Volvo Penta GM 5.7 TBI low power at take-off

[alldodge]

that you actually want to run as much advance as you can without pre-detonation. what are your thoughts?

Yes

 

[Scott Danforth]

got it! move the 4th mark on the right to the V notch! I thought that but after talking advance and retard timing CW CCW front back I get mixed up! thank you for straightening me out. I have read a few posts stating that slightly retarding the timing increases low end torque while sacrificing top end. howevrer my understanding of the combustion process is the opposite. that you actually want to run as much advance as you can without pre-detonation. what are your thoughts?

You are confusing ignition timing and cam timing

Yes, retarding the cam timing will move the power band lower (sooner) providing a bit more torque on the low end

 

[spomey]

You are confusing ignition timing and cam timing

Yes, retarding the cam timing will move the power band lower (sooner) providing a bit more torque on the low end

I will keep that in the memory banks but I think that is more than I am willing to do, it seems stuff is always more complicated or causes other issues LOL. I will try the 8 degrees BTDC timing do you agree with that?

 

[spomey]

Yes

Wow, I advanced the timing on the boat to I don’t know how far 8-12 degrees there are no marks on the block or the vibration damper. But damn what a difference!

Comes out of the hole pretty damn good for a 4400 lb boat and the top speed is around 40-44 which is too fast for the choppy lakes around here! At acceleration there is a just a very small hiccup around 1500 RPM and at idle there is a miss (feels like a single cylinder). Top RPM is around 4400 but I have heard it should be around 4800 (not quite sure)

My plan is to run it like it is and hope that due to timing maybe carbon or gunk is causing the miss and it will burn out.

There really isn’t a good way to mark the vibration damper its just too congested in that area, there is a water circulation bump attached to the crank. So I was just going to eyeball it and do timed runs of 0-30 mph. and leave it where I get the lowest time.

 

[bruceb58]

Wow, I advanced the timing on the boat to I don’t know how far 8-12 degrees there are no marks on the block or the vibration damper. But damn what a difference!

Comes out of the hole pretty damn good for a 4400 lb boat and the top speed is around 40-44 which is too fast for the choppy lakes around here! At acceleration there is a just a very small hiccup around 1500 RPM and at idle there is a miss (feels like a single cylinder). Top RPM is around 4400 but I have heard it should be around 4800 (not quite sure)

My plan is to run it like it is and hope that due to timing maybe carbon or gunk is causing the miss and it will burn out.

There really isn’t a good way to mark the vibration damper its just too congested in that area, there is a water circulation bump attached to the crank. So I was just going to eyeball it and do timed runs of 0-30 mph. and leave it where I get the lowest time.

Since you don't have marks, get an advance timign light. You adjust the knob on the timing light until the marks for 0 line up and the dial on the timing light tells yo what the advance is. Conversely, if you want 8°F, you set the dial on the timing light to 8°F and rotate the distributor until you have the marks lined up on the crankshaft.

What you have done right now is set the timing to some random spot and you may have detonation without even knowing it. I would set the engine in base timing mode and set the engine to the proper spec. If you don't know how to do that, get someone who knows how to and stop running this boat until you do so.

 

[spomey]

Since you don't have marks, get an advance timign light. You adjust the knob on the timing light until the marks for 0 line up and the dial on the timing light tells yo what the advance is. Conversely, if you want 8°F, you set the dial on the timing light to 8°F and rotate the distributor until you have the marks lined up on the crankshaft.

What you have done right now is set the timing to some random spot and you may have detonation without even knowing it. I would set the engine in base timing mode and set the engine to the proper spec. If you don't know how to do that, get someone who knows how to and stop running this boat until you do so.

in an automobile when you detonate there is a very pronounce "pinging" wont the boat do the same thing? I have listened closely for it. I understand what your saying, I do, and I know i am..randomish in my timing placement however you can estimate fairly closely, also I can measure the circumference of the vibration damper, and doing some math figure the distance 8 or 10 or 12 degrees is and mark that as well. a timing light would be easier though, i will look into them.

Since you don't have marks, get an advance timign light. You adjust the knob on the timing light until the marks for 0 line up and the dial on the timing light tells yo what the advance is. Conversely, if you want 8°F, you set the dial on the timing light to 8°F and rotate the distributor until you have the marks lined up on the crankshaft.

What you have done right now is set the timing to some random spot and you may have detonation without even knowing it. I would set the engine in base timing mode and set the engine to the proper spec. If you don't know how to do that, get someone who knows how to and stop running this boat until you do so.

Since you don't have marks, get an advance timign light. You adjust the knob on the timing light until the marks for 0 line up and the dial on the timing light tells yo what the advance is. Conversely, if you want 8°F, you set the dial on the timing light to 8°F and rotate the distributor until you have the marks lined up on the crankshaft.

What you have done right now is set the timing to some random spot and you may have detonation without even knowing it. I would set the engine in base timing mode and set the engine to the proper spec. If you don't know how to do that, get someone who knows how to and stop running this boat until you do so.

I will get ahold of a programmable timing light. I understand what your saying, but I truly believe I am close to 10 degrees. also I am at 4900 ft so power is down 12% ish. so you get away with alot more. One issue that I have is that at times in neutral my idle stays around 1800, and that may be timing related.