Timing for 1987 OMC

[larry1167]

I have a 1987 OMC I/O with a 350 V8. It's a Cobra Outdrive. I am trying to determine the correct timing for this engine. My manual refers to two different models for this year and corresponding degrees BTDC...... 574AMFTC at 10 degrees and 574AMARY at 8 degrees. I am the second owner of this boat and I don't know which model engine I have. Nothing in the manual gives an explanation of these two different models. Does anyone know what these two different figures stand for? I assume it may be the type of carberator but I'm not sure. I just timed my boat this weekend and it sounded good at 10 degrees so that's what I went with. I would like to know for sure. Thanks in advance.

 

[bruceb58]

Re: Timing for 1987 OMC

here is a chart that shows what everything means:

http://www.sterndrive.info/model_numbers.html

It does not say what the difference is between the ARY and FTC though.

 

[JCF350]

Re: Timing for 1987 OMC

DISTRIBUTOR ASSY., Prestolite, IBM-7013D: ARY model

DISTRIBUTOR ASSY. Prestolite, IBM7013C: except ARY models

DISTRIBUTOR ASSY., Mallory: except ARY models

 

[larry1167]

Re: Timing for 1987 OMC

Thank you JCF350. I have a Prestolite screw down distributor cap. Do you know if that is an IBM-7013D or IBM-7013C? I searched the net but could not find either part number. Thanks again.

 

[larry1167]

Re: Timing for 1987 OMC

I believe I found it. Per information on line, I have an IBM-7013C distributor assembly which correlates to 10 degress BTDC. I attached the document I found but not sure if it will attach to this post. My boat sounded best at 10 degrees so I am good to go. Thanks again. This is a great web site.

 

[bruceb58]

Re: Timing for 1987 OMC

So what do you mean by sounded best at 10 degrees? Are you talking about at idle?

 

[JCF350]

Re: Timing for 1987 OMC

Check the numbers on the distributor first. BRP only shows a screw down cap picture so don't assume.

 

[Boatin Bob]

Re: Timing for 1987 OMC

Larry...do you not have a model/serial plate on one of your rocker covers or the thermostat housing?

 

[HT32BSX115]

Re: Timing for 1987 OMC

Howdy,

According to my OMC service manual,

The 574AMFTC engine should be timed using 89 AKI fuel 10* BTDC and 5* BTDC using 86 AKI fuel....point dwell angle is 30* +/- 2* gap is about 0.018" or 0.46mm

If you're running regular gas and you time it for midgrade you might find out it's advanced a little too much when you pop a hole in a piston...

http://www.torquecars.com/articles/fuel-octane-ratings.php



Cheers,

 

[larry1167]

Re: Timing for 1987 OMC

Yes, I timed it at idle at 10 degrees. Aren't you supposed to time at idle?

I run 89 octane(midgrade) in my boat all the time. Therefore, I should be at 10 degrees, correct? I didn't know I could run it on 87 octane. I may take this into consideration with gas prices.

I am second owner and I believe the serial number was on the thermastat housing but it's gone now.

Where do I look on the distributor assembly to find the distributor model number?

 

[bruceb58]

Re: Timing for 1987 OMC

How it sounds at idle is pretty meaningless. The timing at idle just sets the start point since the centrifugal advance adds a lot more as you go up in RPM. Its the total advance that is critical and you don't want too much so that it pings under load.

 

[larry1167]

Re: Timing for 1987 OMC

Bruce - I am a weekend warrior. You are starting to go above my head here so I apologize for my lack of experience. My manual states to set the timing at 10 degress BTDC. I set this 10 degrees at idle per my octane rating. Should I be checking the timing another way? I took the boat out this past weekend. It ran like a champ. I did not hear any knocking or pinging. Temperature of the engine was within standard.

This winter I changed the plugs, re-set the point gap and inspected the distributor cap. I didn't have to adjust the timing because when I checked it, it was already at 10 degrees.

Let me know what you think

 

[JCF350]

Re: Timing for 1987 OMC

All you need to know is where the timing gets set at by the book. Don't worry about the the other stuff (the factory has done that already).

Since you re-gapped the points you changed the timing which is why you need to make sure it is set correctly. In your case it depends on which distributor you have. Whose numbers would be on the outside of the distributor housing.

 

[larry1167]

Re: Timing for 1987 OMC

Thank you JFC350. I was doing some research on advance timing and didn't want to go there. I will check the distributor housing when I get back to my boat in a few weeks. Thanks to everyone. I sure learned a lot. Maintaining a boat yourself sure is a lot of work but it's fun and a challenge, which is cool.

 

[bruceb58]

Re: Timing for 1987 OMC

Bruce - I am a weekend warrior. You are starting to go above my head here so I apologize for my lack of experience.

I understand. My point is that you set it where it should be set and not by what sounds good at idle. You set it at what is stated in the manual so that the total advance will end up being correct.

 

[larry1167]

Re: Timing for 1987 OMC

Bruce- I see what you were saying. We're on the same page now. I am good to go. Thanks for your time.