break-In Process

Notes & Instructions:

• All rebuilt cylinder heads and engines are shipped with the valve clearance pre-adjusted and the camshaft set to top dead center. You will need to install your own rear water neck and oil transfer tube. For customers who have purchased a rebuilt cylinder head only, we recommend checking the valve clearances again before initial startup once the cylinder head is installed on the engine block.
• Run in the engine at 2,000 RPM for approximately 20 minutes on first startup to break in the camshaft and rocker arms. Do not skip this step. We recommend using Motul Break-In Oil for this process. (For M20 Touring, Super Sport, or Race engines, this step has already been completed in-house by BimmerHeads.)
• Let the engine cool completely overnight (if possible) and re-adjust the valve clearance. Valve clearances will change as the valvetrain breaks in. After approximately 500–1,000 miles have been put on the engine, adjust the valve clearance again and change the engine oil. (We recommend performing valve adjustments on completely cold engines to achieve the most consistent results.)
• We highly recommend using a conventional engine oil with a high zinc content for these engines, such as the Motul Classic 20W-50. Using the proper engine oil is the best way to protect your investment.

Valve Clearance Specifications

These Specs Apply To A Cold Engine Only:

• M10 Engine: 0.008 inches (0.20 mm)
• M20 Engine: 0.010 inches (0.25 mm)
• M30 Engine: 0.012 inches (0.30 mm)
• S14 Engine: 0.011 to 0.013 inches (0.28 mm to 0.33 mm)
• S38 Engine: 0.011 to 0.013 inches (0.28 mm to 0.33 mm)

Torque Specifications

OE Head Bolts (Lube lightly with engine oil):

• M10 Engine:
  • Step 1: Torque to 25 to 33 ft-lbs (35 to 45 Nm)
  • Step 2: Torque to 43 to 47 ft-lbs (60 to 65 Nm)
  • Step 3: Torque to 49 to 52 ft-lbs (68 to 72 Nm)
  • After heat cycle, re-torque cold to 52 ft-lbs (72 Nm)
• M20 Engine:
  • Step 1: Torque to 22 ft-lbs (30 Nm)
  • Step 2: Tighten bolts 90 degrees
  • Step 3: Tighten bolts an additional 90 degrees
• M30 Engine:
  • Step 1: Torque to 25 to 33 ft-lbs (35 to 45 Nm)
  • Step 2: Torque to 43 to 47 ft-lbs (60 to 65 Nm)
  • Step 3: Torque to 49 to 52 ft-lbs (68 to 72 Nm)
  • After heat cycle, re-torque cold to 52 ft-lbs (72 Nm)
• S14 Engine:
  • Step 1: Torque to 36 ft-lbs (50 Nm)
  • Step 2: Torque to 58 ft-lbs (80 Nm)
  • Step 3: Torque to 72 ft-lbs (100 Nm)
• S38 Engine:
  • Step 1: Torque to 14.5 ft-lbs (20 Nm)
  • Step 2: Tighten bolts 60 degrees
  • Step 3: Tighten bolts an additional 70 degrees
• S50 & S52 Engines:
  • Step 1: Torque to 22 ft-lbs (30 Nm)
  • Step 2: Tighten bolts 90 degrees
  • Step 3: Tighten bolts an additional 90 degrees

OE Rod Bolts (Lube lightly with engine oil):

• M10 Engine: 38 to 42 ft-lbs (52 to 57 Nm)
• M20 Engine: 14.5 ft-lbs (20 Nm) + 70 degrees
• M30 Engine: 38 to 42 ft-lbs (52 to 57 Nm)
• S14 Engine: 11 ft-lbs (15 Nm) + 22 ft-lbs (30 Nm) + 60 degrees
• S38 Engine: 11 ft-lbs (15 Nm) + 22 ft-lbs (30 Nm) + 60 degrees
• S50 & S52 Engines: 14.5 ft-lbs (20 Nm) + 70 degrees

OE Main Bolts (Lube lightly with engine oil):

• M10 Engine: 43 to 46 ft-lbs (58 to 63 Nm)
• M20 Engine: 43 to 46 ft-lbs (58 to 63 Nm)
• M30 Engine: 43 to 46 ft-lbs (58 to 63 Nm)
• S14 Engine: 43 to 46 ft-lbs (58 to 63 Nm)
• S38 Engine: 43 to 46 ft-lbs (58 to 63 Nm)
• S50 & S52 Engines: 43 to 46 ft-lbs (58 to 63 Nm)

ARP Head Studs (With ARP lube):

• M10 Engine: 90 ft-lbs in three equal steps
• M20 Engine: 70 ft-lbs in three equal steps
• M30 Engine: 90 ft-lbs in three equal steps
• S14 Engine: 95 ft-lbs in three equal steps
• S38 Engine: 95 ft-lbs in three equal steps
• S50 & S52 Engines: 75 ft-lbs in three equal steps

ARP Connecting Rod Bolts:

• M10 Engine: 50 ft-lbs (with ARP lube)
• M20 Engine: 40 ft-lbs (with ARP lube)
• M30 Engine: 50 ft-lbs (with ARP lube)
• S14 Engine: 70 ft-lbs (with ARP lube)
• S38 Engine: 70 ft-lbs (with ARP lube)
• S50 & S52 Engines: 40 ft-lbs (with ARP lube)
• M20 Molnar H-Beam: 25 ft-lbs + 55 degrees (with Molnar lube)
• S50 & S52 Molnar H-Beam: 25 ft-lbs + 55 degrees (with Molnar lube)

ARP Main Studs (With ARP lube):

• M10 Engine: 60 ft-lbs in three equal steps
• M20 Engine: 60 ft-lbs in three equal steps
• M30 Engine: 60 ft-lbs in three equal steps
• S14 Engine: 60 ft-lbs in three equal steps
• S38 Engine: 60 ft-lbs in three equal steps
• S50 & S52 Engines: 60 ft-lbs in three equal steps

ARP Main Bolts (by BimmerHeads):

• M20 Engine: 60 ft-lbs in three equal steps (with ARP lube)
• S50 & S52 Engines: 60 ft-lbs in three equal steps (with ARP lube)

Cylinder Head Bolt Torque Sequence

M10 & S14:

M20, M30, S38, S50, & S52: