gm_71chevelle
Dec 5th, 05, 03:13 PM
Hey guys i have recently started installing a new cam (Comp Cams Dual Energy 275 DEH) in my 350. Now i am ready to install the timing gears. But heres my question, before i started all the work i put the motor to top dead center which is the #1 piston on compression stroke. But when installing the timing gears you are supposed to line up the dots (cam dot at 6:00-crank dot at 12:00). But when doing this that is supposed to put the #6 piston to fire. Then you rotate the crank 360 degrees to have both dots in the 12:00 position to get it to #1 fire again. Now im a little confused, with the motor already at TDC for #1 will i have to rotate the crank gear to line the dots up and thats why #6 would be at firing position when they line up? Any responses would be appreciated thanks.
camcojb
Dec 5th, 05, 03:20 PM
You could have the motor at TDC#1 and put both dots straight up. The only danger of this is it's easy to be a tooth off this way. I really recommend lining the dots up, or do it your way and spin the engine 360 degrees to make sure they're properly aligned. Then spin another 360 degrees to get back to #1.
Jody
JimM
Dec 5th, 05, 06:15 PM
note: until the cam gears are on, there is NO tdc #1 firing. It doesn't exist yet, and won't until the cam is phased. The cam, not the crank, determines where the firing stroke is.
gm_71chevelle
Dec 5th, 05, 06:26 PM
so im still a little confused, when the #1 was, and still is at TDC if i put the crank gear on with the dot straight up (12:00) i can just put the cam gear on with the dot at 6:00 and not have to worry about #6 being at TDC? Because that is supposed to be #6 fire but #1 is at TDC, kinda hard to explain
camcojb
Dec 5th, 05, 07:30 PM
so im still a little confused, when the #1 was, and still is at TDC if i put the crank gear on with the dot straight up (12:00) i can just put the cam gear on with the dot at 6:00 and not have to worry about #6 being at TDC? Because that is supposed to be #6 fire but #1 is at TDC, kinda hard to explain
Line up the dots when installing the timing chain/gears. Cam gear at 6:00 and crank gear at 12:00. Then spin the engine 360 degrees and you will be at #1 TDC with both marks facing straight up.
Jody
gm_71chevelle
Dec 5th, 05, 09:03 PM
ok i understand now thanks for the replies
dnult
Dec 6th, 05, 07:27 PM
...that is supposed to be #6 fire but #1 is at TDC... Saying that a cylinder is on fire and TDC are the same thing. TDC means both valves are closed, with the piston at the top of the stroke ready for a spark to set it off. If #1 is on TDC, then #6 is on the peak of the exhaust stroke (exhaust valve closing and intake valve opening).