Where are your running your timing - 2F?

[ttubb]

What is the consensus on high altitude timing on a stock 78 2F? Thanks, Terry

 

[Uncle Ben]

Make sure you have a vacuum advance and not retard distributer! 2F's at this altitude can use all the initial advance you can get away with!

 

[SteveH]

I found that having the 'ball' (timing mark) just at the edge of the window works best - so this is 'beyond' the pointer. If the engine speeds up as you twist the distributor, then you're advancing (rather than retarding) I jacked up my timing a lot and then drove to Nebraska once and it was spark knocking like crazy - so you can get too much.

If you have a combination distributor (one with vac adv. and vac retard) disconnect the retard side and put a vented cap on it (to let it breathe as needed, but keep dirt out). Then adjust the base timing ahead some until it's either hard to start the engine, or knocks - and then back it off.

I'm sure others have some other ideas here - so chime in.

Steve

 

[Uncle Ben]

I found that having the 'ball' (timing mark) just at the edge of the window works best - so this is 'beyond' the pointer. If the engine speeds up as you twist the distributor, then you're advancing (rather than retarding) I jacked up my timing a lot and then drove to Nebraska once and it was spark knocking like crazy - so you can get too much.

If you have a combination distributor (one with vac adv. and vac retard) disconnect the retard side and put a vented cap on it (to let it breathe as needed, but keep dirt out). Then adjust the base timing ahead some until it's either hard to start the engine, or knocks - and then back it off.

I'm sure others have some other ideas here - so chime in.

Steve

Perfect tuning procedure!

 

[treerootCO]

I do the same....if you have a CB antenna, radio antenna, you can 'fine tune' it with the circles drawn by the tip. Make very slight adjustments until the antenna stops wagging and you are as smooth as you can be

 

[wesintl]

I think mine was set around 12-14 and I didn't have any smog stuff. I had it as high as 17 before it started pinging.

 

[ttubb]

Thanks!

Reset to about 13 degrees and she is running good. I adjusted the valves yesterday (1000 miles on the rebuild) and it seems very smooth now.
I am at about 10,000 feet here so I don't worry too much about being too advanced.
No ping at 20 mph, 4th grear and W/O throttle so I think I am good.

Thanks again to all. Terry

 

[Rzeppa]

Perfect tuning procedure!

That's what I've been doing for years.

Answer to the direct question, I run about 13° static on my 78, a little more (15° IIRC) on my 71.

 

[Rezarf]

I'm running around 13 degrees as well. But I did swap out an electronic ignition from a 60 series... now that made a difference!

 

[PabloCruise]

If you have a combination distributor (one with vac adv. and vac retard) disconnect the retard side and put a vented cap on it (to let it breathe as needed, but keep dirt out). Then adjust the base timing ahead some until it's either hard to start the engine, or knocks - and then back it off.

I'm sure others have some other ideas here - so chime in.

Steve

2 Questions (and they may seem silly)

1) Why does the engine become hard to start with too much advance?

2) Does exhaust become stinkier with more advance?

I cranked up the timing on the 3FE Pig and she runs strong! No knocking, but sometimes when starting it falters like the starter is intermittant or bad. It also seems like it is a little stinkier than before when the timing was less advanced. There is no cat on this Pig, but the timing may not be my only variable. When I had a clogged fuel return line it was fattening up my fuel pressure in the rail and making it run stinky. I have installed a transparent filter between the tank and the inline pump and I can see a good flow, so I do not think I am clogged now.

Thanks for fielding my questions!

 

[SteveH]

a) too much advance = harder to start because it's firing *before* TDC - causing the engine try to push the cylinder down before it has reached it's apex/zenith (TDC). A little of this is ok, which is why most engines run timing advanced from TDC. Too much of this causes this 'firing too soon' problem and hard starting.

b) general answer: engines run efficiently between certain parameters of timing and fuel, and having the timing far advanced presumably causes incomplete combustion or the higher emission of some component that stinks more. Generally, for emission tests, you want to retard your timing, if you have it far advanced for performance reasons. This will help with HC. Dialing the distributor advance back a bit and upping the idle speed are the classic 'parking lot move' before you drive into the emission station.

 

[theRash]

b) general answer: engines run efficiently between certain parameters of timing and fuel, and having the timing far advanced presumably causes incomplete combustion or the higher emission of some component that stinks more. Generally, for emission tests, you want to retard your timing, if you have it far advanced for performance reasons. This will help with HC. Dialing the distributor advance back a bit and upping the idle speed are the classic 'parking lot move' before you drive into the emission station.

I will be taking my 40 to get emissions as soon as I get a muffler for it. I have my timing advances to 16 degrees. Is is better for me to retard it to the standard 11-13 range for the the purpose of emissions? I will be giving it a valve adjustment before then too. I want to give it the best opportunity to pass emissions. What is the optimal retard/advance setting for passing emissions? Plus if I retard the timing, do I need to reset anything to the carb?

 

[PabloCruise]

I will be taking my 40 to get emissions as soon as I get a muffler for it. I have my timing advances to 16 degrees. Is is better for me to retard it to the standard 11-13 range for the the purpose of emissions? I will be giving it a valve adjustment before then too. I want to give it the best opportunity to pass emissions. What is the optimal retard/advance setting for passing emissions? Plus if I retard the timing, do I need to reset anything to the carb?

I am just guessing here, but I have heard a rule of thumb is to take the 7 degrees BTDC that Toyota specifies and then add 1 degree for each 1000 ft of altitude. So for us, 7 + 5 = 12 degrees BTDC. I would try that (tell me if your exhaust smells any better!) and set your idle a little higher. I am not sure what the max idle RPM they set for emissions testing in Denver, but a little higher idle won't hurt you. If you wanted to bust out the vacuum gauge and set idle mix for max vacuum, I think that will give you the most efficient burn.

Please feel free to correct me if I am being a fool!

Credit to Hulk: http://www.risingsun4x4club.org/forum2/showthread.php?p=50184#post50184

 

[PabloCruise]

a) too much advance = harder to start because it's firing *before* TDC - causing the engine try to push the cylinder down before it has reached it's apex/zenith (TDC). A little of this is ok, which is why most engines run timing advanced from TDC. Too much of this causes this 'firing too soon' problem and hard starting.

b) general answer: engines run efficiently between certain parameters of timing and fuel, and having the timing far advanced presumably causes incomplete combustion or the higher emission of some component that stinks more. Generally, for emission tests, you want to retard your timing, if you have it far advanced for performance reasons. This will help with HC. Dialing the distributor advance back a bit and upping the idle speed are the classic 'parking lot move' before you drive into the emission station.

Do you think idle timing can effect the combustion process enough to discern with the human nose?

Hmm... I wonder if we can train beagles to indicate when we have the perfect 14.7:1 air fuel ratio!!!

 

[theRash]

I am just guessing here, but I have heard a rule of thumb is to take the 7 degrees BTDC that Toyota specifies and then add 1 degree for each 1000 ft of altitude. So for us, 7 + 5 = 12 degrees BTDC. I would try that (tell me if your exhaust smells any better!) and set your idle a little higher. I am not sure what the max idle RPM they set for emissions testing in Denver, but a little higher idle won't hurt you. If you wanted to bust out the vacuum gauge and set idle mix for max vacuum, I think that will give you the most efficient burn.

I'll lower it to the 12-13 degree range. Can't say my nose is that tuned in for the change in the smell of exhaust. I'd love to try to dial in teh idle mix using the vacuum gauges.. Which vac hose is the best to use?

sorry for still prying, but I would like to only go to the emissions place once... and only once...

 

[PabloCruise]

I was hoping someone else would have chimed in on this, but my recomendation would be to go for any source of manifold vacuum (vs. ported vacuum) i.e. a steady vacuum signal downstream of the throttle. Set your RPM up first, again check the max RPM for your idle test and go a little below that. Then adjust idle mix for optimal vacuum signal.

Help yourself for the emissions test - change your oil and plugs right before you test.

 

[ttubb]

Help yourself for the emissions test - change your oil and plugs right before you test.

One other thing I have heard done is to run your fuel tank down and then use E85 just prior to the test. No first-hand experience on this, but I hear it helps. Terry

 

[RicardoJM]

HEET is similar to the E85. If you do not pass, you get a retest for free. If you don't pass the first go around - I would recommend biting the bullet and having a shop dial you in.

When I did the emissions on my 71 and failed, I tried to make adjustments for my retest and still failed. In retrospect, after the initial failure I would have been better off if I had gone straight to a shop to get my rig dialed in. IIRC it was a couple of hours labor and around $100 for the work.

I live on the south end and can recommend Colorado Car Clinic on South Broadway. He has the same equipment that is used at the emissions testing place and is able to make adjustments then check them out on his equipment.

 

[treerootCO]

#1 rule in Colorado emissions.....buy or borrow a new gas cap. Guaranteed to fail you the first round.

#2 get the rig out on the highway, drive 50+ miles and then go to the testing center

#3 tune up

#4 HEET in the tank, red not yellow bottle. High octane will help too.

#5 Dig deep into the beast, jet or rebuild carb, lash valves, valve regrind and seals...

#6 ???

#7 Huge proffit?

 

[theRash]

Thanks for the tips. Getting my muffler first. Then taking several of these tips and heading to the emissions place sometime between now and Oct 12th when my temp tag expires.