Warner Engine Handbook:

Final Assembly, Timing and Testing

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Section XI - Final Assembly, Timing and Testing

1.  General

a.  Observe the assembly precautions listed in Section III of this handbook as well as those listed below.

b.  If the engine is to stand for any length of time before final assembly is completed, all steel parts both inside and outside must be covered with oil to prevent corrosion.

c.  Use extreme care to prevent dirt, dust, cotterpins, lockwire, nuts, bolts, washers and any particles or parts from falling inside the engine.  Keep all spark plug holes, intake pipe openings, carburetor inlet openings, and all other parts covered until the installation of the respective parts or covers.

d.  Observe the following precautions when using a torque wrench:

(1) Make sure that no part of the wrench binds on any part of the engine.

(2) Install the wrench in such a position that the nut or screw may be pulled up to the required torque without interruption.

(3) The torque load should be applied until the nut or screw has ceased to turn.  This may require several seconds from the time that the indicator reaches the required torque value.

e. New gaskets and packings will be installed where they are required, replacing those which were removed at disassembly.  All mating gears, shafts and bearings will be adequately oiled prior to installation.  All safety wiring, hose clamps and cotter pins will be installed where necessary, following the final assembly of each part.

2.  Final Assembly of the Major Sub-Assemblies


(1) Place and lock mounting plate of engine assembly stand in a vertical position.

(2) Attach induction housing assembly to mounting plate with four 5/16" bolts using flat washers under the retaining bolts to prevent damaging the front face of the mounting lugs.


(1) Check to see that the six crankcase bolts and their washers are in place, and the crankcase to induction housing gasket is not omitted.

(2) Attach crankcase rear section to front side of induction housing.  Rotate the cam drive shaft and tachometer shaft if necessary, until the gear teeth on the shaft mesh with the gear teeth on the cam ring.

(3) Secure crankcase rear section to induction housing by installing washers and nuts on the studs that protrude through the rear side of the induction housing.

(4) Tighten nuts with desired torque and safety each nut with cotter pin.


(1) Rotate and lock mounting plate of engine assembly stand in a horizontal position, i.e., the rear of the induction housing will face the floor.

(2) Lightly tap down any crankcase bolts that may protrude beyond the parting surface of the crankcase rear section


Do not try to drive back stud between cylinder Nos. 4 and 5.

(3) Install crankshaft and crankcase front section assembly into place on the crankshaft rear section.  Care must be exercised in guiding the crankcase front section of the stud between cylinder Nos. 4 and 5. (Note: No. 1 cylinder is diametrically opposite to this stud).

(4) If the crankcase front section does not immediately seat itself against the rear section, tap the crankcase front section with a rawhide mallet and level the front section until it is seated.

(5) Using driving tube, drive on the thrust nut and bearing until the front section is well seated against the rear section.


Never attempt to pull the crankcase down by means of the crankcase bolts and nuts.

(6) After the crankcase sections are firmly in place, push the crankcase bolts into the front section and install the flat washers and retaining nuts on the bolts and stud.  Tighten nuts evenly and gradually with the desired torque as specified in the table of limits.  Safety crankcase nuts with cotterpins.


(1) Using the crankshaft turning bar No. FA-182 and thrust nut wrench No. FA-274 in a manner similar to that shown in Figure 7, tighten the thrust bearing nut very tightly (see table of limits).  This will prevent wear and damage to the crankshaft when the engine is operated.


(1) Tap the outer race of the thrust bearing until the bearing is well seated against the shoulder of the crankcase sleeve.

(2) Place the thrust cover over the crankshaft into place on its crankcase mating flange with the cast-in word "top" nearest the No. 1 cylinder pad.

(3) Hold the thrust cover firmly against the thrust bearing and check with a feeler gage the clearance between the cover and the crankcase.

(4) After the clearance is obtained, determine which one of combination of thrust bearing cover gaskets are to be used that will have a combined thickness of .004" to .006" less than the space measured with the feeler.  This will cause the outer race of the thrust bearing to be held firmly and kept from rotating when the thrust cover and gaskets are installed in place.  Thrust cover gaskets are available in thickness of .003" and .005".

(5) Install gasket or gaskets and thrust cover.  Secure cover in place with flat washers, lock washers and retaining nuts.  Tighten nuts with required torque as established in table of limits.



The three top rings on each piston should be installed in such a manner that the gaps of all three rings are approximately 120 apart.

(1) Install piston ring clamp No. FA-46-1 over the three top piston rings and compress the rings.

(2) Place cylinder on a bench and install the piston into the end of the cylinder, so that the stamped cylinder number on the head of the piston is forward; i.e., toward the propeller end of the engine.

(3) Push the piston into the cylinder just far enough to cover the piston rings.  This will leave the piston pin hole outside of the cylinder skirt, and will allow the mechanic to install the piston pin into the piston and connecting rod bushing when assembling the cylinders to the crankcase.

(4) Install the remaining pistons into their respective cylinders in accordance with the method outlined above.


(1) Install new cylinder base gaskets or "O" ring packings (depending on Engine model) and turn the crankshaft to a position in which the connecting rod of No. 1 cylinder extends the maximum distance outside of the cylinder flange.

Editor's Note:  There are numerous Service Bulletins post-dating this manual that dictate replacement of all gaskets and cylinders with the O-ring style cylinder base gaskets.  Don't assemble an engine using anything but the O-ring style gaskets, since apparently the gasket crush on non-O-ring gaskets was causing the cylinders to work up and down on the mounting studs, which would ultimately break off the studs.

(2) Holding cylinder assembly as shown in Figure 22 line up the piston hole in the piston with the bushing in the rod and inset the piston pin with the stamped end of the pin facing toward the propeller end of the engine.

<< INSERT FIGURE 22, Page 68 >>

(3) Squeeze the fourth ring with fingers and push cylinder just over the ring.

(4) Slip the spring, washer and new packing, in the order named, over the long end of the push rod tube.

(5) Insert a push rod in each of the push rod tubes.

(6) Holding a push rod tube assembly in each hand, push the cylinder into place on the crankcase with the body, at the same time guiding the two push rod tubes into place.


The long end of the push rod with the spring, washer and packing is at the cylinder.

(7) Install and tighten cylinder base nuts using wrench No. FA-33-A.  Tighten nuts with desired torque as outlined in table of limits.


Do not exceed torque limitations.

(8) Next, install and tighten palnuts on the cylinder base retaining studs with the smooth face against the plain nut.  Do not tighten less than 60 or more than 90 from the point where they contact the cylinder base retaining nuts as the threads on the studs may be damaged.

(9) Install the remaining cylinders, using the same procedure as outlined above.

(10) On the intake pipe install, in the order named, the spring, gland and new packing.

(11) Install new gaskets on the intake flange of the cylinder.

(12) Insert the end of the induction housing tube into the induction housing opening, and push the flanged end into place over the studs.

(13) Install a plain washer, lockwasher and nut on the inside stud of the intake pipe flange and an ignition wire clip, lockwasher and nut on the outside stud.  (Ignition cable clip is not used when breeze shielding is installed).

(14) Tighten the intake pipe nuts to the required torque.


The ignition cable clips must be in a position with the open end facing out.


(1) Rotate the lock the engine mounting plate of the assembly stand so that the engine is in a normal or flight position.

(2) Install timing disc FA-16-1 and pointer No. FA-16-L to the engine as shown in figure 23.  The timing disc must be installed with the omitted spline over the spline blocking screw which is installed on the top and front of the crankshaft when crankshaft is in "Top Center No. 1 Cylinder" position.  The pointer is attached to the front cylinder base studs of No. 1 cylinder.

<< INSERT FIGURE 23, Page 69 >>


The proper location of the timing disc on the crankshaft may be checked by the use of a top dead center indicator or by observation of the piston travel in cylinder No. 1.  The piston in No. 1 cylinder must be in the top dead center position when the "0" and "TC-1" markings on the disc line up with the pointer.

(3) With the No. 1 piston at top dead center, turn the cam drive idler shaft with a wrench on the tongue of the pump drive coupling until both valves of No. 1 cylinder are closed while the intake valve of No. 7 cylinder and the exhaust valve of No. 2 are both approximately half open.

(4) Using the 5/8 and 3/4 open end wrench FA-39, a screw driver and feeler gages, adjust cylinder No. 1 intake and exhaust valve clearances to .027 inches between the rocker arm roller and the end of the valve stem.

(5) Turn the timing disc to 10 before top dead center of No. 1 cylinder.

(6) Slowly turn the cam drive idler shaft anti-clockwise until No. 1 intake valve starts to open.  This can be determined by inserting a .0015 inch feeler gage between the rocker arm roller and the end of the valve stem.  When the valve starts to open, the feeler will begin to stick.

(7) Install the cam and magneto drive shaft, engaging slot in the shaft with the tongue in the end of the crankshaft.

(8) Immediately install the gear on the cam drive idler shaft hub by rotating gear until a set of three holes in the gear line up with three holes in the hub.


Do not move either the hub or cam and magneto drive shaft during this operation.

(9) Install the three gear retaining bolts.


Do not fully tighten the bolts at this stage of the timing.  The valve opening and closing points should be obtained for the four groups of lobes on the cam ring by repeating the readings on cylinder No. 1 while rotating the crankshaft 8 full turns in direction of propeller rotation.  The readings for each group of cam lobes should be taken in the following sequence:

  1. Intake opens.
  2. Exhaust closes.
  3. Intake closes.
  4. Exhaust opens.

The approximate average values of the four sets of readings should be used to determine the amount of advance or retard required to time the valves.

(10) The design timing of the engine is as follows:

Exhaust opens 60 before bottom center
Intake opens 10 before top center
Exhaust closes 10 after top center
Intake closes 60 after bottom center



From the above values it can be seen that both valves remain open during 250 degrees of the crankshaft rotation.

(11) Due to a summation of factors (listed below) which effect timing, variations from the design timing can be expected, and the valves should be timed accordingly.

(a) At the point of valve opening and valve closing, the cam lobes are equipped with ramps which give very little valve lift but for small variations of the contours show large variations in readings for valve timing, since they are magnified 8:1 through the timing gears.


The variations outlined above existing at the cam ramp which manifest themselves in rather large timing variations do not affect the power output of the engine since their influence on the effective valve lift is negligible.

(b) The timing values obtained will be affected by the accuracy with which the tappets are set at .027".  A decrease in this clearance will result in the valves remaining open longer than 250 degrees of crankshaft rotations, and an increase in this clearance will result in a reduction of the time during which the valves are open as compared to 250 degrees of crankshaft rotation.

(c) If, when timing, the range of valve opening is found to be more or less than 250 degrees this can be attributed to the accuracy of the .027" tappet setting plus the manufacturing limits on the cam, and if it should cause difficulty, it is permissible to increase or reduce the tappet settings the slight amount required to obtain the 250 degrees valve opening.

(d) In comparing the timing values obtained with the design timing values and considering the necessary timing changes, it must be kept in mind that advancing the ignition timing increase the value in degrees of the "exhaust opens" and "intake opens" points and reduces the values of the "exhaust closes" and "intake closes" points.  Conversely, retarding the timing decreases the values in degrees of the "exhaust opens" and "intake opens" points and increases the values for the "exhaust closes" and "intake closes" points.

(12) If it is found necessary to advance or retard the observed actual timing, proceed as follows:

(a) Return the timing disc to cylinder No. 1 top dead center of the firing stroke.

(b) Remove the three gear retaining bolts and gear from the cam drive idler shaft.

(c) Advance or retard the timing disc the required number of degrees.

(d) Reinstall the gear and three bolts as outlined above for preliminary timing.

(e) Recheck the timing as previously outlined.

(f) If timing is found satisfactory, tighten the three bolts to the required torque and lockwire.


Upon completion of the valve timing, immediately proceed with the next operation of installing the gearcase as outlined below, so that the am and magneto drive shaft cannot be pulled out resulting in the loss of timing.


(1) Slip the gearcase gasket over the studs on rear of induction housing and install gearcase assembly.

(2) Install plain washers, lockwashers and nuts on studs and tighten to the torque shown in table of limits.

(3) Install magneto drives in both sides of the gearcase with the word "Top" marked on the housing facing up.  The housings are also stamped designating right or left side.  Although the drives are not right and left hand parts, it is advisable to install them on the same side from which they were removed.

(4) Install starter and fuel pump substituting covers.

(5) Install the oil pressure inlet bolt type hose elbow in the bottom of the gearcase using two new gaskets, one on each side of the elbow.  Tighten the nut to the required torque limits.

(6) Install, on the right side of the oil pump, the scavenger pump inlet bolt type hose elbow, bolts and two gaskets, one on each side of the elbow.

(7) Install, on the left side of the oil pump, the scavenger pump outlet straight type hose nipple and gasket.


Some installations may be equipped with the bolt hose type elbow same as used on the inlet.


(1) Install the breather and tachometer drive housing assembly.  Make sure the spring washer and packing are on tachometer drive shaft.

(2) Install the plain washers, lockwashers, and nuts.


(1) Install the oil sump assembly to the bottom of the crankcase.

(2) Install the plain washers, lockwashers and nuts on studs and the bolt on the front end at the link attached to crankcase.  Lockwire bolt to the bottom stud in the crankcase.

(3) Slip the hose with clamps down over the oil sump tube and install tube on the bottom of the sump.

(4) Install, loosely, lockwashers and nuts on the tube.  Slip the hose over the fitting on the oil pump.  Tighten nuts and hose clamps.


(1) Set the magnetos on the brackets and install, loosely, one plain washer and magneto attaching bolt.


(1) Install timing disc and pointer as it was installed for the valve timing.

(2) Turn the crankshaft in the direction of propeller rotation until the piston in cylinder No. 1 is coming up on the compression stroke and set the timing disc at 31 or 29-1/2 before top center depending on the method of timing.


The 31 setting is to be used when the magnetos are being timed by means of a timing light to indicate the opening of the contact points on the magneto.

(3) If a timing light is not available use .0015" feeler between the breaker points of the magnetos and set the timing disc at 29-1/2 before top center on the compression stroke of the No. 1 cylinder.

(4) Set each magneto in the fully advanced position by turning the magneto lever in a clockwise direction.

(5) Remove the magneto distributor blocks and set the internal-timing marks on the rear side of the rotor gear to line-up with the corresponding marks on the magneto front housing.

(6) Insert the two plain washers and bolts (for each magneto) in the holes where the scribed lines on the magneto drive shaft flange and the magneto coupling adjusting ring line up.

(7) If mating holes cannot be lined up or they are opposite the adjusting ring rivets, remove the magneto and magneto drive and rotate the magneto drive shaft several tooth spaces.  Reinstall drive and magneto as before.

(8) Check the magneto timing by either of the two methods outlined above.  See that breaker points on both magnetos open at the same time.

(9) When timing is formed satisfactory, install the remaining magneto to attaching plain washers and bolts, tighten and lockwire.  Tighten the adjusting ring bolts and lockwire.  Tighten magneto drive nuts.

(10) With the magnetos still in the fully advanced position, install the magneto control levers in position on the magnetos as shown in Figure 2.

(11) Adjust the magneto advance rod to the proper length and assemble to the magneto control levers.


Magnetos must be in the fully advanced position.

(12) If for any reason a magneto has been removed from the engine for replacement or retiming, it can be retimed with the undisturbed magneto in the following manner:

(a) Turn the engine in direction of rotation until the piston of No. 1 cylinder comes up on the compression stroke and stop rotating when the breaker points of the undisturbed magneto being to open, and the undisturbed magneto is in the fully advanced position.

(b) Accurately determine the opening to the break points on the undisturbed magneto by using .0015" shim or timing light as outlined above in paragraphs on final timing of the magnetos.

(c) After the timing has been determined for the undisturbed magneto install the second magneto as outlined above.

(d) Recheck the magnetos to see that their breaker points open at the same time.


(1) Rotate and lock engine mounting plate so that the crankshaft is in a vertical position.

(2) Adjust all rocker arms to have a valve tappet clearance of .010".  Proceed as outlined below:


The .010" valve tappet clearance is the cold clearance.  When the engine reaches operating temperatures the valves tappet clearance will open up to approximately .027" due to the expansion of the cylinders in a radial direction from the crankcase.

(a) Install timing disc on crankshaft, with the omitted spline in the disc hub in line with the spline blocking screw on the crankshaft.

(b) Turn crankshaft in direction of propeller rotation until the piston in No. 1 cylinder completes the compression stroke and the "TC-1" mark on the timing disc is in line with the centerline of No. 1 cylinder.  Then adjust both valve tapped clearances to .010".

(c) Turn the crankshaft in direction of propeller rotation 1-1/7 revolutions.  The mark "TC-1" on timing disc should be in line with centerline of No. 2 cylinder.  Adjust both the valve tappet clearances to .010" on the No. 2 cylinder.

(d) Continue turning crankshaft 1-1/7 revolutions at a time and adjusting valve tapped clearances to .010" until all the cylinders have had the valve tappet clearances adjusted.  Make certain that all the socket lock nuts are tight after the adjustments are completed.

(3) Install rocker box covers.

(4) Lubricate rocker arms with grease using a reliable rocker arm grease.


(1) Install and secure carburetor air heat control valve to its mounting flange on the bottom of the carburetor.


(1) Rotate and lock engine mounting plate of assembly stand so that the engine is in flight position.

(2) Install all front and rear spark plugs and gaskets.  Observe torque limits established in table of limits.

(3) Install in place the fourteen cable clips on the intake push rod tubes.

(4) Install ignition cable tube and its supporting hardware.

(5) Attach the terminal ends of the ignition wires to the spark plugs and lead the wires in the proper places through their securing clips and tube.

(6) After the cables are in place in their attaching parts, group the cables, install each cable into its magneto distributor block position and secure to distributor block with the electrode screws.

(7) Install magneto blocks on the magnetos and safety in place, being careful that the grooves on the bottom of each block are against their seating pin in the magneto housing and that the magneto blocks retaining screw is not damaged.

3.  Testing of Engine After Complete Overhaul

After complete overhaul the engine must be block, installation or flight tested.

a. The test schedule outlined herein has been worked out under the assumption that no electric "jacking-in" equipment is available.

b. A test club should be used which will allow the engine to turn approximately 2050 R.P.M. at full open throttle under standard atmospheric conditions.

c. If the test is conducted with the engine installed in an airplane in place of a regular test stand, the airplane should be faced into the wind when the test is being conducted.

d. No ring cowling should be installed on the engine for the running test.  if inter-cylinder baffles are used they probably can be installed on the engine for the test provided that it has been determined previously, by means of thermocouples installed on at least for rear spark plugs of the engine, that the particular type of inter-cylinder baffles used has no detrimental effect during the ground test on the cylinder temperature.

e. Aviation fuel of 73 octane or better should be used. The following oils should be used:

In summer - Grade 1120
In winter - Grade 1100 or 1100A

f. The following running times are recommended:

R.P.M. Minutes of Running
500 15
600 15
800 30
900 30
1000 60
1200 60
1400 60
1500 60
1600 60
1700 60
1850 30
1950 30
Full open throttle 45
Idling approx 400 R.P.M. 20



If, during the first 60 minutes of running at 1700 R.P.M. it has been determined that the oil consumption is .025 lb/HP/hr or less, 60 minutes of running is sufficient; otherwise the engine should be run for additional time at this speed until the oil consumption reaches .025 lb/HP/hr or less.  if the engine is run in an airplane, so that the specific oil consumption cannot be determined, 2.1 lb/hr of oil can be assumed as the maximum permissible oil consumption for the above condition..

Editor's Note:  Rather than extended ground running at low RPMs, modern thought is to run a new engine as hard as possible during the initial few hours of break-in so that the rings are forced to seat in.  Consult your A&P.

g.  The oil pressure should be maintained at 50 to 90 lbs/sq. in.  If the oil pump was repaired but not adjusted, and the oil pressure with warm oil is above 90 lbs/sq. in., the oil pressure should be adjusted by adding or removing washers between the spring and the pressure relief valve plug in the pressure relief valve.

h.  After the tests are completed, the baffles should be installed into place on the engine in accordance to markings put on the baffles at dismantling of the engine.

4. Preparation of Engines for Storage

a. Unless it is to be installed for operation within 48 hours the engine should be prepared for storage.

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