Cam shaft service

Question 1

Before disassembly what is an important measurement?

Answer 1

Backlash, this cannot be measured after disassembly

Question 2

If there is an idler gear how many locations is backlash measure and where?

Answer 2

2. crank and idler, cam and idler.

Question 3

Chain shaft slack should not exceed?

Answer 3

12.7mm or 1/2”

Question 4

a worn chain and sprocket will?

Answer 4

result in retarded timing

Question 5

How are straight bodied lifters removed?

Answer 5

through the top and before cam removal

Question 6

how are mushroom type lifters removed?

Answer 6

through the bottom and after cam shaft removal.

Question 7

Keeping followers together is important because ?

Answer 7

they have specific wear patters and if they are not put back to right cam lobes, premature failure can occur.

Question 8

Roller lifters/followers after cleaning should have?

Answer 8

pin and rollers lubricated with clean oil to prevent seizing.

Question 9

Fuel injector lobes are more prone to?

Answer 9

surface fatigue, due to the high stress loads.

Question 10

check cam shafts for discoloration, why?

Answer 10

discoloration due to lack of lubrication (overheating), cams are replaced not re used.

Question 11

Straightness (runout) front and rear journals should be checked for?

Answer 11

Check that cam shaft journals (front and rear) are not out of round before checking other journals.. false reading.

Question 12

Other indicators of bent cam are?

Answer 12

-binding or tight spot when rotating in cylinder block.
-un even cam shaft wear.

Question 13

Valve lobe measurements?

Answer 13

Base circle A
Lobe height B,
minus B-A.
make sure to get highest point of nose and only base circle.

Question 14

Worn valve lobes cause what effects?

Answer 14

affects valve timing, resulting in loss of power and causing rough-running engine.

Question 15

Measuring fuel injector lobes?

Answer 15

usually on the opening ramp side, highest loads on this side.

Question 16

Solid type (flat faced) lifter wear?

Answer 16

because of side thrust and sliding wear can happen body of the follower, also on face and cam lobe.

Question 17

is concave wear acceptable on follower face?

Answer 17

no, discard.

Question 18

Extreme cupping is a result of?

Answer 18

lobe failure, lack of lube, poor maintenance, or houred out.

Question 19

Roller type follower wear?

Answer 19

less side thrust, on roller face and cam lobes but also between roller and supporting pin.

Question 20

When removing a gear are key ways important?

Answer 20

Yes, because they can be used for timing.

Question 21

Excessive backlash in gear will result in?

Answer 21

retarded timing.

Question 22

Worn camshaft bearings will result in?

Answer 22

• not support cam sufficiently.
  -increase bearing to journal oil clearance (low oil pressure.
  -could reduce valve mechanism oil flow

Question 23

insufficient end play is the result of?

Answer 23

-camshaft thrust plate being installed backwards.
- misalignment
-foreign material behind thrust plate.

Question 24

Flat faced and roller type lubrication?

Answer 24

-flat-faced extreme pressure grease.
-roller type clean engine oil