Timing help 2004 4.3 merc carb

[sickwilly]

I cannot get to 10 degrees BTDC.

I just finished rebuilding my carb and reinstalling it on the boat. Thus, I am trying to do the timing, idle, and mixture.

I have the mixture screw at 1.5 turns out from fully seated.

I put the boat in base timing mode from running a wire from the purple and white wire to the negative ground on the alternator.

I am checking timing by two white lines I painted on the main crank pulley and a little area that protrudes from the block.

When I checked the timing, it was at 55 degrees BTDC. I could see that the previous owner or someone had loosened the distributor and turned it.

When I turn the distributor clockwise, the degrees of advance lower, but the motor starts running really bad. I understand that this is how it should run in base timing mode, right?

In order to keep the boat from dying, I am tightening the idle screw.

Once I got in the range of 25-30 degrees BTDC, if I rev the throttle at all, I get a small backfire through the carb.

I kept pushing on, determined to get to 10 degrees, but eventually I got a backfire through the carb when turning the idle screw.

This is when I decided I need help, or to bring the boat to a real boat mechanic.

Any advice would be appreciated.

 

[sickwilly]

Re: Timing help 2004 4.3 merc carb

If it mattes, the symptoms as to why I decided to rebuilt the carb are the following:

1- hard to start
2- after started, until warm, giving it any gas either kills the engine or causes an occasional backfire through the carb
3-hesitation when trying to accelerate
4- dieseling

 

[Don S]

Re: Timing help 2004 4.3 merc carb

Are you sure you have the timing light on the #1 spark plug wire?

 

[sickwilly]

Re: Timing help 2004 4.3 merc carb

Yes, I believe. There is a 1 on the distributor and a 1 on the intake manifold. If looking at the motor from sitting in the boat, I am on the first plug wire for the first spark plug on the right side.

I tried attaching the gun on the wire just off the distributor and then again along the side of the block.

At the advance of 55 whether or not I disconnected the wire from the purple and white one made no difference in how the engine ran, but once I got into the 20s it did.

Its a MAP brand timing light.

 

[Don S]

Re: Timing help 2004 4.3 merc carb

Number 1 on the distributor cap doesn't mean much if someone installed the distributor wrong, go by #1 cylinder and hook the timing light on the wire close to the spark plug.

 

[jtmarten]

Re: Timing help 2004 4.3 merc carb

Chevy #1 is usually left side. You wouldn't be able to start it if it was 55* advanced.
As Don said, the #1 on the dizzy means nothing as long as the wires are in proper order.

 

[sickwilly]

Re: Timing help 2004 4.3 merc carb

I am on the right one. Maybe I will try a different timing gun later.

I am assuming, but guessing from your response, running at 55 degrees advanced is not realistic -- something is amiss?

Am I ok pointing the gun at the main pulley from under the power steering pump, where I painted a white mark on the pulley and the area inside of the pulley?

Where do you shoot your timing on a 4.3 merc?

 

[jtmarten]

Re: Timing help 2004 4.3 merc carb

Where did you paint a white line?
You should have a groove in the balancer, and a timing tab that has timing marks on it. The bigger 'V' on the tab is 0*. If you have an advancing timing light, set it at 10*, adjust the dizzy until the groove is in the 0* 'V'. If you have a standard light, the smaller 'V' on the tab next to the 0* 'V' is 10* advance.
If you're trying to set timing from the side, I don't think you're going to be at a good angle to see the marks.

 

[Don S]

Re: Timing help 2004 4.3 merc carb

There are 60? of rotation between each plug wire on the cap, and you are well within that range by being 55? off.

You need to start by finding #1 TDC on the compression stroke, then looking at your rotor and make certain that #1 plug wire is aimed at the rotor. Then you need to make sure you have all the wires in the correct order. Check each and every one. If you can't trace it by hand to be sure it's the right one, use an ohm meter and check the wire for continuity to be sure you have them in the right order.

 

[Don S]

Re: Timing help 2004 4.3 merc carb

and a timing tab that has timing marks on it.

He doesn't have a timing tab marked in degrees on his engine. He has the composit timing cover with a single groove in it, and a single line (groove) in the harmonic balancer.
Here is a picture from the Volvo manual so you can see where the marks are.

 

[jtmarten]

Re: Timing help 2004 4.3 merc carb

Gotcha
With that setup, an advancing light would be a huge benefit!

 

[sickwilly]

Re: Timing help 2004 4.3 merc carb

Thanks for the pic. I definitely did not find that. I now know that I am simply not seeing what I need to see. Maybe I will have to unbolt my bench seat to find that view, but seeing it in a picture format should help greatly.

I can't look until later tomorrow or Monday. The family is taking me canoeing for father day. I am definitely itching to get out there and work on the boat again.

I really appreciate the help!

 

[sickwilly]

Re: Timing help 2004 4.3 merc carb

The picture was worth a 1000 words. I got it!

It was darn hard to see and shoot, but I got it. I almost had to remove the rear bench seat. I shot it with the right eye, gun to the left, then the left eye gun to the right. I am somewhere between 9.25 and 10.75, hopefully dead on 10 degrees advanced.

I then got my idle set where I think it should be, and tightened my mixture screw till the idle seemed to fall a little, then backed out a half turn.

I know I next need to do the idle and mixture again with the boat in the water, again with the base timing mode jumped.

I have a brand new cap, rotor, and plugs. I guess I will do these next, although I am interested to see how it run with just the carb rebuild, timing adjustment, etc. However, I guess if I am going to get it dialed in, I should do so with all new parts on it, right?

Anyway, thanks for all the help! You all have a big fan in Middle Tennessee.