Technical Ignition - I know.. this again!

[dangfiat]

Hi All,

A little story about my continuing adventures. Apologies for the length, and I know this ignition thing has been done to death but I have questions.....

My little Fiat (with a 650cc) has stopped running: won't start or even try to catch.
1. I replaced the points (gapped to .48mm), & the condensor. Had to pull the distributer to do it.
2. I got the motor to the TDC mark, put the dizzy in with the rotor pointing straight at the block. Rotated to the 10degree mark, spun the dizzy so a test light showed the points
3. Pull the starter switch.... no fireing, not even a catch
4. I think "what if I'm on the wrong TDC?"..... So I switch the plug leads at the distributor cap (switch 1 & 2 around)
5. Fired right up! YAY!!....... Wouldn't rev (would die with anything but gentle throttle) and made backfire noises. Drove up the street and the engine just died, cut out. No starting. NO JOY, I was a sad sad Dan (also a tired Dan... even this little car is annoying to push for a block or two )
6. So... I've replaced the condensor (again) and flipped the distributor around, retimed it. Nothing, no start, no nothing. Won't start

I'm off to replace the coil next. Darn thing is waaaaay back in the left side of the engine bay. Should be exciting getting in there!

Question (Finally!!!): How do you tell what cylinder is at TDC when on the timing mark? I assume the rearmost cylinder is #1?

Thanks everybody, I'll get this little dragon back to breathing fire yet!

Daniel

 

[Goldnrust]

Sorry that it’s still fighting you!

If you had it running a bit at stage 5 of your journey, then I’d say go back to that point and maybe try advancing or retarding the distributer a bit from there.

Not meaning to be patronising, but when using a test light, you are setting it so the light goes out as you pass the 10 degree BTDC mark when rotating the engine in the normal direction, yes?

Have you got a timing light / strobe to hand? That might help you diagnose what’s going on if it’s timing related.

If you remove the rocker cover you can see the valves moving. As you approach TDC, one cylinder will have both valves firmly closed, and one will have the exhaust closing as you approach TDC and the intake just starting to open as you pass TDC. The cylinder with the valves firmly closed is the one on the firing stroke.

Most engines as labeled with cylinder 1 furthest from the flywheel, near the ‘front’ of the engine, in this case the back of the car (confused yet? I am! Haha). I believe the 500cc engines are labeled this way, with cylinder 1 furthest from the flywheel… but I’m sure I read on the forums that 650cc engines are labeled the other way round with cylinder 1 nearest the flywheel. I’m sure one of the other more experienced guys can confirm.

 

[dangfiat]

@Goldnrust Thanks for the reply!

For the test light: I'm setting it to just turn ON at the 10deg BTDC (meaning this is when the points open)? Am I doing this backwards? Will have to research this

For the timing gun: Where do you attach it? The battery is up in the front and I don't have leads long enough

Thanks for the input

Daniel

 

[Goldnrust]

I fear you are doing it backwards (though as this could be an easy fix maybe it’s not bad news!).

As the engine rotates the point first need to close (completing the circuit and the test light will come on) and start to charge the coil, then it is at the point when the points open, breaking the circuit (and the test light will go out) that the magnetic field that has been charged up inside the coil will collapse triggering the spark.

So you are looking for the light to go out at 10 degrees BTDC as you rotate the engine in the running direction.

For a timing light, you should be able to pick up +12v from the coil, or from the dynamo, and Earth to anywhere on the engine block.

 

[fiat500]

Se

@Goldnrust Thanks for the reply!

For the test light: I'm setting it to just turn ON at the 10deg BTDC (meaning this is when the points open)? Am I doing this backwards? Will have to research this

For the timing gun: Where do you attach it? The battery is up in the front and I don't have leads long enough

Thanks for the input

Daniel

Set the raised timing mark on the pulley until it aligns with the 10 degrees mark or a mark made 13mm before the main or only raised timing mark on the casing. More commonly, measure 13mm clockwise from the pulley timing mark and make a new mark on the pulley. Then turn the engine clockwise until that new mark aligns with the original, main mark on the cover.
Get your points gap perfect. Loosen the distributor enough to be able to turn it. Assuming that you have fitted it correctly, turn it slightly anti-clockwise until the points are closed. Connect your test-lamp or meter. Slowly turn the distributor clockwise until the light just goes off or voltage drops to zero.
The engine is now statically timed.

 

[myoshik]

The cylinder numbering confused me too...on my 126A it turns out 1 is by the fly wheel. As Goldnrust mentioned, look at the valves while turning the engine to be 100% sure.

Also, as an optional last step - after completing everything pointed out above, I ignore the timing mark and turn the engine over once to where the points are just about to open. Then I look at the timing mark to make sure the marks are correct.

 

[dangfiat]

So... success, to a point. Thanks all for getting me this far!!

I've got the car fired, but it does the following:
1. On the choke -- it pops/backfires and when I push the throttle it dies. (see attached video)
2. Off choke it sounds fine, but still hesitates pretty badly when I punch the throttle.
3. If I completely remove the air filter and just run the open carb: It runs much, much better. Still hesitates sometimes, especially if I suddenly floor it. But overall much better (could even drive around the neighbor hood)

So now: some questions!
1. Does the spitting/hesitating on choke & with the filter say it's running really rich normally? And giving it extra air leans it out some?
2. Can a slightly off timing cause hesitating?
3. The only thing I haven't replaced is the coil & voltage regulator. Might just do that to be on the safe side

Finally, I've bought a carb rebuild kit but not the float (should probably get one of those just in case). I'll rebuild it over the weekend and see what happens

Thanks again all, having fun with the car but it's time to get on the road!

Cheers
Daniel

 

[myoshik]

I'm not sure if I can be much help, but from my own limited experience:

Sounds like it may be fowled jets and/or passages...not sure, but it doesn't appear like you need a new float (unless you feel like the engine is using way too much fuel). I read a post an easy way to tell if the float has a hole in it is to simply shake it to see if you can "feel/hear" fuel sloshing inside it. I'm guessing once you rebuild it, it'll solve some of these issues.

Were you able to verify the timing with a timing light? Can you get a smooth idle by adjusting the mixture/throttle stop screws? My engine ran similarly to yours, but after timing was sorted out it ran and sounded so much smoother (I eventually found that I needed to replace the timing chain...the chain was so loose that it damaged the main bearing. On a side note, I also needed to have the rocker arms fixed as they got to the point where I could not set the clearance properly which contributed to my timing issues).

 

[Toshi 975]

Hairline cracks in the carb float are almost impossible to spot by eye. I test the float by filling a mug with boiling water then pushing the float below the surface. If you get a stream of bubbles you know you have a split. It is possible to soft solder over the split as a temporary repair.

 

[the hobbler]

Hairline cracks in the carb float are almost impossible to spot by eye. I test the float by filling a mug with boiling water then pushing the float below the surface. If you get a stream of bubbles you know you have a split. It is possible to soft solder over the split as a temporary repair.

Sadly, modern "E" fuel loves digesting parts of the classic car fuel system--including the solder on brass floats. Toshi's method to check the float is one way, another way is to simply shake the float--you will hear if there is fuel in it, and new floats are not very expensive. In most of the UK, according to their web-site, ESSO 99+ fuel has no ethanol (and only 5% in parts of the West Country and Wales), so I always advocate using that fuel wherever possible---are you able to obtain low/zero Ethanol fuel in the US of A? If you can, use that and also an "Ethanol-proof" additive as a 'belts and braces' move.

 

[myoshik]

E10 is the most common here and it did damage my car...I was using it with something I got at a hardware store called "STA-BIL 360 Ethanol Treatment" so I'm not sure if it was the E10 or the treatment that did the damage (also very possible I didn't use it correctly). In parts of the USA I've even seen stores sell E15! Thankfully, there's a store near by me that sells E0...so that's all I put in my 500 and it's been trouble free. Unfortunately it's quite expense here, sometimes double the cost of E10; for those in the USA, this website is helpful, but occasionally not accurate so its best to call ahead:

Pure-gas.org - ethanol-free gasoline in the U.S. and Canada

Pure-gas.org is the definitive web site listing stations that sell pure gasoline in the U.S. and Canada.

www.pure-gas.org

Also for those in the USA, I've seen NAPA Auto Parts occasionally sell E0 in various sizes, so it worth checking if there's one near by. Hope this helps!

 

[Bounding Bambino]

E10 is the most common here and it did damage my car...I was using it with something I got at a hardware store called "STA-BIL 360 Ethanol Treatment" so I'm not sure if it was the E10 or the treatment that did the damage (also very possible I didn't use it correctly). In parts of the USA I've even seen stores sell E15! Thankfully, there's a store near by me that sells E0...so that's all I put in my 500 and it's been trouble free. Unfortunately it's quite expense here, sometimes double the cost of E10; for those in the USA, this website is helpful, but occasionally not accurate so its best to call ahead:

Pure-gas.org - ethanol-free gasoline in the U.S. and Canada

Pure-gas.org is the definitive web site listing stations that sell pure gasoline in the U.S. and Canada.

www.pure-gas.org

Also for those in the USA, I've seen NAPA Auto Parts occasionally sell E0 in various sizes, so it worth checking if there's one near by. Hope this helps!

It is most definitely the ethanol that caused the damage. Ethanol is hygroscopic and absorbs moisture. When it does, it becomes highly corrosive and causes significant damage to metal components. especially inside float bowls and fuel systems. Stabil is one of the best products to help prolong fuel life and prevent this corrosion from happening. It doesn't hurt to use too much stabil. But keep in mind, that ethanol based fuels have an extremely short shelf life compared to fuels of the past. And one thing folks forget to do after adding stabil to their vehicles/yard equipment before winter storage is to run the engine so the treated fuel can flow thru the entire fuel system.

Ive been using it for years, and its the only thing thats been giving temporary use equipment a fighting chance.

Ethanol in fuel has caused insane amounts of damage and issues in many aspects especially in the marine industry. If you are constanly running fresh ethanol fuel thru your system frequently you shouldnt see any issues, its when it sits and has time to turn acidic is when the damage starts.

 

[dangfiat]

So.... Continuing adventures

Got the car started (it starts pretty easily), let it warm up. Shot it with a timing gun, was about 20deg BTDC!

Rotated the dizzy back to get to 10deg BTDC (measured both with the timing marks on the timing cover and with an "advance timing gun"

Still hesitates like crazy on throttle... DANGIT!!!.... Well, at least I know the ignition system is working well.

No amount of playing with the mixture screw yields a satisfactory result... With or without the air filter

QUESTION: The idle mixture screw spins rather freely, is that normal?

NEXT STEPS:

1. The previous owner glued the rocker cover down, so will need to buy a gasket. The guy was a total hack (not saying I'm a talented mechanic, but I try to do things right)
2. I'll pull the rocker cover and carb. Clean/replace what I can on the carb (main, idle, float needle, mixture screw - came in a kit).
3. Set rocker clearances (it's .002" cold for a 126P engine? If someone in the know knows.....)
4. Pull the cord and see what happens, there's only 2 outcomes:
   1. It works, and I drive the Fiat to the store for a celebratory wine!
   2. No joy, and I drive the daily car to the store for a consolation beer while I contemplate the meaning of life (or Fiats..... )

Thanks all again for following along on my journey. Very much appreciate this forum!

Daniel

 

[the hobbler]

So.... Continuing adventures

Got the car started (it starts pretty easily), let it warm up. Shot it with a timing gun, was about 20deg BTDC!

Rotated the dizzy back to get to 10deg BTDC (measured both with the timing marks on the timing cover and with an "advance timing gun"

Still hesitates like crazy on throttle... DANGIT!!!.... Well, at least I know the ignition system is working well.

No amount of playing with the mixture screw yields a satisfactory result... With or without the air filter

QUESTION: The idle mixture screw spins rather freely, is that normal?

NEXT STEPS:

1. The previous owner glued the rocker cover down, so will need to buy a gasket. The guy was a total hack (not saying I'm a talented mechanic, but I try to do things right)
2. I'll pull the rocker cover and carb. Clean/replace what I can on the carb (main, idle, float needle, mixture screw - came in a kit).
3. Set rocker clearances (it's .002" cold for a 126P engine? If someone in the know knows.....)
4. Pull the cord and see what happens, there's only 2 outcomes:
   1. It works, and I drive the Fiat to the store for a celebratory wine!
   2. No joy, and I drive the daily car to the store for a consolation beer while I contemplate the meaning of life (or Fiats..... )

Thanks all again for following along on my journey. Very much appreciate this forum!

Daniel

I think that you will find that the valve clearances are 0.2 for the inlet and 0.25 for the exhaust--COLD

 

[dangfiat]

I think that you will find that the valve clearances are 0.2 for the inlet and 0.25 for the exhaust--COLD

Thanks! Waiting for the rain to subside here so I can get out there and give it another go. My Riley is currently occupying the garage with a 1275 (from 998) upgrade