Carb spitting up

[architect]

Hi everyone,

I’m having a few issues keeping my 78’ 124 at idle. It’s been a while since she’s ran, but has a fresh tune up and lots of work.

High level modification
- new Weber 32/36 DFEV w/electric choke
- all smog removed
- new computeonix ignition and sparks
- all fuel components new (tank, electric pump, lines , fuel pressure reg, sender, etc)
- new starter
- all new cooling and alum radiator

The car ran idle great the mods above, but for some reason.. it’s not running at all, and I’m not able to set the timing with my digital gun

I have a suspicion it my be too much fuel pressure. At the moment it set to 3 PSI.


What happens... crank the car after sitting for a while, hesitates to fire up but will... runs for 10 seconds and stalls.

If I attempted again, with the filtered off, it will spit fuel / cloud/ mist out the carb.

Any suggestions.. I’m sure I did something since the last time.. and want to be careful.

Timing belt looks fine..

[architect]

[architect]

Oh and I’m doing this while the car is dry! Just wanted to share pics for fun

[18Fiatsandcounting]

It's hard for me to say with the modifications you have, but my first suggestion would be to verify the cam and ignition timing. I've occasionally gotten these way out of whack, with the result that carburetor spits and otherwise complains.

Cam timing can be fairly easily verified by making sure that two index holes in the cam pulleys are both pointing towards the metal bracket "pointer" bolted to the top of the thermostat housing (assuming you have the bracket pointer installed). On all the 124 engines that I've had, this point in the engine rotation cycle is now where cylinder #4 (rearmost) should be firing, and so I verify that the distributor rotor is indeed generally pointing towards the contact on the distributor cap for the #4 spark plug wire. Since you've got electronic ignition, this suggestion may not help in your case.

I once had a MG Midget engine that I did some extensive work on, and it did start but ran poorly. My first clue was when I put it into reverse to back it out of the garage and the car moved forward upon releasing the clutch. Apparently, I had found the right combination of timing and such that allowed the engine to run backwards (sort of). I'm still not sure how this was possible, but it's hard to argue with a car that moves forward when put in reverse...

Anyway, to get back to your issue, try verifying the timing and see where that gets you.

-Bryan

[architect]

Thanks for the advice on cam timing. I checked it out, looks really close... exhaust and intake on the marks, crank and aux aligned. Is there any other way to verify?


Update: lowering the fuel to 2psi made a big difference. She was able to idle really nice..

The engine starts up smoothly, and will idle fine, rev up to 4K real easy...

Problem is when I turn it off, if I immediately try to restart, I get the same results. If I let the car rest for 20 mins, fires right up.

Also, I did get to a point where I can get the digital gun out and attempt to use this tool for the first time (personally ever). I placed the clip on plug wire one, pointed to the pulley and rev to about 3200 rpm.. looks pretty solid. The computronix manual says the the following:

“A variable or dial back timing light can not be used unless the delay is set to zero and it’s is used as a conventional timing light”

“Typical timing is 33 to 35 degrees BTDC at maximum advanced. The engine should be running at 3000 to 3200 to check max advanced.”

How do I check this with the digital gun? Other than pointing at the crank pulley.. do I need to mess with the gun advanced settings or leave at zero?

Sorry, I’m newbie.

[18Fiatsandcounting]

It sounds like your cam and aux shaft timing is good. Is the engine perhaps flooding when you turn it off? Try idling for a few minutes with the air cleaner removed and (with a flashlight) carefully look down the venturis of the carburetor. There should not be visible fuel flowing out of the nozzle in the middle (the secondary venturi). Another trick is to try depressing the accelerator pedal all the way to the floor when starting (hold it there; don't pump it) and see if it starts and runs any differently. If fuel is pooling up in the intake manifold, depressing the accelerator and holding it there when started helps to clear out the excess fuel.

I also have one of those timing lights where you can dial back the triggering of the flash with a knob on the back, but I personally don't trust this and I just set the knob to zero and use it like an ordinary timing light. I have earlier Fiats which like to be around 10 degrees BTDC on idle, and about 35 to 40 degrees BTDC when fully advanced (above 3000 rpm if I recall). Since the timing marks are notoriously difficult to read accurately, and generally only read 0 to 10 degrees BTDC, I generally just try to get in the ballpark and then adjust the timing in a few degree increments until the car seems to run best under all conditions. Sometimes this takes adjusting, going down the street for a drive, readjusting, repeat until it feels right.

I'm not sure I've helped, but those are my thoughts.

-Bryan

[architect]

Thanks for the advice Bryan, I will check out the carb later down the week.

I’m really don’t think the distributor(less) timing is effecting the carb spitting.. it’s either a flooding or my intake cam timing is off?

Next step, I might dial the pressure back a little more and check the throttle cable tension.. it maybe opening up the carb while the pedal is at rest!

[SteinOnkel]

What components are in your fuel delivery system?

Most, but not all, adjustable fuel pressure regulators for carbs and complete and total junk.

[18Fiatsandcounting]

Let me know what you find out. It's been years (decades) since I worked on a Fiat engine that was spitting, and I vaguely recall it was an issue with either ignition timing that was way out of whack, or cam timing as you note. I also recall that a mixture that is way off in terms of too lean or too rich can cause issues.

Also going by memory here, but the causes of the spitting I was seeing where when the engine tried to start but then was "kicked back" in the reverse direction once it fired, thus sending fuel spraying back out of the carburetor, since at least one intake valve was open and the engine was now pumping out rather than pulling through the carb. However, that doesn't sound like your issue.

I think you already checked the intake cam timing, but to restate, make sure the engine is at TDC (cylinders 1 and 4), verify that the two cam index holes are pointed towards the index pointer, make sure the aux. cam index hole or mark is something like 35 degrees past "noon" in the clockwise direction (I'm going by memory on that one, so don't hold me to that), and you should be good. See: https://www.youtube.com/watch?v=rHWn50AFe5g

-Bryan

[architect]

What components are in your fuel delivery system?

Most, but not all, adjustable fuel pressure regulators for carbs and complete and total junk.

- Edelbrock FRP - ranges from 1-4 PSI and a gauge on my dash, between the FRP and carb inlet. Clean filter, just checked
- 5/8 braided supply and return lines
- Facet fuel pump
- tank and sending unit from Autoricambi
- tank vent hoses hooked to valve / breather

[architect]

Here’s a short video of the symptoms.. after the car sits for 20 mins or so, it fires up perfectly fine.. on the second or so crank.

FYI: I upgraded to Vicks starter.. it sat in a box for almost 2 years before getting around to it. Pretty slick!

https://www.dropbox.com/s/rmzki3uowj063 ... M.mov?dl=0

[architect]

Let me know what you find out. It's been years (decades) since I worked on a Fiat engine that was spitting, and I vaguely recall it was an issue with either ignition timing that was way out of whack, or cam timing as you note. I also recall that a mixture that is way off in terms of too lean or too rich can cause issues.

Also going by memory here, but the causes of the spitting I was seeing where when the engine tried to start but then was "kicked back" in the reverse direction once it fired, thus sending fuel spraying back out of the carburetor, since at least one intake valve was open and the engine was now pumping out rather than pulling through the carb. However, that doesn't sound like your issue.

I think you already checked the intake cam timing, but to restate, make sure the engine is at TDC (cylinders 1 and 4), verify that the two cam index holes are pointed towards the index pointer, make sure the aux. cam index hole or mark is something like 35 degrees past "noon" in the clockwise direction (I'm going by memory on that one, so don't hold me to that), and you should be good. See: https://www.youtube.com/watch?v=rHWn50AFe5g

-Bryan

Bryan,

First this I'll get to (next few days) will be.. taking a paper template, make sure the crank is position exactly with Aux. Remove plug 1 and 4 to ensure TDC, and verify cam timing.

Will one tooth being off effect this? The pointers on the cam towers are very close, within 1/8" of the pulleys (I have Vicks non-adjustable).

I will take picture of the carb, curious if I'm missing any vacuum port caps, or capped of something I wasn't supposed to. The electric choke works good.

Ugh! So much work.. just want to cruise!

[geospider]

If all of your marks line up, the cam timing should then be good. If recently replaced dizzy, line all marks up and check that rotor is at #4.
My first thought was your float adjustment is off. If new carb out of the box, they always need adjustment. I had this problem: 1st too high and pouring fuel into motor enough to be in the oil. then of course I set too low and it chugged when pushing it. Take you time and set the float adjustment.

Geo

[18Fiatsandcounting]

I doubt that the cam timing being off by one tooth would cause your problem, either exhaust or intake cams or both. In fact, in my younger (more foolish) days, I played with the cam timing one tooth in either direction to see if I could extract any more performance out of 1438 cc. Short answer: No.

If your timing belt has even a little bit of play in it, you could be off by 1/8" or so on the cam timing marks. With the cam timing marks lined up and transmission in neutral, see if you can rotate the crankshaft at all by hand. If so, you may need to release the lockdown nuts on the timing belt tensioner pulley and make sure it's pulling the belt taut. Retighten after correcting, of course.

If a lot of hoses have been removed or capped off in the intake system, that could be affecting your air/fuel mixture which could lead to some issues. Let us know through pictures or descriptions what you have going on here.

-Bryan

[architect]

If all of your marks line up, the cam timing should then be good. If recently replaced dizzy, line all marks up and check that rotor is at #4.
My first thought was your float adjustment is off. If new carb out of the box, they always need adjustment. I had this problem: 1st too high and pouring fuel into motor enough to be in the oil. then of course I set too low and it chugged when pushing it. Take you time and set the float adjustment.

Geo

Will you elaborate adjusting the float please?