After disassembling the block head, rinse all parts in gasoline, wipe and dry.
Clean the combustion chambers of carbon deposits.
Inspect the block head. If there are cracks on the lintels between the valve seats or on the walls of the combustion chambers, traces of burnout, replace the block head.
Check with a metal ruler and probes whether the flatness of the surface of the head adjacent to the block is not violated.
To do this, place the ruler with an edge on the surface of the head, in the middle along, and then across and measure the gap between the plane of the head and the ruler with probes.
If the gap exceeds 0.1 mm, replace the head.
Inspect the valves. If cracks, warping of the valve head, burnout, deformation of the valve stem are found on the working chamfer of the valve, replace the valve.
Minor risks and scratches on the working chamfer of the valve can be removed by lapping.
We look at the order of lapping the valves in the article - "Disassembly and assembly of the cylinder head".
Check the condition of the valve springs. Replace the springs that are twisted, broken or cracked.
Check the condition of the valve seats. There should be no signs of wear, shells, corrosion, etc. on the working chamfers of the saddles.
Minor damages (minor risks, scratches, etc.) can be removed by lapping the valves. More significant defects are eliminated by grinding.
When grinding, maintain the dimensions of the seat indicated in the figure.
After grinding, check the runout of the seat chamfer relative to the hole in the valve guide sleeve, the maximum allowable runout is 0.05 mm.
After grinding the seats, grind the valves.
Then thoroughly clean and blow the block head with compressed air so that there are no abrasive particles left in the channels closed by the valves and in the combustion chambers.
Check the gap between the guide bushings and the valves.
The gap is calculated as the difference between the diameter of the hole in the sleeve and the diameter of the valve stem.
The maximum allowable gap is 0.25 mm.
If the clearance exceeds the specified one, the valve and the guide sleeve must be replaced.
The old sleeve is pressed out using a mandrel from the side of the combustion chamber.
Before installation, the new bushings need to be cooled in carbon dioxide ("dry ice"), and the block head heated to 160-175 ° C.
Then insert the sleeve into the block head so that it protrudes from the side of the valve springs above the block head by 20 mm.
The sleeve should be inserted into the head freely or with little effort. After installation, expand the hole in the sleeve to a diameter of 9.0+0.022 mm.
Then sand the valve seat, centering the tool along the hole in the sleeve.
8. Check the block head for the absence of cracks as follows. Bring a compressed air hose to one of the openings of the cooling jacket.
Plug all holes in the block head with wooden plugs. Lower the head into a bath of water and apply compressed air at a pressure of 1.5 atm.
In places where cracks form, air bubbles will come out.
9. Clean the holes in the rocker arm axis, in the rocker arms and in the adjusting screws with wire and compressed air.
Check the fit density of the bushings in the rocker arms.
If the bushing does not sit tightly, it needs to be replaced, since during engine operation it can turn around and block the oil supply hole to the pusher rod.
The dimensions and fitments of the cylinder head parts are indicated in the tables.
Nominal dimensions of the cylinder head
|
Name the details |
Nominal diameter, mm |
Name mated details |
Nominal diameter, mm |
|
Guide valve sleeve |
17,0 +0,066 17,0 +0,047 |
Block head cylinders |
17,0 +0,025 17,0 -0,010 |
|
Intake valve |
9,0 -0,050 9,0 -0,075 |
Guide bushing |
9,0 +0,022 |
|
Graduation valve |
9,0 -0,075 9,0 -0,090 |
Guide bushing |
9,0 +0,022 |
|
Intake seat valves |
49,0 +0,125 49,0 +0,100 |
Block head |
49,0 +0,017 49,0 +0,010 |
|
Graduation Saddle valves |
42,0 +0,125 42,0 +0,100 |
Block head |
42,0 +0,017 42,0 +0,010 |
|
Rocker arm axis valves |
22,0 -0,007 22,0 -0,021 |
Axle stand rocker arm |
22,0 +0,030 22,0 +0,008 |
|
Rocker arm axis valves |
22,0 -0,007 22,0 -0,021 |
Rocker arm sleeve valves |
22,0 +0,028 22,0 +0,007 |
|
Rocker arm sleeve |
23,4 +0,07 23,4 +0,04 |
Rocker arm valves |
23,25 +0,045 |
|
Plug |
17,0 +0,115 17,0 +0,080 |
Rocker arm axis valves |
17,0 ±0,035 |
Fitting of mating parts of the cylinder head
|
Name the details |
Gap, mm |
Tension, mm |
||
|
min |
max |
min |
max |
|
|
Guide valve sleeve |
— |
— |
0,022 |
0,076 |
|
Intake valve |
0,05 |
0,97 |
— |
— |
|
Graduation valve |
0,075 |
0,117 |
— |
— |
|
Intake seat valves |
— |
— |
0,083 |
0,135 |
|
Graduation Saddle valves |
— |
— |
0,083 |
0,135 |
|
Rocker arm axis valves |
0,015 |
0,051 |
— |
— |
|
Rocker arm axis valves |
0,014 |
0,049 |
— |
— |
|
Rocker arm sleeve |
— |
— |
0,145 |
0,220 |
|
Plug |
— |
— |
0,145 |
0,150 |