When changing timing chains shop manual says to position camshaft sprocket marks at 12"00 and crankshaft sprocket marks at 12"00 then rotate crankshaft 360 or 1 turn. This places the camshaft sprocket mark at 6"00 and the crankshaft sprocket mark again is back to 12"00.Thus the 2 marks are now oposite each other at 6'00 and 12"00,which is where they should be at the end of the timing chain installation.Question is do you stab the distributor pointing the rotor to #1 on the cap while the marks are at 12"00 /12"00 or at 6"00/12"00.I would think stabbing it at 12/12 because that represents #1 compression stroke,but ya never know so hip me please.
timing on 1998 Chevrolet Express 3500
by ffasteddie in Glendale, AZ on July 21, 2010
1 answer 1 comment
ANSWER by mastertech6371 , July 21, 2010
traditionally, 350 timing chains are installed with 12 on the crank and 6 on the cam for compression stroke. follow the procedure as outlined. if you want to be sure, pull a valve cover and make sure of the stroke by the position of the valves. Roy
COMMENT by ffasteddie , July 21, 2010
With all due respect the A/C pump must be pulled to gain access to the L/H valve cover dont mean to bitch but its 108 in the shade and i dont have any.I can determain what stroke #1 is in by using a compression gauge or my finger while my girl turns it over.My ignorance lies in not knowing why the Chilton even bothers to mention to rotate the crankshaft 360 or 1 turn before starting this R&R. If its NOT relavent what are thos bozos thinking.Again the distributors out,both sprockets out,engine is at #1 compression stroke...install the sprockets at 12/12 rotate it 360 and stab the dist at #1 cyl.OR install sprockets at 6/12 stab the dist. at #1 cyl. and forget the rotation ?