Well I was putting my LT1 back together and did the timing chain as I always do with the dots on the crank sprocket and timing gear sprocket lined up. This is with #1 piston at TDC (top dead center). I was using the FSM and the HP books How to rebuild LT1/4 engines.
Well Look at the pictures and see what the problem is. This book , the HP is a convenient book, and so i thought a good one. Now I am wondering.
I use the FSM 99% of the time. For this build I was using the ARP bolt torques recommendations etc and JE pistons ring layout, so nothing critical is wrong. But when I saw this as I was putting the timing cover on, I noticed the timing marks (according the HP Books, which I didnt use for the timing marks)didnt line up with the FSM. SO, this is a lesson I have found and am putting out to everyone else. I will also send this to HP.

 

I'm not sure what your concern may be. When the cam is installed with the cam sprocket dot nearest to the dot on the crank sprocket, both the #1 and #6 pistons are at the top of their respective bores but only #6 is at true TDC. When the cam sprocket dot is at the top of its rotation, #1 is at TDC and #6 is on the reverse side of the firing cycle. In order to see the difference put the lifters in, bolt on the odd side head, install the pushrods and try to adjust the valves on #1 in both positions of rotation.

 

Your mechanical timing will be off, and the engine wont run right. That is the concern.

 

The two references do not serve the same purpose. The FSM diagram is showing you how to install the timing chain (dot to dot, #6 at TDC, cam dowel at 3:00 o'clock). The HP book is showing you how to align the dowel pin to install the Opti (although I'm not sure why you need the pin at 9:00 o'clock - #1 at TDC - to install the Opti???)

 

Strange. Well, I guess its not important. They did this engine into a carbe'd distributor type too. So maybe they were doing two things at once and just didnt explain.

 

Because whoever wrote it thought it was relative to a TSBC.

 

Tsbc?

 

I don't see what the concern is. Both pictures say [accomplish] the same thing and both are correct.

 

As long as the opti is following the cam. The camremember spins at a different speed, As stated both #6 and # 1 will be at tdc when the dots are aligned, the cam has only one way the valves are opened and the dist is referenced to the cam so onlythe one with the correct valve timing will be the one firing wether it be #6 or # 1. If the dowel is on the left the opti will fire # 6 , on the right #1.

 

Traditional Small Block Chevy

 

Yes, this is completely a non-issue with the Opti. All that matters is the cam pin engages the correct slot in the Opti hub.

WD