OMC 4.3 V6 Timing?

[CamInc62]

Need clarification on a timing question. The service manual for a OMC 4.3L V6 (1988 yr) with point ignition system states that the BTDC timing is set @ 1 degree for regular fuel and @ 6 degrees for premium. This is a long way apart. I have twins and can somewhat regulate what type of fuel I run locally, but if I am travelling I am subject to what the marina's have in the area.

I am from Canada and our octane ratings range from approx. 87 to 94 with percentages of ethanol, which I personally don't like because of the heat factor and dryness. It also takes the storage factor drastically out of fuel, but we are subject to that here.

Does anyone have a "happy" medium to as where these engines run decent over the range of octane ratings? I would think 3 or 4 degrees but am guessing? I would hate to have to think I need to adjust timing for a couple of octane ratings with fuel.

Craig

 

[Lou C]

Re: OMC 4.3 V6 Timing?

I get 93 octane at the marina and have always set mine at 6*, with no problems.

 

[Bondo]

Re: OMC 4.3 V6 Timing?

Need clarification on a timing question. The service manual for a OMC 4.3L V6 (1988 yr) with point ignition system states that the BTDC timing is set @ 1 degree for regular fuel and @ 6 degrees for premium. This is a long way apart. I have twins and can somewhat regulate what type of fuel I run locally, but if I am travelling I am subject to what the marina's have in the area.

I am from Canada and our octane ratings range from approx. 87 to 94 with percentages of ethanol, which I personally don't like because of the heat factor and dryness. It also takes the storage factor drastically out of fuel, but we are subject to that here.

Does anyone have a "happy" medium to as where these engines run decent over the range of octane ratings? I would think 3 or 4 degrees but am guessing? I would hate to have to think I need to adjust timing for a couple of octane ratings with fuel.

Craig

Ayuh,.... The Problem is, Detonation usually can't be heard in a boat,...

If ya set the timin' to 1?Btc, it'll run on any fuel, but will/ could be slightly down on power,...

If ya set it to 6?Btc, 'n ya run low grade fuel, it'll burn a hole in a piston, before ya hear the Detonation,...

Custom settin' the timin' involves Readin' the spark plugs, so ya Don't set up Detonation,...

 

[jbetzelb]

Re: OMC 4.3 V6 Timing?

I have my 1989 set at 6 degrees and I almost always run non-ethanol 91 octane. Only exception is when I buy on the lake and it is usually non-ethanol 92 octane. I have run that way for 15 years. Again, as noted in posts above, I know I am running good fuel whether I am on the local mud hole or the couple big lakes I travel to. I suspect you could be safe with at least 3 degrees if your fuel varies alot.