Cylinder head studs

[jaguar68]

Hi Guys,

Can any of you knowledgable chaps tell me what thread the block is tapped with to accept the cylinder head studs?

Regards

John

[IslipMinor]

John,

The block is tapped 3/8" UNC.

[jaguar68]

Thanks, now off to source a 3/8 UNC tap

[bmcecosse]

Oh ohh......sounds ominous!

[jaguar68]

Not quite so ominous. I wanted to take the head off of the 1275cc engine so I could change the head for the big valve 940 head. Managed to undo the head stud nuts (eventually) as they seem to have been done up using a scaffold pole. Slide the head off the studs? No way. The head seems to have grown onto the studs with a fine iron dust. Tap the head with a soft faced mallet, still no movement. Next plan extract the studs from the block, managed to get 8 out of 9 out using a stud extractor on a ratchet, tap the head again with the mallet, still no movement on the last remaining stud.

In the end, I had to "unscrew" the head complete with the seized stud. A 20 minute job took close to 2 hours to complete. I need the tap so i can clean all of the iron dust out of the holes in the block, luckily enough, none of the threads are damaged, just increadably dirty.

Regards

John

[chrisryder]

You probably don't want to hear this now, but you could have put the nuts back on the studs loosely, and turned the engine over on the starter, to try to get the compression to blow it off (hence nuts on to stop it flying off!).

[jaguar68]

Chris,

I haven't managed to get the seized stud out of the head yet!!!

[chrisryder]

Yikes!

Oil, heat and a big hammer?

[jaguar68]

Yeah, I guess thats the next move, along with the last 2 pesky manifold studs that my stud extractor wouldn't unscrew. Good job it's not the head I was planning to use

[bmcecosse]

Make SURE you don't snap that stud - take your time, apply release oil - lots of it. Apply heat to the stud and then let it cool. And perhaps try tightening the stud slightly before again trying to loosen it.