timing advance

[milkman250]

Hey guys I'm new here but been reading some of your answers and its been helping me out. I have an 88 4.3 omc and can't get the timing to advance more than 18 degrees. The springs seem to be working rite when moved by hand, any sug
gestions thanks

 

[gbeltran]

Re: timing advance

It's not supposed to advance any more than that. 6 initial, 18 total. That's the factory spec, for 89 or better octane fuel.

 

[milkman250]

Re: timing advance

Oh I thought 28 degrees was total, I'm running 93 octane and at 8 btdc, I can advance by hand and pick up 400 more rpms

 

[gbeltran]

Re: timing advance

I wouldn't advise it. Why do you need the RPM, are you not running in the specified wide open RPM range? They limited that advance curve for a reason, driving your boat is like running a wheeled vehicle up hill in high gear, there is a tremendous amount of load on the engine compared to a car, and too much timing can lead to detonation, holes in piston, broken rings.....

 

[SeanMcl]

Re: timing advance

Oh I thought 28 degrees was total, I'm running 93 octane and at 8 btdc, I can advance by hand and pick up 400 more rpms

I am guessing the "8 btdc" is a typo and you meant "18 btdc". In any case, if you have only 18 degrees of total advance, you can increase that, probably by 6 - 8 degrees. You can certainly dial in too much and start to detonate, but move the distributor in increments of 2 degrees until you are not seeing any more increase in WOT RPM. Then back up one 2 degree step and you are at your best advance. Even if you hear some pinging on a really hot day under heavy load, you can dial the advance back while one the water by loosening one bolt. Takes 2 minutes and one wrench.

Get the most out of your boat by tuning for max power. As long as you aren't detonating, you aren't too far advanced on timing.

 

[milkman250]

Re: timing advance

No my intial timing at idle is 8*btdc and at 3000 rpm is at 18*, so that is a total of 10* advancing, should it advance more than that, sorry for the confusion

 

[milkman250]

Re: timing advance

Any thoughts about that, or is that about rite for my engine, I read on one of theses forums about engine advancing to 28* or in my case another 20* from my 8* btdc at 3000 rpms, this has me really frustrated cause I know their is more potential in my motor if it is suppose to advance this way, thanks for your help

 

[gbeltran]

Re: timing advance

From the factory there is 12 degrees of advance in the distributor. That's how 6 initial becomes 18 at speed. With your initial set at 8 you should see about 20 total. You can bump it more if you're looking to do so, might get kind of hard to start when you have more than 12 initial. Only other way to keep the 8 and have more total would be to remove the distributor and have it recurved.

What potential are you looking for? It's a 160 or so HP engine. More timing might give you what, a few hp? I just asking....

 

[milkman250]

Re: timing advance

Thanks for the info, just been playi
n around with boat and learning also. I had my wife drive boat at wot and we were running 4200 rpms and while she was driving I rolled the distributor and hit 4600 with no problem, guess I'm over advancing it abit. Just didn't think there would be that much motor left.

 

[gbeltran]

Re: timing advance

4200-4600 is the recommended WOT range for the engine, I don't see a real problem with running it at the high end of the scale. Just listen for detonation and check the plugs for any signs of it. What was the timing when you ran it up with your wife driving?

 

[milkman250]

Re: timing advance

I'm not sure what the timing was at at wot, but when we came back down to idle it was at 16*. It kinda worried me about trying to start engine with that much advance, don't want to tear up my starter. Don't get me wrong the boat runs smoothly with no stalls or anything, gets up on plane with no prob, but twisting the distrubutor makes the boat awsome and a thrill to play around lol

 

[Lou C]

Re: timing advance

The V-6s do run less centrifugal advance than the V-8s do, I'm not sure if they are more prone to detonation, but I would not advance it beyond 6* BTDC for a stock engine, because these engines run rich and cool, and you will get carbon build up, which increases the octane appetite of the engine and results in greater likelihood of detonation. The question is, can you really even hear detonation in a boat over all the wind noise, etc, not like in a car...
I checked my full advance by the book with an advance timing light in the water, and it was right on the specs...

 

[milkman250]

Re: timing advance

Thanks for all the help guys, I got an omc shop manual today and I will set everything back to factory specs