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I wrote earlier about timing advance, I was told to check at full throtle...I'm running the 2 blue springs and the smallest bushing...In order to reach full advance (34 deg.) (its marked on the balancer) the initial advance is way off the tab (about 20 degrees if the tab went that high).Engine seems to run ok , no ping. Any ideas why this would be (20 deg+ initial). My guess is that it could be a tooth off.
10-07-2003, 11:17 PM
Does your distributor have vacuum advance? If so, make sure it is disconnected when you check the timing. The smallest bushing (Red) should give you 28 degrees of mechanical timing. If you are setting your total at 34 degrees then you initial should be at 6 degrees (34 - 28 = 6). Check your TDC mark on your balancer to make sure that it is truely at 0 degrees (TDC) when the piston is at top dead center.
No Vac Advance...at ide, the timing mark is way off the tab - about 20deg....Its in a boat so I can checkat idle and under acceleration. There's a second mark on the balancer which represents 34 deg....It looks to me as if the distributor is only giving me about 10 deg of advance instead of the 25 deg it should.
The setup I'm looking for is what you descibed 28 deg mech. and 6 initial for 34 total.
What I'm getting is about 12 deg. mech and 22 deg. initial.
Its in a jet boat - Olds 455
10-08-2003, 11:54 AM
What kind of timing light are you checking the timing with? Make sure that the light you are using is not an adjustable type timing light. The dial back and digital type lights are very prone to noise and will give you inaccurate readings as well a showing things that is not happening.
10-08-2003, 03:49 PM
How does the motor run? Does the motor start hard after it is warmed up and then shut off? It sounds as if there is some noise getting into the timing light showing some odd ball reading. Try powering up the light with a different 12 volt source, a spare battery or power pack that is not attached to the boat. Make sure that you have the pick up of the timing light down by the plug away from the other plug wires. If possible try another timing light that has a metal case around the pick up not a plastic one. These are a few other things to look at.
Motor runs ok, no hard start or run-on. I do have a problem getting all the way into the throtle... The last 1/4 of the secondary has a bog, I assume its from the timing issue....Timing light does have a plastic pickup...The mark doesn't bounce around... At full throtle its sits right at 34deg. (22 int. + 12 mech.)
I don't have plan to go out any time soon (can't try a different power source & timing light at full throtle). Although i will at idle.
Any other ideas or things to look for assuming the timing light IS reading corectly.
10-08-2003, 11:13 PM
Check your TDC mark on your balancer to make sure that it is truely at 0 degrees (TDC) when the piston is at top dead center on the compression stroke. Install a fulley degreed timing tape on the balancer so that you know exactly what the timing is really doing.
The balancer is marked all the way around...I'm installing a new cam this weekend, when I degree it, I can confirm that 0 on the balancer truly is TDC.
Regardless of whether 0 truly is 0, I can watch the mark move (while a friend drives the boat) only anoher 10 degrees or so from its idle setting....At idle the timing shows about 22 deg BTDC...When he gets into the throtle, It reads exactly 34. This leads me to believe the distributor is putting out less than half of what its supposed to.
Perhaps I can find the issue on the cam change, but hoping to solve the problem first.
Could something be hangging up on the advance mechanism?
10-10-2003, 04:03 PM
It could be. Check the nut on the bottom of the weight plate that holds the bushing in place. There is a washer under the nut, that might be limiting the advance. When you have the distributor out look at this. Don't rule out the timing light problem I had mentioned previously.
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