[alfa] Spica timing

[Jon Pike <jhpike@xxxxxxx>]

No,  no!  You are exactly as you should be.

Since you rotated 80deg (70?) backwards from the #1 intake stroke,  
you're almost back at the #4 power stroke..  each cylinder on the same 
"side" of the crank is out of phase with the other,  i.e. both #1 and #4 
are "up" at  the same time, though one is intaking while the other is 
igniting and powering.

If you don't believe me, here's a quote from Wes's Spica book: "If the 
engine is at the correct position the rotor in the distributor will be 
approaching the #4 plug wire.  Remember the the configuration of the 
pulleys will loop the same for firing the #1 cylinder and the #4 
cylinder, so it its important to make sure you have positioned #4 to fire."

Not very intuitive,  till you get a mental picture of what fires when.  
I had to go out and crank the motor over while watching the cams to make 
sure I didn't write this funny..  Final test,  if you crank forward from 
the I mark,  you should come up on #1 TDC during overlap, and another 
full rev and it should be on #1 TDC with both valves closed (power 
stroke) lobes out, and the rotor pointing at #1.  Another almost full 
crank and you should see the Spica mark when you pass the I again on the 
way to #1 TDC overlap.

So, you're spot on, man!  Now don't you feel a whole lot better?

Jon  (who proudly pulled and cleaned a transmission and bell housing today)
77 Spider
Irvine, CA


> Whilst the Spica unit has been removed, the distributor has not. To
> replace the Spica belt, one aligns the marks on the Spica 'pulley' and
> the upper mark on the unit. Then using the prescribed method - whereas
> at TDC the #1 inlet lobe is just about to open the inlet valve and the
> exhaust valve is just closing, one rotates the crankshaft
> counterclockwise 80 degrees to align 'I' with the pointer and installs
> the belt.
>
> Should you buy the above, I would now have it pointing 180 degrees
> opposite (from the original #1 on the distributor) to #4. Will admit,
> the cams were removed (and replaced).
>
> Should I now make #4, #1?
>
> Breathlessly awaiting your answer.
>
> Biba
> Irwindale, CA USA
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