Optispark II installation oreientation question
Thread Starter
East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
Optispark II installation oreientation question
I am sure this quesiton has been asked before, but my DSL is down and I am on dial-up so it takes me too long to search. 
I just recently installed a new cam, timing set, and water pump. I have a book "How to Rebuild LT1's/LT4's." In this book the author makes specific mention of the fact that the dots do not need to line up (6 o' clock cam dot, 12 o' clock crank dot) on the crank and cam sprockets to install the distributor. Instead he recommends that the cam sprocket dot and the crank sprocket dot both be at 12 o' clock. The piston will be at TDC at either orientation. Can someone explain why it is necessary to install the distributor in this manner?
I just recently installed a new cam, timing set, and water pump. I have a book "How to Rebuild LT1's/LT4's." In this book the author makes specific mention of the fact that the dots do not need to line up (6 o' clock cam dot, 12 o' clock crank dot) on the crank and cam sprockets to install the distributor. Instead he recommends that the cam sprocket dot and the crank sprocket dot both be at 12 o' clock. The piston will be at TDC at either orientation. Can someone explain why it is necessary to install the distributor in this manner?
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
As long as the timing chain is installed properly with the dot on both the crank and cam gear at the 12 o'clock position the cam pin will be at the 9 o'clock position. Cylinder 1 will be at TDC on the compression stroke.
The optispark is driven by a pin on the camshaft. So if the timing chain is installed properly you supposedly can't install the optispark in the wrong position but some people have forced the optispark on and the drive pin wasn't installed in the proper position.
Click on the link below.
http://www.shbox.com/1/cam_timing_ani.gif
The optispark is driven by a pin on the camshaft. So if the timing chain is installed properly you supposedly can't install the optispark in the wrong position but some people have forced the optispark on and the drive pin wasn't installed in the proper position.
Click on the link below.
http://www.shbox.com/1/cam_timing_ani.gif
Thread Starter
East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
As long as the timing chain is installed properly with the dot on both the crank and cam gear at the 12 o'clock position the cam pin will be at the 9 o'clock position. Cylinder 1 will be at TDC on the compression stroke.
The optispark is driven by a pin on the camshaft. So if the timing chain is installed properly you supposedly can't install the optispark in the wrong position but some people have forced the optispark on and the drive pin wasn't installed in the proper position.
Click on the link below.
http://www.shbox.com/1/cam_timing_ani.gif
The optispark is driven by a pin on the camshaft. So if the timing chain is installed properly you supposedly can't install the optispark in the wrong position but some people have forced the optispark on and the drive pin wasn't installed in the proper position.
Click on the link below.
http://www.shbox.com/1/cam_timing_ani.gif
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
I agree, but there are two possiblities here. You can have the cam dowel pin at 9 o' clock this would mean that #1 would be at TDC on the compression stroke. Or, you could have the dowel pin at 3 o' clock and #1 would be at TDC on the exhaust stroke. Either way the opti will bolt up just fine. I was just wondering why the author specifically mentions that you should install the opti with the dowel pin at 9 o' clock instead of at 3 o' clock.
The relationship between the dowel pin and the opti shaft that turns the rotor inside the cap will automatically orient the rotor so that it is pointing at the #1 spark plug wire, hence fire, gas, compression, start.
Think about it some.
