Quote Originally Posted by Fast355 View Post
I am attaching the advance curve in the 5.7 Marine module. The distributor times at 8*BTDC and all values in the table are without the 8* base added to them. So basically add 8* across the board. As for vacuum advance, a good high performance advance curve mimics the old delco vacuum advance on the L79 327, LT1 350 and L82 350. 10* @ 10 in/hg with 0* until 5 in/hg. Should work out a bit better. At WOT you would get
23* @ 1,000 rpm,
24.5 @ 1,500,
26.5 @ 2,000,
28.5 @ 2,500
30* by 2,800 rpm.
At idle the timing would be 30.5 @ 750 rpm.
2,000 rpm cruise 36.5
3,000 rpm cruise would give 40* advance.

That should get you fairly close, then make slow changes from there. The advance curve on my L31 Express van was very similar to what I said above. With the CNP 5.3 coils I ran up to 48-50* timing at cruise though for best fuel economy and throttle response.
Thanks for your response fast355.

Oh wow, that’s wild! I would’ve never guess that high for a vortec.

I’ll give that a go and report back with my findings. Since my distributor has no mechanical or vacuum advance (all electronic) I must’ve really been missing the mark. Hopefully this will wake it up.

Quick question, why do so many engine ‘gurus’ claim the vortec engines like really low total timing? Say 30* or so... or am I again missing the mark?

I’ll post a picture of my timing tables and graphs before and after when I get to my laptop.

Thanks again guys!

Btw, I like to support forums that help me. Is there a paid membership to help the people who manage the board?