3.8 OMC Ignition Timing

[Rosbullterrier]

Just finishing the V6 engine rebuild but now find the water pump double groove pulley is so big it swamps vision of the timing scale on the crank pulley.
I can just about see it from the side - but the other unfinished engine has an additional timing scale bolted (to the timing chain cover) on the right of the original scale (which is spot welded to the timing cover)
Which should I use? They both show 0 to 12 degrees before and after TDC - except the bolted on one is about an inch further around the crank pulley!

 

[Howard Sterndrive]

Re: 3.8 OMC Ignition Timing

there are different crank dampeners that go with the different timing covers. I know that from using a 229 automotive crate engine in my boat.
The TDC line in the dampener is in a different place than on marine.

I used the auto dampener and a chrome timing cover, so I abandoned the pointer. I found TDC#1 with a timing tool, drew a line to the side of the engine - down near the oil pan, then measured my dampener circumference and divided it into degrees. Used white-out to paint TDC and 8 deg advance marks on the dampener.

A timing tool in the spark plug hole should help you to figure out where TDC 0 degrees is.

 

[zbnutcase]

Re: 3.8 OMC Ignition Timing

By 'timing tool', I believe he means a piston stop that screws into the spark plug hole. And turn engine by hand only, not with the starter!!

 

[Howard Sterndrive]

Re: 3.8 OMC Ignition Timing

thanks - yeah - I guess it's called a TDC tool actually? - mine is a brass pipe fitting and an old sbc pushrod that were laying around - I just screw the fitting in gently, and the pushrod slides through it

 

[Rosbullterrier]

Re: 3.8 OMC Ignition Timing

I am very grateful. Never having seen such an engine in a car I should not have thought of the different application. Is 8 degrees BTDC for this marine engine? I can't give it a final road test as you would a car!

 

[WSUDERMAN]

Re: 3.8 OMC Ignition Timing

I don't know the btdc for that engine but on our old 78 that had a 305 had really good results using the vacuum gauge method for timing. There are lots of how to's on the web for this. ie http://automotivemileposts.com/garage/v2n8.html

Wes

 

[Howard Sterndrive]

Re: 3.8 OMC Ignition Timing

OMC spec'd 8 deg BTDC, Mercruiser said 10 degrees for the same engine so take your pick