I feel so needy... Engine interference after timing belt change

[squealingtires]

1974 Fiat 124 1800cc that I've been trying to help my dad get going after a restfull 20yrs in storage. I got it running but I wanted to do a tuneup. I recently changed the timing belt on this motor and followed all of the directions both in the manual and with others help from this site. The engine was missing the timing belt cover so I found a plastic cover on Fleabay and this cover required me to swap the smog exhaust gear wheel out for which I verified that the new dowel pin and referenced holes aligned to the old gear. Then I use a dial indicator on piston 4 to establish TDC the then used the markers on the cam housings and gears to line up the camshafts. Checking the distributor the rotor is pointing the cylinder 4 so everything checks out for the valvetrain. For the aux shaft, I clocked the gear to align the reference hole to the tensioner spring bolt at about 35 degrees or so from the top. Then I put the new belt on and turned the motor over several times and then tighten the tensioner up. I put everything else back together and turn the motor over by hand several more times and everything check out including all the timing marks. With the plugs out I then engage the starter to freespin the motor and I hear a slight tick but I figured this was the distributor making noise. So without any major clanking/banging I figured I was safe to install the plugs and see if she'd fire up. Well she fired up but was making a racket so I shut it off about 2 seconds later. What in the world is this noise? So then I pulled the plugs and tried to turn the engine over by hand but the crankshaft pulley's reference mark stops at the 8 o'clock position when turning it forwards and backwards. So thinking that I had just blown up my dad's car I began undoing my belt installation. With the crankshaft in the "locked-up" position and without the belts on, I'm able to turn both the cams over without any interference. I was told this is a non-interference engine so this is what I expected. Then I move on to the aux shaft gear and again with the crank in the "locked-up" position I'm able to spin the aux shaft around with out and interference. Then I pop off the cam covers just to make sure everything looked ok and I observed the cam followers moving as they should. What could be my problem? Have I destroyed something and what should be my next steps? I'm not an expert and I know very little about these cars. Thank you for the help.

[vandor]

Almost sounds like a nut fell into the carburetor and is now lodged in piston 2 or 3, which are at TDC when the timing mark is at 8 0'clock position.

BTW, the 1800 IS an interference engine, both piston to valve and auxiliary shaft lobe to the #2 conrod.

[76was124]

Almost sounds like a nut fell into the carburetor and is now lodged in piston 2 or 3, which are at TDC when the timing mark is at 8 0'clock position.

Or maybe through one of the spark plug holes. Were the plugs in tact (not broken off) when they came out?

@Csaba, how much clearance is there above the piston at TDC? Just wondering how big a part (Nut) would it take to cause interference vs just noise?

[bradartigue]

Get a small magnetic tool and pull the plugs, stick it in the cylinder bores and go fishing

[131]

@Csaba, how much clearance is there above the piston at TDC? Just wondering how big a part (Nut) would it take to cause interference vs just noise?

Not uncommon for the studs in the top of the carb that hold the air cleaner on to be stripped out of the alloy and get ingested. Anything bigger than 1-2mm can jam things up.

[ORFORD2004]

Get a small magnetic tool and pull the plugs, stick it in the cylinder bores and go fishing

I hope he will be more lucky than me. It happen twice to me but with a stainless steel nut. It end up with a snake camera with a hook at the end.

[vandor]

> how much clearance is there above the piston at TDC? Just wondering how big a part (Nut) would it take to cause interference vs just noise?

There is space in the middle, but only 1-2 mm on the sides where the squish areas are, so a not or bolt would be hammered into the head or the piston.

[squealingtires]

Well the good news is that I found the problem. Can you figure out which part of my dial indicator decided to leap to its death down cylinder #2. The bad news is that the aluminum thumb-screw (2 o'clock in the dial) did some damage to both the piston and the cylinder head in the couple of seconds that the engine was running. The unfortunate news is this could have all been prevented if I had done a better job makings sure my tools weren't falling apart and keeping the engine holes plugged. So what do you think of the damage? Do you think the damage could be more than what we're seeing (e.g. bent rod/piston pin, damaged bearing, cracked head, etc). Or do you think I got lucky and the damage can be smoothed out and the engine put back together. What would you all do going forward? Again, thanks for the insights.

[bradartigue]

The sad truth is you've got a bad head now...however, if this is the only damage and it does not extend into the head gasket ring then I'd get a new gasket and run with it. I've seen worse on running cars...

[vandor]

Just smooth it out so there are no sharp edges and run it.

[azruss]

It looks like 3 stress cracks coming from the damage. check those out thoroughly before continuing.

[djape1977]

that engine burns oil

do a leakdown test