Timing. Degree or vacuum? Or both (2 Viewers)

[LandoNick]

87 fj60 smogged. Did a lean drop with rpm and vacuum hooked up. With the timing set on the “BB” the vacuum gauge said “late ignition timing”. Like right on the line of late timing and normal motor. So like 17 per my vacuum gauge. If I advance my timing to 10 the vacuum goes into the green. Then I have to set the idle back down a bit. My question is. Do you set the timing eight to the “BB” or a vacuum gauge. Also my needle is bouncing a bit. From what I understand it’s a sticky valve? Thanks in advance!

 

[1911]

A de-smogged 2F usually likes more advance, not less. 10 degrees BTDC would be a starting point for me - but I advance mine as far as it will go without knocking or pinging under load; that is the sweet spot for the most power and the lowest engine temperature. Retarded timing will make it heat up quick.

 

[LandoNick]

A de-smogged 2F usually likes more advance, not less. 10 degrees BTDC would be a starting point for me - but I advance mine as far as it will go without knocking or pinging under load; that is the sweet spot for the most power and the lowest engine temperature. Retarded timing will make it heat up quick.

So with a smogged engine. Would that be the same the 10 degrees? Or just keep it at the 7 with the amount of vacuum I have?

 

[OSS]

I wouldn’t use that vacuum gauge as a guide to set timing.
Get yourself an Advance timing light if you don’t have one of those already and set the timing straight on the 7° BTDC dot on the flywheel at idle — then take the engine for a test drive.
Hard acceleration, full throttle, 3/4 throttle, light throttle, full then light then full throttle.

Try to make the engine ping (knock). Pay attention to the feel of torque and power while driving.

If you can’t detect even the slightest bit of knocking, advance the timing 2° more and test drive it again. If the engine has even better power and still zero pinging when ‘torture testing it” just as before — advance it another 2° and test it exactly the same as before.

At some point, you’ll hear knocking if you advance it enough and torque & power will diminish. When it does, back off the timing either 1° or 2° and you’ll be set. (Or use a higher octane fuel).

On my fully smogged 2F, 7° BTDC (right on the timing mark) was overall the best base timing for my engine. - using mid grade octane 89 fuel.

 

[LandoNick]

thanks OSS ! I will give it a try!

 

[1911]

So with a smogged engine. Would that be the same the 10 degrees? Or just keep it at the 7 with the amount of vacuum I have?

Sorry, I misread your post; saw "de-smogged" instead of smogged.

On a stock smogged truck, the starting point for advance depends on your elevation. 7 degrees is for near sea level. Higher elevations require more advance.

 

[g-man]

Have you checked for a vacuum leak? I mean spray carb cleaner around the base of the carb, and around the intake? Around intake plumbing. intake to head gasket. do this while the engine is cold. before it gets hot. Have you removed the carb insulator recently or done intake work?

 

[Spook50]

I was actually in the midst of an experiment to determine the best method for the 3FE. So far (and I caveat this with saying I'm not finished yet but have it on hold until the weather warms up again so there can be some environmental consistency with my results). I'm of the frame of mind that for a 3FE the vacuum method works very well as long as you don't short TE1 and E1 in the diagnostic connector. If you use the degree method, you need to make sure you short TE1 and E1 terminals. The reason behind this for degrees (per the FSM) is that shorting the terminals turns off any computer controlled advance and gives you an accurate measurement to set timing based on flywheel marks. When using the vacuum method you want to keep the advance on (not shorting the TE1 and E1 terminals) so that when you set the timing, you won't end up with pinging once the advance is turned back on.

So far I've set it using the FSM method at 7º, and with my current setup averaged reasonable performance and 14.4 MPG over 6 tanks of gas (I religiously use 91 octane ethanol free). At 10º I noticed much improved performance and an average of 14.0 MPG over 6 tanks of gas. Small price to pay for the performance improvement IMO. My goal with this experiment is to find what setting gives the best balance of performance and fuel economy, then once that's accomplished, set timing using the vacuum method, short TE1 and E1 and see where it sits.

Also for the vacuum method you want to make sure you have absolutely no vacuum leaks.

 

[LandoNick]

So I’m at 171 feet. So I think I will try the 2degree method that was talked about before.

I have a 87 fj60. So I do appreciate the 3fe knowledge. But it blew over my head.

 

[zcostilla]

Buying my FJ62 this week so please forgive the noob question, but how are you checking your torque as you adjust your timing?

 

[LandoNick]

Buying my FJ62 this week so please forgive the noob question, but how are you checking your torque as you adjust your timing?

Might be a little difficult in your case with new 62 but I think it’s just a feeling. More pull through the gears or response from the throttle. If you have owned a 62 before and try and compare the feeling of both. Or stop at your local dyno after each adjustment

 

[zcostilla]

Might be a little difficult in your case with new 62 but I think it’s just a feeling. More pull through the gears or response from the throttle. If you have owned a 62 before and try and compare the feeling of both. Or stop at your local dyno after each adjustment

This is my first cruiser, so I’ll probably set it to stock 7° and start there. I’m sure the FSM will have the step by step, and I already own a timing light gun.

 

[Spook50]

Buying my FJ62 this week so please forgive the noob question, but how are you checking your torque as you adjust your timing?

You can either find a local chassis dyno and spend the money to get legitimate hard numbers, or what I do that seems to be more reliable than the "seat of the pants" is monitor how well it holds speed with a full tank and no cargo (for the sake of keeping the weight pretty consistent) when going up a long incline near me.

 

[LandoNick]

Might be a stupid question. If I have my timing light set in zero and the “BB” set on the pointer that is 7 degrees advanced. To advance the timing by 2 degrees. I would set the advance on the timing light to 2 degrees or 9?

 

[OSS]

You’d set an Advance timing light to 9° to advance the spark two more degrees from seven.
The RPMs increase when the timing advances, so you can hear if you’re rotating the distributor the way you want.

A dumb regular ole timing light is not adjustable, so it flashes when it detects a pulse going to spark plug # 1.
If the needle pointer in the timing window lines up with the timing ball on the flywheel, that’s 7° before top dead center (BTDC). That’s the stock spec.

When using an Advance timing that’s adjustable, you set the timing light to 7° advance (for example) and LINE THE POINTER IN THE TIMING WINDOW WITH THE TDC SCRIBE ON THE FLYWHEEL. Not the regular BB marker.

The Top Dead Center (TDC) scribe on the flywheel is pretty much invisible. You’ve got to mark it with white paint (carefully taped off) so you’ll be able to clearly see it with the timing light strobe.

Just remove the clutch inspection cover and rotate the flywheel around so the TDC mark is on the bottom, tape off a thin line area on the scribe line and paint it (then remove the tape).

Don’t reference the round BB divot on the flywheel when using a user input setting on an Advance timing length. Use the TDC line.

Play with it a bit. You’ll see how it works.

 

[LandoNick]

The 2 degree advance I think was the best for my motor. felt responsive, no ping, idled smooth. My issue still is a low vacuum reading? Is that something that I need to look into more? and if the needle on the vacuum gauge is bouncing is that a sticking valve? I need to adjust my valves I assume. I might have a exhaust manifold leak too.

 

[OSS]

Low vacuum reading is a vacuum leak somewhere which leans out the A/F mixture which can create an overly hot combustion, which can lead to overheating the exhaust valves, which can warp, which will cause a compression leak, which will cause loss of compression, which equals loss of power.

Vacuum leaks on the 2F are BAD for this reason.

 

[LandoNick]

Low vacuum reading is a vacuum leak somewhere which leans out the A/F mixture which can create an overly hot combustion, which can lead to overheating the exhaust valves, which can warp, which will cause a compression leak, which will cause loss of compression, which equals loss of power.

Vacuum leaks on the 2F are BAD for this reason.

but if I turn my timing more advanced the vacuum gauge will go up. So I'm not sure what to think about that

 

[OSS]

Base timing at idle is just a starting point for the entire RPM range the engine is capable of running at.
The 2F timing advance is really simple using springs and weights and a vacuum diaphragm. The timing isn’t perfect at idle at stock 7° because idle isn’t quite as important as where the engine really does it’s work (1800-2800 RPM).
Setting the timing at 7° ensures that it’ll be ok or safe at 1800 or 2500 or 3200 RPM, it doesn’t necessarily mean that it’s the ideal timing for just idle.
Also as timing is advanced at idle, the RPMs will increase which will naturally increase vacuum just because of the faster engine speed.

Below is a direct copy and paste from a comment on a Ford muscle car forum. His comment kind of sums it up:

“Vacuum is a good indicator of engine efficiency, meaning the engines ability to draw air into the cylinders on the intake stroke.

If the ignition timing is off then the combustion process is either too late or too early. Both will leave pressure in the cylinder that is not evacuated fully on the exhaust stroke. That residual pressure means less air will be drawn in on the next intake stroke.”

 

[LandoNick]

How do you be absolutely sure that the mixture screw is exactly where it needs to be? What are some signs that you are off? Either to rich or to lean. Also set all carb setting with the air cleaner on right?