optispark.. the most dredded component of the LT LS family

[94formulaLT1]

okay i was wondering something about the opti...when your engine's #1 pistion is TDC, where are the key ways on the optispark shaft for a 94 lt1? is the key way facing the bottom, top...where.. im hoping this is a way to check TDC

[Rob B (shoebox)]

Looking at the front of the engine, the cam dowel should be at the 9 o'clock position to be at #1 TDC. This should put the keyway for the unvented opti at 12 o'clock.

[Injuneer]

optispark.. the most dredded component of the LT LS family

And just to clarify, there is no Optispark on an "LS".

[94formulaLT1]

lol i realize that now..ha i wasnt thinkin..okay so when the #1 cylinder is at TDC...the dowl pin should be at the 9 o'clock position? are you sure it is not suppose to be at the 3 o'clock position?

And just to clarify, there is no Optispark on an "LS".

[Rob B (shoebox)]

lol i realize that now..ha i wasnt thinkin..okay so when the #1 cylinder is at TDC...the dowl pin should be at the 9 o'clock position? ...

On an LT1, I can guarantee it.

[94formulaLT1]

then how come my book shows the hole for the cam dowl pin in at the 3 oclock position when the engine is at #1 TDC? i turned my engine over when i first started until the dots were at 12(crank) and 6(cam) and the #1 cylinder cam to TDC, not 6..remembering i have a 94 lt1..

[Rob B (shoebox)]

#1 and #6 pistons are physically at the top at the same time. It's the cam lobe position that determines which one is on the intake or exhaust stroke.

[94formulaLT1]

all i basically want to know is is it possible i have harmed my engine.. when i had everything on and i was setting zero lash i would turn the engine over by hand...and nothing would ting or clank so im sure i didnt make piston to valve contact..

i dont understand...BEFORE i took my timing chain and everything off, i lined up the dots..12 and 6 and #1 pistion cam to TDC..not six, so that is how i put everything back together..that is what i dont understand...is it possible that my engine is different or something...i just dont know, im out of idears..

#1 and #6 pistons are physically at the top at the same time. It's the cam lobe position that determines which one is on the intake or exhaust stroke.

[fastTa]

all i basically want to know is is it possible i have harmed my engine.. when i had everything on and i was setting zero lash i would turn the engine over by hand...and nothing would ting or clank so im sure i didnt make piston to valve contact..

i dont understand...BEFORE i took my timing chain and everything off, i lined up the dots..12 and 6 and #1 pistion cam to TDC..not six, so that is how i put everything back together..that is what i dont understand...is it possible that my engine is different or something...i just dont know, im out of idears..

You mentioned to me that you had your camshaft out. What method did you use to properly degree the cam and what type of piston stop did you use. I'm assuming you used a spark plug hole stop since you didn't mention having the heads off.

TDC is not only when the piston is at the top of it's stroke, it's when the piston is at the top of the compression stroke. That is critical.

If you were dividing the sum of the two degree wheel angles by 2 to find true IC (intake centerline) based upon the crankshaft being in a postion that allowed the cam/crank sprockets timing dots to line up, then you need to have #6 at TDC not #1.

[Rob B (shoebox)]

all i basically want to know is is it possible i have harmed my engine.. when i had everything on and i was setting zero lash i would turn the engine over by hand...and nothing would ting or clank so im sure i didnt make piston to valve contact..

i dont understand...BEFORE i took my timing chain and everything off, i lined up the dots..12 and 6 and #1 pistion cam to TDC..not six, so that is how i put everything back together..that is what i dont understand...is it possible that my engine is different or something...i just dont know, im out of idears..

12 and 6 is #6 TDC. That's all there is to it. 12 and 12 is #1 TDC. Your engine is not different.

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