E30 M3 Euro Exhaust Cam Sprocket Installation

by: Bob Stommel (
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The Euro cam gear moves the camshaft 3 degrees. This produces more mid-range torque with just a little loss of high-end torque. For the street, the E30 M3 is very weak in the mid-range, so loss of some torque at over 6000 rpm is worth it.

(This note from Ed Hall: The same gear will also work on the 87-88 M-5 and 6's I installed one on my 87 M-6 and reduced the 60-80 time in third by .2 plus and in all other gears as well. There seem to be 2 schools of thought some install a gear that retards the timing where as the factory gear of course advances; most of the people who go with the retard that I have spoken with, are disapointed and those that go with the advance are pleased.)

Parts needed:

  • Euro exhaust cam sprocket
  • Cam sprocket lockplate (get two if you decide to replace the bolts on the intake cam sprocket -- see step 18 below)
  • Six M6X16 bolts (see note on bolt hardness in step 18 below; get 12 bolts if you decide to replace the ones on the intake cam sprocket)
  • Timing chain tensioner piston and cylinder (housing) (sold in a set)
  • Crush washers (2) and small rubber O-ring for timing chain tensioner housing
  • Timing chain tensioner spring
  • Outer O-ring seal and internal seal for distributor housing
  • Outer O-ring seal for the intake camshaft access plate -- if you decide to replace the bolts on the intake cam sprocket (see step 18 below)
  • Valve cover gaskets (including the inside ones around the spark plug holes)

Optional parts:

  • Spark plugs (Bosch X5DC -- gapped to 0.7 mm)
  • Distributor cap
  • Distributor rotor


1. Put car in neutral and apply emergency brake.

2. Remove black plastic cover from distributor cap (held onto distributor cap with three 8mm bolts).

3. Remove two 10mm cap nuts that hold ignition wire holder to valve cover.

 4. Pull up on each spark plug wire boot to loosen it from the spark plugs (don't try to pull boots out yet).

 5. Label the ignition wires with their cylinder numbers and then the wires off the distributor cap and ignition coil.

 6. Pull entire ignition wire set off engine. This is a good time to inspect your ignition wires. The plastic wire casing can be disassembled by first removing the two Phillips screws on the bottom of the holder housing and then pulling the side tabs apart. My wires were replaced about 10,000 miles ago and there were already some signs of the wires being pinched inside the holder. I opted to leave the holder off for reinstallation. Instead, I banded the wires together with zip ties and at each zip tie location, I wrapped each wire separately with heat-resistant tape before banding the wire together. If you want to be extra careful, you will need to find a way to keep the wires away from the lower passenger-side edge of the valve cover on reinstallation. I fabricated a small looped bracket around the wires and bolted it to the original right-side bolt on the valve cover for the wire holder. This gives the wires about a 1/4 inch clearance off the valve cover.

 7. Remove spark plugs. Stuff small rags into each spark plug access hole to prevent anything from falling into the engine. Reinstallation: Tightening torque for the spark plugs is 18-20 ft lbs. Use an anti-seize compound (such as Lubro Moly LM 508 Anti-Seize Compound) on the spark plug threads on reinstallation.

8. Remove distributor cap from housing (held on by three long, thin 8mm bolts that extend from the distributor cap; they do not separate from the distributor cap).

9. Remove ignition rotor from housing (held in place by three 3mm hex head screws that do not separate from the rotor).

10. Remove the triangular rotor base from the front of the camshaft. It is held in place by a single 6mm hex head bolt.

11. Remove the 10mm cap nut holding the coolant sensor wires to the distributor housing and then remove distributor housing from side of cylinder head (held in place by three 10 mm nuts with wave washers). It takes quite a bit of wiggling to get the housing off the head and camshaft. Reinstallation: Replace the inside and outside seals on the housing before reinstallation. The inner seal can be tapped out with a socket from the inside out (carefully note the position of the seal before you remove it!). Use the same socket to tap the new inner seal into place. Coat the inside lip of the inner seal with oil before reinstallation of the distributor housing onto the cylinder head.

 12. Remove breather hose from top driver-side corner of valve cover.

 13. Remove valve cover cap nuts and take off valve cover. Get new valve cover gasket and round inside gaskets. This is a good time to sand and repaint your valve cover if the paint is chipping. (Mine was in pretty bad shape.) I used Eastwood's Black Wrinkle Finish Paint, Part No. 1230. I don't know how long it will last, but Eastwood says it will withstand engine temperatures on a valve cover. Reinstallation: Tightening torque for the valve cover cap nuts is 9 ft. lbs.

 14. Using a 36mm socket on the front crankshaft nut (inside crankshaft pulley on lower part of timing case), turn the engine over until the notch on the crankshaft pulley line up with the pointer on the timing cover AND the notches on the right side of the camshafts line up with the indentations in the top of the camshaft bearing caps. The engine will now be at top dead center. If all the reference points don't line up, rotate the engine another revolution until they do.

15. Remove the timing chain guide rail from the top of the timing chain. It is bolted to the cylinder head by two 6mm hex head bolts.

 16. Remove the timing chain tensioner. It is attached to the lower right corner of the cylinder head below the metal coolant tube as you look at it from the passenger side. There are three sections to it. The outer bolt is a 13mm bleeder nipple (no tightening torque specified). The second section toward the engine releases the timing tensioner piston and is removed with a 19 mm wrench or socket (tightening torque is 29 ft. lbs). The piston and spring will come flying out with lots of oil when you remove it. The third section is bolted to the head and is a cylinder housing for the tensioner piston. The housing requires a 32 mm wrench or socket for removal (tightening torque is 36 ft. lbs.). Check the piston and cylinder housing for wear and scoring. The housing and piston are only sold as a set because the machined tolerances are very tight. Don't just replace one or the other. It's also a good idea to replace the tensioner spring while you are at it -- the spring can look fine and still be the correct length (159 mm), yet have weakened below its original spring rate. Reinstallation: Make sure the tapered (conical wound) end of the tensioner spring is facing toward the outer nut -- the flat end of the spring faces the tensioner piston. Before reinstalling the tensioner piston, rotate the engine so that the timing chain is tight between the two cam sprockets (no slack) and make sure you install the piston with the notch (groove) in the vertical position. It takes a lot of muscle to get the spring compressed back into the cylinder housing. (If you can find a way to do it, after reinstallation of all the tensioner piston parts, open the 13mm bleed nipple and pump engine oil into the nipple until it runs out of the nipple. This pre-loads the tensioner piston with oil.)

17. The exhaust camshaft sprocket is held to the camshaft by six 10mm bolts that are secured by a lock plate. Push the ends of the lockplate away from each of the bolts and remove the bolts from the sprocket. BE CAREFUL NOT TO LET THE BOLTS FALL DOWN THE INSIDE OF THE TIMING COVER INTO THE ENGINE! I held a magnet near each bolt as I removed it to make sure nothing fell into the engine. You may have to rotate the engine (with the 36mm socket on the crankshaft nut) to get access to each of the six bolts holding the sprocket to the end of the camshaft). After the bolts and lockplate are removed, pull the sprocket end plate/spindle (the piece that rotated inside the distributor cover housing) off the end of the camshaft. You will then be able to remove the OEM sprocket from the camshaft. Lift the timing chain and pull the sprocket out from under the front of the chain.

18. Install the Euro cam sprocket, the sprocket end plate/spindle, and a new lockplate. Before you install the cam sprocket, you will need to rotate the exhaust camshaft slightly counter-clockwise (toward the passenger side) in order to get the pin on the end of the camshaft positioned to take the Euro sprocket (the Euro sprocket is 3 degrees offset from the original one). I placed a socket extension against a thick towel on one of the camshaft lobes and gently tapped it to move the camshaft. Before you install the new lockplate on the end of the spindle, use a flat-nosed pliers to gently bend the inside edges of the plate upward. This will allow you to get a small screwdriver under the edges after it is bolted on, so that you can lock the plate edges against the cam sprocket bolts. The original cam sprocket bolts are 8.8 hardness. I found a local supplier that had the same size bolt in a 10.9 hardness. The 10.9 hardness bolts can be torqued to 15 ft. lbs. The specified tightening torque for the 8.8 hardness bolts is 7 ft. lbs. If you can find the harder bolts, you might also want to replace the ones for the intake cam sprocket. The access cover for the intake camshaft sprocket is on the front of the cylinder head and is held in place by two 10mm cap nuts. Once the cover is removed, the procedure for replacing the sprocket bolts is the same. Make sure to use a new lockplate. Replace the outer O-ring on the access cover before reinstallation.

19. Rotate the engine so that it's at top dead center (notch in crankshaft pulley matches pointer on engine and both notches on the tops of the camshafts are aligned with the notches in the cam bearing caps. The notch in the Euro exhaust cam will be a few millimeters to the right (toward passenger side) of the original position due to the 3 degree offset. If everything is not lined up properly, recheck your work.

20. If it's been a while since you did so, this would be a good time to adjust the valves.

21. Reinstall everything in reverse order of above.

22. Restart the engine and let it idle for about 10 minutes. There may be some timing chain noise during this time until the tensioner piston gets pumped back up with oil pressure. Test drive the car and check for any oil leaks. If your engine had some timing chain noise before, it should be much quieter now. You might also want to change the oil and oil filter just in case some debris fell into the crankcase.

Bob Stommel

Indianapolis, IN

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