Technical 1978 124 Project

[124BC1]

Re:- Broken stud removal.
I'm a great believer of using penetrating fluid (you choice) and giving it plenty of time to work.

I'd position the cyl. head with the broken stud vertically, remove the stud and apply penetrating oil. I might gently heat the head surrounding the broken stud and then apply the penetrating oil, the sudden cooling may draw in the penetrating fluid better.
Chances are that the broken portion of the stud is bottomed out in the threaded hole.
It's important to start drilling at the exact centre of the stud - if below the surface, given that the cyl. head is al. alloy, I might try refitting the exhaust manifold to try to guide the drill bit. Or I might drill a hole is a piece of steel plate, align this hole with the exact centre of the broken stud, clamp the plate to the cyl. head and use it as a guide for drilling the stud centre.
There are stud extractor sets that include guide bushes for the drilling process. I prefer to use a spline type of extractor rather than the tapered screw type. E.g. :-

In my early days (with very few tools and even less money) I used to drill 2 holes, a small one the full of the broken piece of stud and a larger hole halfway in, then tap the tapered square tang of a file in and use this to wind out the broken stud - if done gently, this often worked but if the tang of the file broke off in the broken, stuck, stud...

An even easier way of removing studs broken off below the surface is not to use any penetrating oil, just use an arc welder to stick a flux-coated rod to the broken stud, disconnect the rod holder, allow the heat to spread into the head and then try using the welding rod to wind the stud out.

This is also how a broken head bolt can be removed in situ without having to remove the cylinder head...
And if a cyl. head bolt were to break, the broken threaded piece (the fracture point will usually occur in the threads that were not engaged with the threads in the cyl. block) will not be tight so should be easy to unscrew and remove. So, no big deal.

 

[smahaley]

Re:- Broken stud removal.
I'm a great believer of using penetrating fluid (you choice) and giving it plenty of time to work.

I'd position the cyl. head with the broken stud vertically, remove the stud and apply penetrating oil. I might gently heat the head surrounding the broken stud and then apply the penetrating oil, the sudden cooling may draw in the penetrating fluid better.
Chances are that the broken portion of the stud is bottomed out in the threaded hole.
It's important to start drilling at the exact centre of the stud - if below the surface, given that the cyl. head is al. alloy, I might try refitting the exhaust manifold to try to guide the drill bit. Or I might drill a hole is a piece of steel plate, align this hole with the exact centre of the broken stud, clamp the plate to the cyl. head and use it as a guide for drilling the stud centre.
There are stud extractor sets that include guide bushes for the drilling process. I prefer to use a spline type of extractor rather than the tapered screw type. E.g. :-View attachment 465535

View attachment 465533

In my early days (with very few tools and even less money) I used to drill 2 holes, a small one the full of the broken piece of stud and a larger hole halfway in, then tap the tapered square tang of a file in and use this to wind out the broken stud - if done gently, this often worked but if the tang of the file broke off in the broken, stuck, stud...

An even easier way of removing studs broken off below the surface is not to use any penetrating oil, just use an arc welder to stick a flux-coated rod to the broken stud, disconnect the rod holder, allow the heat to spread into the head and then try using the welding rod to wind the stud out.

This is also how a broken head bolt can be removed in situ without having to remove the cylinder head...
And if a cyl. head bolt were to break, the broken threaded piece (the fracture point will usually occur in the threads that were not engaged with the threads in the cyl. block) will not be tight so should be easy to unscrew and remove. So, no big deal.

Excellent - thank you. I have succeeded in removing the broken piece with a drill, some oil, a tapered extractor and 1/2 pound of patience. And the threads are okay! Whew.

 

[smahaley]

Update: I’ve reinstalled the crankshaft, following the steps in Haynes. I *think* the cylinders are done; I’ll begin putting the pistons in this afternoon. Here’s a video:

 

[Slotman]

Great video! Your really coming along...I saw Bayless had complete gasket sets on sale if you need one...

 

[smahaley]

Great video! Your really coming along...I saw Bayless had complete gasket sets on sale if you need one...

Got one!

 

[smahaley]

Okay question: i cannot seem to find torque spec for the crankshaft end bearing covers (each with 10mm bolts). I found one reference online for 59 ft:lb, but no mention in either the Fiat service manual or the Haynes. I must be missing something ? I don’t want to over or under torque….

 

[124BC1]

Okay question: i cannot seem to find torque spec for the crankshaft end bearing covers (each with 10mm bolts). I found one reference online for 59 ft:lb, but no mention in either the Fiat service manual or the Haynes. I must be missing something ? I don’t want to over or under torque….

Iirc, your engine is a 1756cc unit, correct?

My Haynes manual only covers cars up to 1977, and gives the main bearing torque figure as 59 ft.lbs, however afaik, this figure only applies to 10mm bolts.

Iirc, later 1756cc engines used 10mm bolts on the front? bearing cap and 12mm on the other bearing caps, the figures then became 59ft lbs for the 10mm cap bolts and 85 ft.lbs for the 12mm bearing caps.
Just to clarify, Tightening Torque figure for 10mm bolt (head size = 16mm) - 59 ft.lbs.
12mm bolt (head size = 19mm) - 85 ft.lbs

Iirc, you purchased a copy of the Pininfarina Spider 'Shop Manual as recommended by @Slotman, does this manual not give these torque figures?

 

[smahaley]

Iirc, your engine is a 1756cc unit, correct?

My Haynes manual only covers cars up to 1977, and gives the main bearing torque figure as 59 ft.lbs, however afaik, this figure only applies to 10mm bolts.

Iirc, later 1756cc engines used 10mm bolts on the front? bearing cap and 12mm on the other bearing caps, the figures then became 59ft lbs for the 10mm cap bolts and 85 ft.lbs for the 12mm bearing caps.
Just to clarify, Tightening Torque figure for 10mm bolt (head size = 16mm) - 59 ft.lbs.
12mm bolt (head size = 19mm) - 85 ft.lbs

Iirc, you purchased a copy of the Pininfarina Spider 'Shop Manual as recommended by @Slotman, does this manual not give these torque figures?

Thanks @124BC1 - Yes I bought the Pininfarina shop manual, but that too does not (or I didn't find it) list the torque spec for those bearing covers. They are all 10mm bolts (fore and aft) on the 1756cc motor; so I think I will go with your recommendation. And the one reference I found was for 80nm which does turn out to be 58/59 ft/lb... Oh and my Haynes covers up to the 1980 model...

 

[124BC1]

View attachment 465533

If you look at the items in the right hand tray ^^, you may notice a broken twist drill and that one of the broken thread extractors has been twisted at both ends thereby locking it's removal nut in place - this is what can happen when you loan tools to someone who might just be one of the 'ignoranti'.

I forgot to mention another tip re. removing a broken stud - some suggest using a left hand spiral/helix drill bit - the thinking being afaik that as you drill in, in a counter-clockwise direction, the force may unwind the broken stud, especially if the drill bit tries to snag/jam.

 

[Slotman]

Thanks @124BC1 - Yes I bought the Pininfarina shop manual, but that too does not (or I didn't find it) list the torque spec for those bearing covers. They are all 10mm bolts (fore and aft) on the 1756cc motor; so I think I will go with your recommendation. And the one reference I found was for 80nm which does turn out to be 58/59 ft/lb... Oh and my Haynes covers up to the 1980 model...

Not sure if this helps but it's from the Pininfarina manual..