76 Spider first time cranking: issues

[Rob123]

I’m new to this site and new to Fiats, I’ve valued the info I got in this site so far.

I picked up a project car and after sorting some things out, I’m now trying to get it to idle. When I crank it I get episodes of the engine idling roughly for 1 to 5 seconds and occasional backfire thru the carb. More specifically it’s a burst of misty pressure. On some occasions: flames.

I’ve checked timing marks, pulled valve covers and verified cam lobes and did the stick test to verify crank TDC. I’ve checked ignition timing with a timing light on all 4 cyclinders (one at a time, making sure it always flashes at the same crank position every time). I have ~120 psi on all 4 cylinders. I have NOT yet gone over the carb but it is spraying fuel and I get same results when squirting in starting fluid.

Any other ideas of what to check??? Occasional flames must mean a spark plug figure when an intake valve is open, right?

I ultimately want to go Megasquirt and spark but wanted the engine to at least idle before converting as I don’t know the history on the car yet.

[18Fiatsandcounting]

Sounds like the ignition timing is off. With the crankshaft at TDC and the little holes in the camshaft pulleys lined up with the pointers (or with the nubs on the very front of the cam housing), the distributor should be set to fire on the #4 spark plug. Not the #1. Occasionally I have seen engines set to the #1 plug, but the engine runs very poorly. If at all.

-Bryan

[Nut124]

What is the observed ignition timing?

Those symptoms could be caused by:
- Cam timing way off or a very hot, unsuitable intake cam
- Ignition timing off
- Bent intake valve. Unlikely since your cranking compressions are uniform.

[Rob123]

Thanks for the replies.
Weird thing: previous owner wired the spark plug wires backward (as if 4 was on radiator side) so I rewired last week and the performance got a little better, but still won’t consistently idle and getting backfire thru the carb. I did just pull the distributor and with all the timing marks aligned, the rotor points to cyl #4. Looking at the cams, cyl #4 has both valves closed with exhaust cam sticking straight up.

I’m fairly certain the cam is stock.

I was thinking the same about intake valves sealing as I’m getting OK compression.

Could the cylinders be flooded with fuel or oil??

[Nut124]

You can set the engine to time on #1 or #4 but not without adjusting the timing by turning the dizzy or by rearrainging the plug wires.

Set it to fire at #4 at the marks. Set idle timing at 10-15 BTDC. If it does not idle w/o spitting, then something is wrong.

What was the idle ignition timing you observed?

[Rob123]

I was moving the dizzy back and forth but settled around 5 degrees BTDC
I’ll try 10-15 BTDC at cranking speed

[Rob123]

Tonight I messed with the timing a bit and sprayed starting fluid into the Weber 32 carb port with the extra butterfly valve… I can steadily keep the engine running if I keep spraying starter fluid in!
So, I have a fuel delivery issue.
Now time to figure out what all these ports, hoses and screws do on this carb… I never worked on a carb before, so I’m tempted to Megasquirt it.

[18Fiatsandcounting]

Tonight I messed with the timing a bit and sprayed starting fluid into the Weber 32 carb port with the extra butterfly valve… I can steadily keep the engine running if I keep spraying starter fluid in!
So, I have a fuel delivery issue.

I agree that it now sounds like a fuel delivery issue. Your note about the "extra butterfly valve" caught my eye. I think you might be referring to the automatic choke plate for the primary barrel of the carburetor. If memory serves, your '76 should have a 32ADFA carburetor which has a choke plate only on the primary barrel.

Is this choke plate open or closed when you start the car, with the engine cold? If it is open, then you may simply have an automatic choke that isn't working right, and that will make it hard to start and keep running with a cold engine.

By the way, the Weber 32ADFA setup is quite good when everything's working as it should, but by 1976, Fiat engines did have a lot of plumbing. Don't start pulling off vacuum hoses until you know specifically what they do, as this usually makes the engine run worse. The engine was designed to work with everything in place and working, so if you remove something, oftentimes you have to compensate somewhere else.

-Bryan

[Rob123]

Thanks Bryan.
You’re correct, it’s the choke on the primary barrel.
I’ve been adjusting the mixture screw and idle speed screw and got to a point that the car will occasionally idle with gas from the tank (no staring fluid).
You’re also right that it’s a 32AFDA, I’ll look into setting up this carb properly. It’s been consistent that everything the previous owner did was wrong… all vacuum lines have been disconnected.