Alfa Romeo 33 owners manual page 42

text version of content this owner's manual page from owners manual to the vehicle Alfa Romeo 33, year of production 1983 - 1995:

ENGINE MAINMECHAN1CA.L UNIT grinding, in order to ensure exact Valve Engine guide/seat perpendicularity aswell 12(N) 1350 1500 as proper valve working position. Valve seat 38.875+ 38.9 VALVE SEATS outer (1.5305 + 1.5315) diameter 33.375+ 33.4 1. Check valve seats for any scores, mm (in) (1.3140~1.3150) cracks or burrs and make sure they are properly fitted in their respective 38.8 + 38.825 Diameter recess on the cylinder head. of valve II .5276 + 1.5285) 2. If necessary, mount the head on Seat recess 33.3 + 33.325 tool A.2.0226 and regrind the valve mm (in) (1.3110+1.3120) seats using the proper tool. This operation may be performed as i. = intake valve e. = exhaustvalve long as there is sufficient grinding allowance that will permit eliminat- 0 ing the existing flaws while keeping 1 Valve seat3 Profileafter max. 3. Oven preheat the head at 140°C the specified profile; contrarywise, 2 Original profile regrrdrng (284°F). valve seats will have to be replaced. 4. Fit new valve seats using the For relevant procedure see para- graph: “Valve Seat Replacement”. proper tool. (4) Having completed all machining, lap valve seats with proper tool. Checking valve tightness (1) Regrind valve contact face till all evidence of wear has been removed When replacing guides, after regrind- and following taper is obtained : ing and lapping of seats, it is advis- p = 90” t 90” 30’ able to test valve tightness- with valves and sparkplugs duly mounted- of dimension “a” on the “0” reference diameter. according to the following pro- cedure: 0 Reference diameter: 1. Mount the head on tool A.2.0226 andA.2.0195 previously Intake = 37.3 mm (1.4685 in) secured in a vice. Exhaust = 31.9 mm (1.2559 in) 2. Fill the combustion chamber “a” dimension at max. regrinding limit: cavity with gasoline. 2.9 mm (0.1142 in) 3. Let some low-pressure air into the intake ducts and check for presence of air bubbles in the gaso- (2) Machine the valve seat upper face still the6 reference diameter line. position obtained through the pre- vious operation is reached, attaining the specifiedCL taper. Taper of valve seat upper face a=120° (3) Machine the seat inner face till dimension “b” of the valve contact For seat lapping use the proper face is restored, attaining the speci- lapping compound (SIPAL 4. Follow the same procedure and fied y taper. check tightness of the exhaust valves AREXONS Carbosilicium for valves- by letting low pressure air into the Height of inner face: Std. no. 4100-31502). exhaust valve ducts. Intake: b = 1.07+ 1.37 mm 5. Should there be some leaks, (0.0421 + 0.0539 in) ascertain that valves are properly Exhaust: b = 1.26+ 1.56 mm Valve seat replacement fitted in their seats and then repeat (0.0496 + 0.0614in) 1. Remove worn valve seatsusing above tightness tests; if the results the proper tool. are negative, valve seats will need 2. With a set of new valve seats Taper of valve seat lower face: relappin,g as indicated in paragraph: Intake: y = 50” verify that dimensions shown in the Checks and Inspections- Cylinder Exhaust: y = 30” following table are complied with: Heads and Valves- ‘Valve Seats. 01-19 May 1983

owners manual Alfa Romeo 33

owners manual Alfa Romeo 33 - year of production: 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995 - Alfa Romeo 33 owners manual EN