Ignition Timing Question

[Haody]

So I came across something strange when i was adjusting the advance timing on the ole Sea Ray (1984 Sea Ray 5.7 L OMC). At idle, it was at -5 degree, at 3000 RPM, it was showing about 10 degrees. So i adjusted the total advance at 3000 RPM to 32 degrees per spec. The boat used to run WOT at about 3700 RPM, but now at 32 degrees, it's hitting 4200 RPM. It sounds great. However, now when I check the timing at idle, it's showing like 20 degrees. It's supposed to be 8 degrees. Anyone have any ideas why? Should I be concerned? Thanks in advance.

 

[Bt Doctur]

probably because the timing chain has a lot of play in it.

 

[scoflaw]

Why type of advance setup does your distributor have?

 

[hottoddie]

Sounds like the advance springs in the distributor are stuck or broken allowing the timing to be erratic. Part or those old distributors are hard to come by so the best solution is to install a marine HEI distributor such as Delco Mallory or DUI (Davis Unified Ignition). Total parts cost around $400. BTW the timing at full advance (around 3000 rpm) is the most important.

 

[CliffA]

you can install a 'Delco Voyager EST 'marine ignition system for under $400.....that includes everything including the distributor....I swapped out a Mercruiser Thunderbolt V ignition with the Delco system on a previous boat....pretty easy swap and was one of the best things I ever did for that boat....

http://www.michiganmotorz.com/delco-voyager-marine-electronic-distributor-p-119.html

 

[Haody]

I can't find the brand, but i think it's a new(er) distributor. it doesn't have points. Someone before me converted to an electronic system. The full advance at 3K is 32 degrees, around what spec recommend and it runs good. Guess it's okay to leave it as is yeah?

 

[scoflaw]

Look under the rotor, if it's got weights and springs, maybe just fetched up

 

[CliffA]

I would be careful about advancing the timing too much....you could start getting early detonation and not hear it due to the noise of the engine and the engine hatch....that could lead to damage to the pistons and push rods.....

cliff

 

[scoflaw]

I would be careful about advancing the timing too much....you could start getting early detonation and not hear it due to the noise of the engine and the engine hatch....that could lead to damage to the pistons and push rods.....

cliff

Very good point, 20* at idle is too much. Fix it now or pay later.

 

[Sublimetime]

The advance weights are fouled up and not returning to center at idle. clean and lube, work the arms back and forth.

 

[CliffA]

The advance weights are fouled up and not returning to center at idle. clean and lube, work the arms back and forth.

I found that 'PB Blaster' does a good job of cleaning and freeing the weights.....

cliff

 

[Haody]

this is what it looks like under my distributor cap. I don't see any weights unless it's underneath.

http://www.iboats.com/mall/partfind...&gd_poid=242881&gd_row=7&session_id=470774429

 

[scoflaw]

OK, so it looks like that's the part that went south. You should call their tech line and run it by them.

 

[Haody]

OK, so it looks like that's the part that went south. You should call their tech line and run it by them.

Thanks. Let me see who the actual manufacturer is. That was just a stock photo to help explain what it looks like.

 

[cmount1]

The weights will be underneath the plate shown in the picture. Grab the rotor and try and rotate it CW, it should spring back to it's at rest position freely. They can get gummed up and sticky.

 

[scoflaw]

The weights will be underneath the plate shown in the picture. Grab the rotor and try and rotate it CW, it should spring back to it's at rest position freely. They can get gummed up and sticky.

Yes, and get that squared away first before moving on to the part pictured

 

[Sublimetime]

weights and springs for advance are located under the plate that the plate you shown in part is bolted to. Try the twisting of rotor to see if it returns all the way on its own like mentioned above.

 

[Haody]

weights and springs for advance are located under the plate that the plate you shown in part is bolted to. Try the twisting of rotor to see if it returns all the way on its own like mentioned above.

When I turn the rotor clockwise, should there be a lot of resistance? Just want to know just so i don't eff it up and break something.

Update: I can't turn it. Also, I lied, this is what it looks like under the cap.

http://www.ecklerstrucks.com/chevy-and-gmc-truck-electronic-distributor-ac-delco-1988-1995.html

better view, there's nothing under the plate.
http://www.ebay.com/itm/Distributor...iter_Display:5.7L&hash=item1c54b7ce58&vxp=mtr

 

[cmount1]

With that distributor you set the base timing at idle and the advance curve is controlled by the ignition module. Otherwise your fighting the module when attempting to time the engine at speed.

 

[Haody]

With that distributor you set the base timing at idle and the advance curve is controlled by the ignition module. Otherwise your fighting the module when attempting to time the engine at speed.

Just so I understand...Just worry about setting the idle timing and let the module do it's thing.