Exhaust studs or bolts

[jackb_ms]

Hi I have seen recently at Aryliam an R500 engine with some studs & nuts to attach the manifold to the block.

On my VVC, the manifold is attached to the block with bolts.

 

Why the difference? Can I fit studs to my block? How difficult would it be? And where can I get them?

 

Jack

 

 

Emily, The Very Yellow 21

[Sheds Moderator]

Bolts make it easier to extract the manifold once undone. Studs make it easier to remount. You can change if you want, but why bother?

[Sootysevener]

Jack

 

try Chris Wheeler at the 7 workshop - mailed me a set of cap head bolts - much easier than nuts on studs or bolts which are a struggle to spanner off given the tightness to the headers

 

David

 

1989 1700XF SS with upgraditis

[Mark Gregory]

Jackb_ms: There is a slight advantage in using studs/nuts in that the thread in the head will not suffer any wear. The head is made of aluminium alloy which is relatively soft, by constantly using the threads there is a risk of wearing the threads & hence causing them to strip. Also when starting to thread a bolt into the head there is a risk of cross threading it & hence damaging the thread. If you do go for bolts make sure they have a generous amount of thread going into the head, but not too long so they bottom out. I would stick with studs/nuts, having said that, my Xflow exhaust has cap head screws - hypocrisy or what...... 😳 But it was like that when I got it!

BOSS: Good to see you responding to questions on screws/threads etc

HTH, Mark

[Normans_Ghost]

I wouldn't fit bolts into an ali head. Studs and brass nuts for me, but I am an old fashion sort of person. I will publish a photo of the first item to be made on my lathe - a 2" long brass manifold nut. 1st one made = £1000, 2nd will be £500 and the 4th and last will be have a costing of £250 each (plus labour and materials)

 

Norman Verona, 1989 BDR 220bhp, Mem No 2166, the full story here

[Sheds Moderator]

Hi Mark. We meet again...

[jackb_ms]

taking the exhaust off, I have found that one of the bolt has damaged the thread inside the head.

According of your advice, I should go for the stud option.

What can i do to repair the thread? Or Can I loctite the studs?

 

Jack

 

Emily, The Very Yellow 21

[SLR No.77]

If the thread is not too damaged - yes you can Loctite it. Also, trim the studs to be only just long enough to accomodate the manifold, gasket and nuts - it'll be much easier to fit the manifold.

 

Stu.

[Nigel Riches]

Hi Jack.

 

If the thread is really munted, then a thread insert may be required, this involves drilling the hole oversize, and with a special tap recutting the thread, then a diamond cross section wire thread form is inserted into the hole with a special tool, this then returns the thread back to the original size.

 

Thread inserts are often used on alloy casting which require bolts to be inserted and removed frequently, so as to save the original alloy material from wearing.

 

So don't despair if it looks bad, most things can be fixed.

 

Regards Nigel.

 

1982. 5 speed, clamshells. B.R.G / Ali. The True Colours.