1988 85hp Force, advance the timing question

[riptorn]

I don't know too much about Force O\B's and just want to know what can happen if I advance the timing less than 5 degrees? Doesn't look like it was adjusted. I know when I was in my early 20's I had a 1965 50hp merc and advance the timing and it ran like the devil on fire on a 16 by 6ft Humber. I know Chrysler was atrocious with their ignition electrical problems back then but is the Force the same? Man, this 85hp slow for what it is. I have only owned it for one season and it doesn't have a tach in it. Starts and runs good out of the hole but no high rpm. Still have to check the prop pitch. Came with two.

 

[pnwboat]

Re: 1988 85hp Force, advance the timing question

Advancing the timing too much can cause a melted piston. How much is too much? Couldn't say, never wanted to risk damage so I've never tried it.

A tach is very important for tuning to get maximum efficiency out of your motor. When you're at WOT, you should be turning at or close to 5500 RPM. Propeller pitch, weight and shape of the hull also is a big factor in top end performance.

 

[Frank Acampora]

Re: 1988 85hp Force, advance the timing question

Here's three things to think about:

1. In the early 1980s Chrysler reduced timing advance from 32 to 30 degrees BTDC ostensibly because of poor quality marina gasoline.

2. A trusted Chrysler/Force mechanic swears that if you reduce timing to 30 degrees you will never have any problems.

3. Once inadvertently I set timing to advance to 40 degrees BTDC and melted all four piston crowns to some degree. Luckily, aluminum throw-off shorted the plugs and no cylinders were damaged.

So: Do you still want to experiment in advancing timing further than factory specs? Remember: Even high performance dragsters only advance timing about 30 degrees. I can tell you from first hand experience that the difference between 30 and 32 degrees advance is almost nill. You certainly will not be able to notice a difference in top end speed. --- not if everything else on the engine is correctly set.

 

[riptorn]

Re: 1988 85hp Force, advance the timing question

Thanks for the replies. I need to check things out before i do anything. Don't think she's up to 5500 rpm at wot pnwboat. I have a 17ft Bayliner cuddy Capri. Perfect for the small lake we are on.

The thing that bothers me is my wife complains of the smell of gas and oil. Is this normal? I can't remember 15 years ago with that problem with my merc. I've owned a I\O after that.
I had to reset the float on the bottom carb because it was leaking when trimmed up but still the strong smell of gas and oil.

Like you say Frank I don't want to experiment but I know what a lean head burn smells like but my wife doesn't. Is the 85hp similar to the 120hp? Something is not right, eats more gas than my old 165hp I\O. And a 2 times heavier boat.
She's got guts but no speed.

 

[jerryjerry05]

Re: 1988 85hp Force, advance the timing question

Sounds like you need to do some work!!
First get a tach and install it.Then figure out the RPM's at WOT.
My motors came with a 17p and I thought I'd try for more speed???
Changed to a 19p and got 2-3 mph more and the gas went up about 20-25%
So you need to make sure it's set up right.Sounds like the prop is for wakeboarding??
The trim/tilt working?That helps with the speed too.
Gas smell??the ethanol were using can melt hoses and make a mess.
The recirc system clogged and it spills gas in the hood.
Reset the floats.

 

[riptorn]

Re: 1988 85hp Force, advance the timing question

I think your right on all counts. Yes both trims are working good. Like I said I just got the boat last summer and don't know too much about it. Going to do some more reading before I even think about touching the motor. Ya, I think I'll put a tach in though. I have been spending the week waterproofing the boat from the rain with a few design flaws in the windshield, so I got that out of the way.

 

[jerryjerry05]

Re: 1988 85hp Force, advance the timing question

They sell an item called a Tiny Tach
http://www.amazon.com/Tachometer-Ka...FX56/ref=sr_1_1?ie=UTF8&qid=1336943949&sr=8-1 This is the base site for info.Just make sure you get the right one for outboards.

You should really get a good tach in the dash.It helps with performance.

 

[riptorn]

Re: 1988 85hp Force, advance the timing question

They sell an item called a Tiny Tach
http://www.amazon.com/Tachometer-Ka...FX56/ref=sr_1_1?ie=UTF8&qid=1336943949&sr=8-1 This is the base site for info.Just make sure you get the right one for outboards.

You should really get a good tach in the dash.It helps with performance.

Looks cool. Don't understand the wire wrapping?
I'm gonna start another thread about a good small tach for a Force.
Thanks, I didn't realize I was so far out of the loop! I use to have tach's laying around in the shed but do you think I could find them.

 

[Frank Acampora]

Re: 1988 85hp Force, advance the timing question

The wire wrapped around the high voltage lead to the sparkplug is an inductive pick-up. It has a current pulse induced in it by the magnetic field generated around the wire each time the plug fires. ---Electricity 101--

The Tiny Tach counts these pulses