1.... You are correct: It's not off a tooth if the timing is spot on.
2.... I suspect you have either a sticking spark advance (common problem due to the harsh marine environment) or a bad wire/ plug.
3... Note that marine engines live a far more severe life than car/ truck engines, for boats are 'going uphill' all the tme (and it's a steep hill!)
1.... I'd have to agree with Jeff. One tooth off on the distributor/cam gear would not cause this. The mechanic is not thinking this through completely!
BASE Advance is a result of the distributor housing position when locked down........, and the progressive and Total Advance is a result of distributor function after that.
You could actually install the distributor in as many index fashions as there are teeth on the distributor/cam gear.
As long as the plug wires were indexed into the cap correctly, the spark plugs and engine won't know the difference.
2... Jeff, I read where these are new HEI ignition systems. 200toncapt (the OP) says;
Delco HEI
If I'm correct, the Delco HEI is available in mechanical advance and/or EST.
200toncapt, which did you purchase? EST or Mechanical advance HEI?
Chris and I were just talking about EST systems and knock sensors picking up on other than a Detonation knock. He went on to tell me that he's seen a knock sensor pick up on a bad gimbal bearing, and then send that signal to the controller, which in turn cut back on TA.
If I understand this correctly, it may be possible that one could also pick up on a bad universal joint system, and perhaps something else (key word "may"). This would only be if your HEI was EST w/ a knock sensor. Not mechanical advance.
But if so...... looking at TA numbers while under NO LOAD, may not reveal what's actually occuring while under load... such as what you describe with the now lower RPM on your Stbd Engine! (i.e., Stbd Engine system cutting back on TA resulting in lower RPM)
Just a thought!
3... and the hill never ends!
200toncapt, just as with the P of E (process of elimination) when trouble-shooting, we check/change out one item, and one item only, and then test for results. It may be possible that you over-looked something in the process of making all of these changes at one time, rather than one at a time.
With 20 years experience, I certainly understand that we often deviate from this. But once in while it can come back and kick us in the behind!
As for timing marks as per Chris, it's a shame that all Marine Engines do not come from the factory with the harmonic balancers engraved and marked off permanently so we can check TA dynamically. Many of the high performance engines do.
I'm not a tremendous fan of using the digitally advancing timing lights. I prefer to see the advance in Real Degrees/Real Time.... but that's just me I suppose.
.
