Basic Ignition Timing vs. Strobe Ignition Timing???

[DarrellK]

Seeking clarification (and education).

1978 AQ120B. Seloc Manual says:

Ignition Timing Basic..... 10 BTDC
Ignition Timing Strobe..... 36-38 degrees @ 2800

Original Operators Manual says:
The same for Basic, but
Strobe setting says - 61.6 - 80.0 r/s (3700-4800 rm)....36-38 degrees BTDC

I set the timing with my strobe light, engine at idle, to 10 degrees BTDC. I think I did it incorrectly.

Do I need to set the rpm between 3700-4800 and then set the timing to 36-38 degrees BTDC?
What is "Basic Timing"?
What is the "2800" in the Seloc manual? If it's RPMs, why is it so different than the Operators Manual spec of 3700-4800?

Thanks

 

[Scott Danforth]

Re: Basic Ignition Timing vs. Strobe Ignition Timing???

take the seloc manual and throw it away.

following your original OM you set it at idle to 10 BTDC. then you run the RPM up to 3700RPM and check (make sure you are in water and not on the muffs). your advance should be between 36 and 38 degrees (26 degrees of mechancial advance)

your base timing is 10 degrees. the advance curve adds 26-28 degrees for a total of 36-38

the seloc manual differs because it sucks like a Clymor manual

 

[DarrellK]

Re: Basic Ignition Timing vs. Strobe Ignition Timing???

Thanks Scott. That all makes sense. Heading to lake tomorrow and will check w/o muffs.

Merry Christmas

 

[bruceb58]

Re: Basic Ignition Timing vs. Strobe Ignition Timing???

Do you have an advance style timing light? If you don't, you may have to put some timing tape on the harmonic balancer to verify the timing at high RPMs if there aren't marks already that go that high.

 

[DarrellK]

Re: Basic Ignition Timing vs. Strobe Ignition Timing???

I do not have an advance timing light. Thanks, that was on my mind. If I recall correctly, the marks only run to 30 or 35.

 

[bruceb58]

Re: Basic Ignition Timing vs. Strobe Ignition Timing???

If they go to 30 or 35, you can probably extrapolate yourself.

 

[Scott Danforth]

Re: Basic Ignition Timing vs. Strobe Ignition Timing???

keep in mind the key is to set the base timing. checking the advance curve is only a check to make sure you are getting full advance

 

[Lou C]

Re: Basic Ignition Timing vs. Strobe Ignition Timing???

The other issue is to make sure the engine is at curb idle (low idle speed) when you set it, because if the idle is too high (like 1000 or slightly higher) on some engines the advance curve may start. Which would lead to the timing being off.
The advance timing light makes it easy to check this. What you do is set the base timing first. Then put the boat in the water and anchor it or tied to the dock, start the engine, hook up the timing light. Run the engine in NEUTRAL at the rpm where the full advance is supposed to be checked. Set the advance on the correct degree setting on the timing light and the mark should be were you set it for the base timing, it takes that into account. On some older distributors, that use mechanical advance systems, you can remove the point mounting plate and lube the advance weights and make sure the springs are OK. Newer ones use electronics for the same function so there isn't much to go wrong, it works or it doesn't. Just make sure you set your base timing at the specified idle rpm.
BASIC TIMING=no advance happening, STROBE the way they are describing it, is when dist advance is occurring.

We older guys who grew up with cars with points and mechanical/vaccum advance distributors learned this stuff back in the day, the electronic ignition generation never had to think of it, so if you have an old boat with a mechanical advance dist you have to ask a few old timers what gives.....

 

[DarrellK]

Re: Basic Ignition Timing vs. Strobe Ignition Timing???

Thanks for everyone's help. I set the timing on the muffs and rechecked it in the water. It was spot on. Regarding the points issue. The boat and engine are a 1978 and it had points. I changed the ignition to a Hot Spark electronic ignition when I replaced the belt.