AQ125A timing issue

[ENCMJB]

Hi all. This is my first post to this forum. My question is concerning a 1984Volvo Penta AQ125A. Every manual I can find tells me that the timing is to be set at 10 deg BTDC. When I set mine there it runs, but poorly. It sounds like it is about to fall on its face. This engine runs like a champ set at 20 deg BTDC. I am at a loss. Everything in the ignition system is new. New points, condenser, cap, rotor, plugs, wires. The dwell is set at 60, which is within specs (62+/- 3). Any ideas or thoughts would be appreciated.
Matt

 

[captmello]

Re: AQ125A timing issue

Welcome.

Have you checked or replaced the timing belt? Has the engine ever run good for you before.?

 

[Don S]

Re: AQ125A timing issue

Do a compression test.
You also have to have the dwell set properly. While the book says 62 +/- 3? 62 or 63 makes them run great, while 60? not so great. It's the fine details that makes the rubber band engines work the best.
You get the dwell right, the timing right and the carb adjusted right, with good compression, good timing belt and good spark plugs wires, and other details, and the engiine will run perfectly.

Everything has to work together at the same time to make an engine run perfect.

 

[ENCMJB]

Re: AQ125A timing issue

It has a new timing belt, and when installing the belt all the marks lined up as they should have. I recently acquired this engine in a non-running state, so I can't give you an honest answer on how well it has run in the past, as I am starting from scratch here. However, I can tell you that a compression test was the first thing I did and although I don't remember what the numbers were the compression was fine.
Maybe I should try to get an extra 2 or 3 degrees of dwell and see what that does for me. I honestly don't think it will make up for that much of a gap but I'll give it a shot.
Also, ever since I messed with the timing, she will not restart when the engine is hot. I have to wait a while before restarting. I didn't have this problem before playing with the timing.

 

[ENCMJB]

Re: AQ125A timing issue

Finally got around to checking the timing belt. It was dead on where it is supposed to be. Now I am completely at a loss. Anyone ever heard of a timing light being suspect?

 

[captmello]

Re: AQ125A timing issue

Did you adjust your dwell and try readjusting the timing like Don S mentioned?

When you say it "Runs like a champ" @ 20 deg BTDC, is that on the water at WOT or reving on muffs in nuetral?

It would would help to know the compression numbers as well.

 

[Maclin]

Re: AQ125A timing issue

This sounds like the advance mechanism inside the distributor is sticking or frozen.

With the cap off you should be able to move the rotor some and have it snap back. This action should be very smooth, and the snap back be tight.

If it is stuck then the distributor is basically at full advance all the time, so whatever initial advance it is set at is all she gets. 10 degrees is not enough at anything above idle. Even 20 degrees is not enough at speed, but 20 degrees initial advance is too much and it will be hard to start warm and try to kick back.

 

[Maclin]

Re: AQ125A timing issue

And Don S is right about the dwell spec, the highest dwell within the spec that you can attain will have that much better spark. Check the advance action and see what you think. Then once you are sure that is correct then you could try to fine tune the dwell.

 

[bruceb58]

Re: AQ125A timing issue

Did you set the dwell with a dwell meter? Hopefully not just gapping the points.

 

[mcleaves]

Re: AQ125A timing issue

Had this exact problem with this engine and then Uncle Don sat me down and explained the world of points and dwell to me. Ran great afterward.

Check and set the dwell as Don said.

M

 

[ENCMJB]

Re: AQ125A timing issue

I did use a dwell meter and right now I am at 61. Tomorrow I will adjust for an extra 1-2 degrees of dwell and see if that helps. I will also take a look at the advance mechanism to see how that is working. I seem to remember it being okay, but I will double check it. Thanks for your help. I'll let you know what I come up with.