5.7 omc stalling while shifting

[Nick_1987 5.7 OMC]

Try the 15x13 & see what you get

Try the 15x13 & see what you get

Ok boyzzz we got we going good. Checked dwell, in between 27 and 31. Timing is set to 8* BTDC and idle is between 500-600. I was able to dock nice and easy but after 4 shifts it stalled on me. Luckily I was already in the skills I trhink maybe idle is a tad to low. Anyways, here’s another issue. I get on plane with a little struggle I can see what you guys mean. I get to my WOT and I soon as I hit 3500rpm. There’s a sound like marbles in a washing machine. It scared the **** out of us lol but if I came down on throttle it was good but then I came off plane. At idle it sounds awesome, a lot better then before. And if I kept it at 3500 rpm, the marble sound was still there and then the engine would lose rpm after about 15 sec at WOT and the ticking remained until I came off WOT. If I didn’t come off the throttle and kept it at wot the rpm would gradually come down until the motor came to idle, but it did not die. I’m not sure what is going on but luckily I have you awesome guys!

 

[itsathepete]

So with my timing light I will line the flash up with the 8 BTDC ? I usually run on 87 Oct gas.

you can line up the mark with 8 degrees on the timing cover at idle but it doesn't tell you what your full advance is at 2-3000 rpm. for that you need timing tape or an advance timing light

 

[Lou C]

Right and if you hear a ticking noise it could be pinging which isn’t good. Might have to adjust fuel mixture & make sure the accelerator pump is working. Fuel mix might be too lean. I use at least 89 and at the gas dock they only sell 93 octane. I know the marine engine companies say 87 is ok but you are pushing a huge heavy boat with a small V8.

 

[Nick_1987 5.7 OMC]

Right and if you hear a ticking noise it could be pinging which isn’t good. Might have to adjust fuel mixture & make sure the accelerator pump is working. Fuel mix might be too lean. I use at least 89 and at the gas dock they only sell 93 octane. I know the marine engine companies say 87 is ok but you are pushing a huge heavy boat with a small V8.

Here is a video

 

[Lou C]

check fuel mixture, inspect spark plugs look at center electrode insulator, are they blistered white, if so fuel mix may be too lean
I would also check total timing advance.
Use premium gas no matter what it says in the manual
What is your engine temp? Should be 160-175

 

[Nick_1987 5.7 OMC]

check fuel mixture, inspect spark plugs look at center electrode insulator, are they blistered white, if so fuel mix may be too lean
I would also check total timing advance.
Use premium gas no matter what it says in the manual
What is your engine temp? Should be 160-175

Engine temp is staying between 160 and 175. I have a feeling it’s a bearing on one of the belts. What do you think is causing that rattle? It has nothing to do with rpm. There’s no coralation. It happens at 3500rpm once I back off it’s gone.

 

[Nick_1987 5.7 OMC]

check fuel mixture, inspect spark plugs look at center electrode insulator, are they blistered white, if so fuel mix may be too lean
I would also check total timing advance.
Use premium gas no matter what it says in the manual
What is your engine temp? Should be 160-175

I touched the block and manifold and I didn’t feel no tapping, usually you should. Sounded more from the back of the motor close to outdrive. I have no idea. That’s what I’m asking you guys

 

[Lou C]

You might want to get a mechanics stethoscope they are great for tracking down noises

 

[Nick_1987 5.7 OMC]

What s

You might want to get a mechanics stethoscope they are great for tracking down noises

What should I do when I head to the boat later this afternoon? Adjust something? Maybe retard the Distributer abit because I’m running 87 oct

 

[Lou C]

well now that you know how to adjust it you can retard it slightly and see if that affects that noise, like from 8*-->6* see if that helps. The issue is the more you retard it the more power you lose. So I run mine right at the spec of 6* for the 4.3 and run high octane gas. A lot of people don't realize that these old school engines in marine use can accumulate carbon build up in the combustion chambers and on the tops of the pistons, this has the effect of increasing the octane requirement of the engine. Old school engines, that run cool (160* vs 195* in an auto application of the same engine) and run relatively rich fuel mixes, can be prone to carbon build up.
Is the tank full? when you fill up try 89 or 91 octane if you can find it. I have no regrets using the best I can find. Don't want to burn valves & pistons because of low octane gas.

 

[Nick_1987 5.7 OMC]

well now that you know how to adjust it you can retard it slightly and see if that affects that noise, like from 8*-->6* see if that helps. The issue is the more you retard it the more power you lose. So I run mine right at the spec of 6* for the 4.3 and run high octane gas. A lot of people don't realize that these old school engines in marine use can accumulate carbon build up in the combustion chambers and on the tops of the pistons, this has the effect of increasing the octane requirement of the engine. Old school engines, that run cool (160* vs 195* in an auto application of the same engine) and run relatively rich fuel mixes, can be prone to carbon build up.
Is the tank full? when you fill up try 89 or 91 octane if you can find it. I have no regrets using the best I can find. Don't want to burn valves & pistons because of low octane gas.

so this noise never came until I changed the timing so probably where it’s coming from. So I will drop it to 6. Also! Can this cause the rpm drop aswell?

 

[Lou C]

Not really but if the centrifugal advance in the distributor isn’t working that could do it. Sometimes it’s a combination of problems causing a problem like that

 

[Nick_1987 5.7 OMC]

Not really but if the centrifugal advance in the distributor isn’t working that could do it. Sometimes it’s a combination of problems causing a problem like that

So what else could it be?

 

[Nick_1987 5.7 OMC]

Not really but if the centrifugal advance in the distributor isn’t working that could do it. Sometimes it’s a combination of problems causing a problem like that

Well I retarted the distributed a bit and the sound has disappeared. No more weird noises and no more loss of RPM. I think it dropped from 8* to 6*. New prop is arriving tmr and will test it. I will let you guys know the Rpm’s

 

[Nick_1987 5.7 OMC]

Well I retarted the distributed a bit and the sound has disappeared. No more weird noises and no more loss of RPM. I think it dropped from 8* to 6*. New prop is arriving tmr and will test it. I will let you guys know the Rpm’s

My timing before I even adjusted it was way off, I think it was under 4 or even 2.

 

[Lou C]

Sounds good, you’re going with a 15x13 prop right?
You want at least 4500 rpm with wide open throttle trimmed properly.

 

[Nick_1987 5.7 OMC]

Sounds good, you’re going with a 15x13 prop right?
You want at least 4500 rpm with wide open throttle trimmed properly.

Ok sounds like a plan