Timing for stock 2F on modern fuel? (2 Viewers)

[e21pilot]

I recently replaced a leaking VCV near the distributor on my 1980 FJ40. The leak went away and the idle quality is better but the engine is running a little like the timing is off. I wonder what the suggested ignition timing is for a stock 2F running on modern 87 grade (10% ethanol) fuel and what is the best way to set the timing. I would like to make sure my timing is on before I investigate anything else.

 

[thebigredrocker]

When in doubt I see what FJ40Jim had to say:

Some quick facts to help with actual timing settings:

The 79-80 dissy has total mech advance of 20-24*. This number varies depending upon the degradation of the stop pin bushing.
Primary vac advance of appx 18*.
Sec vac advance 6*.

If all 3 advances are available, there could be 48* of advance added to the base of 7*, yielding total crankshaft advance of 55*.

The generally optimal timing for the open chamber cylinder head is 36-38*

This brings up vacuum setup option #3.

Connect distributor sec vac advance to carb ported vac. Giving max advance of 6+(20 to 24), total available 26-30*.
Set base timing at 7*, total crankshaft advance is 33-37.

That is a stock 79-80 dissy. It is a good unit, as long as the vac advancer still works. They are old enough now that the failure rate is ~50%. Get a mityvac tester and see if the two vac fittings will hold vacuum. also, pull off the dissy cap and verify that when vac is applied, the plate moves inside the dissy.

If they are both good, then connect the vac advance hose to the inner fitting, closer to the dissy body.

If only the outer fitting test good, then connect vac there and bump up the idle timing a couple degrees.

If neither fitting holds vac, then consider getting a used 81-87 dissy and engine side cover.

On the dissy cap are 2 hoses. The big red one should go to a small filter inside the firewall. The smaller one that is currently hanging out should go up to the top of the air cleaner. It is important to have the hose connected to air cleaner, because it will pull air through the dissy to keep the electrically charged (ionized) gases moving out of the dissy. Ionized gas is aggressively corrosive and eats the innards of a sealed dissy.

 

[thebigredrocker]

if you have a basic timing light you move your dizzy until the strobe flashes on the 7 degree mark on your flywheel(it's a bb pressed into the flywheel on an F). I assume your 2F is similar. So slightly to the left of the bb will be 6 degrees.

If you have an adjustable timing light you can set the advance to your desired number(6 degrees?) now you'll want the strobe to flash on the flywheels TDC mark.

Here's a pic of timing marks on an F flywheel. Flywheel spins clockwise so the 7 degree bb shows up first.

 

[1911]

My 1980 likes more base advance, about 10 degrees - but I'm completely de-smogged and live at about 1,000' elevation. YMMV.

 

[White Stripe]

Before you mess with timing too much make sure your vacuum advance operates and that your distributor is in good shape.

 

[thebigredrocker]

In regards to what White Stripe pointed out, this is where an adjustable timing light could help(I think) determine how all advance "influencers" are behaving. With your engine revved up, quickly adjust your dial(mines digital) until your strobe finds the 0TDC mark (30is-50ish degrees depending how you're set up). I don't own a 2F yet but I gather Jim caps off the primary canister to get the tatal down to his goal of 36-38 total. So perhaps write down where base and total timing are at before you change it.

 

[cult45]

Is there no variation due to the lower octane rating of unleaded fuel? I try and run premium every second tank [filling up when it hits 1/4].

 

[1911]

Is there no variation due to the lower octane rating of unleaded fuel? I try and run premium every second tank [filling up when it hits 1/4].

A 2F is such a low-compression motor that octane doesn't matter much if it all.

 

[cult45]

A 2F is such a low-compression motor that octane doesn't matter much if it all.

And similar era carbureted cast-iron engines would be the same?

 

[White Stripe]

You would only need premium if you advanced your timing so much that its pinging on regular. Otherwise it does nothing.

 

[1911]

And similar era carbureted cast-iron engines would be the same?

Not all similar-era engines are as low-compression as the F and 2F; they were designed to be compatible with poor-quality third-world petrol.

 

[cult45]

Sweet, thanks fellas!

 

[Curt]

I generally run on premium fuel timing set to 10* trollhole dizzy. Another advantage of premium fuel can be ethanol content or lack of.

 

[65swb45]

Is there no variation due to the lower octane rating of unleaded fuel? I try and run premium every second tank [filling up when it hits 1/4].

There are a number of variables, including the condition and adjustment of the cam, valves and overall compression of the engine that will play into the timing equation along with dizzy condition.

IH8 one size fits all answers.