OK I get it, you don't want to spend $100 on a critical tool that insures your boat performs correctly and does not blow up. Try this. If at 2500/3000 RPM you are getting 12 deg advance measure the distance on the harmonic balancer from 0 to 12 deg. Double that measurement and make a mark on the balancer, now you have a 24 deg mark. Spin the motor to 3000/3500 RPM and see where your 24 deg mark is. Cheap, easy not real accurate but not terrible either. Good luck

If you need just set the total to the 24 mark @ 3500 RPM by adjusting the distributor at 3500 RPM. Check the base at idle and I bet it reads about 10-12 deg.
Am I missing something.
Disclaimer: I run a T-Bolt ignition and carb set-up. 34 deg all in base about 10.

BTW: Many sources say to apply the + wire for the timing bypass'wire' set up when engine is running only/ May damage module they say.
Where is one of many sources that mention this:
https://forums.iboats.com/forum/engi...ming-procedure

Again. I just set total, therefore I don't have to use such methods

I'm wrong and should have remembered, module provides 22-23* advance - but comes in ultra fast from 600rpm or so:
Curve and etc is in here:
http://www.boatfix.com/merc/Techbk/95/95HGB4.PDF

EST? Small cap HEI with Delco Voyager module? Module is only good for about 12° advance. It is really a pass car module that has some centrif advance built in to limp mode. You could have another chip that has no advance built into limp mode.

Ok, in a 4cyl you get about 24 degrees. Doable.

first and foremost have to say about the Merc --- this is not a Volvo set up so do not use the Volvo info. the info about this is --- for one Merc uses a shift interupt switch VOLVO DOES NOT. With Merc for this EST --- you have to bypass the shift interupt when checking timing and or setting timing. With that said -- you unplug the shift interupt and plug leads together using a connector wire with bullet connectors. Have no idea if this has been mentioned or not plus nor do I want to read all thru the replies posted. Sorry about that one

Timing lite properly connected -- fully warmed engine -- idle speed 600 rpms install jumper wire between the 2 white leads on the distributor. Next is to by pass the shift interuptor switch. verify that timing does advance to - initial timing 1 BTDC advancing to 12 BTDC + or - 2 degrees next is at 2400 - 2800 rpms --- max total advance should be 23 BTDC + or - 2 degrees.

There you go hope this helps whomever fully the correct OEM info and procedures here . Good luck.

. And again the cam gear is very bad about wollowing out the keyway slot JUST some added info and FYI as well.

Kent Moore sells an EST module tester for anyone interested.

forgot to add the timing chain gets worn out here as well - 400 to 500 hours these engines need alot of attention internally. They also corrode from the outside in very easily from any salt air content