Lehman Head STUD.

[Turbonic]

Hello,

I'm looking for a cylinder head stud, that would be a drop in replacement for one of the headbolts that are presently fitted on my engine. (150bhp lehman econ-o-power)

I believe the existing to be 1/2" bolts - but for my own reasons - I am indeed after a stud (and a suitable nut) to perform the clamping.

Any suggestions for replacement would be appreciated, at a push I suppose I could get one machined, but would have to be high tensile steel etc etc - so ideas of places to look/if any one has such a thing going spare etc etc would be much appreciated.

Cheers,
Nic

 

[Plum]

Hello,

I'm looking for a cylinder head stud, that would be a drop in replacement for one of the headbolts that are presently fitted on my engine. (150bhp lehman econ-o-power)

I believe the existing to be 1/2" bolts - but for my own reasons - I am indeed after a stud (and a suitable nut) to perform the clamping.

Any suggestions for replacement would be appreciated, at a push I suppose I could get one machined, but would have to be high tensile steel etc etc - so ideas of places to look/if any one has such a thing going spare etc etc would be much appreciated.

Cheers,
Nic

Hi, I do not have one but you will be taking a risk with a machined stud which will not be as strong as the original bolts which will have a rolled thread. Also, after machining the stud you will not know which heat treatment specification is required to match that of the bolts. If it was my engine I would not take the risk.

www.solocoastalsailing.co.uk

 

[Turbonic]

I completely understand your concerns, in addition its not sure that the clamping force will be the same at the same fastener torque (Bolt vs Nut on the stud).

However in short the benefits outweigh the risks at present.

 

[Machaseo]

The older Ford diesels were stud and nut for the cylinder heads from memory.
try Lancing Marine or a commercial vehicle breaker.
A quick google produced these links:

Cylinder Head Bolts & Studs

13543721 - Ford New Holland Cylinder Head Stud | UK branded tractor spares

I completely understand your concerns, in addition its not sure that the clamping force will be the same at the same fastener torque (Bolt vs Nut on the stud).

However in short the benefits outweigh the risks at present.
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[gordmac]

If you are stuck have a look at ARP fasteners, high end Motorsport stuff but they may do something suitable.

 

[TK Blue MAX]

Get hold of a socket cap screw( allen key type) that's long enough under the head, cut off the head and get a engineering shop to screw cut a thread onto the plain shank, skt cap screws will be 12.9 grade, plenty strong enough for what you need.

 

[gordmac]

Threads are better rolled than cut for fatigue resistance, I would expect a 12.9 to be worse than an 8.8 for fatigue anyway. If you want to cut the head off something use a setscrew but, in my opinion, a very last option. Studs will be available.
The nuts need to be at least one grade softer than the studs.

 

[TK Blue MAX]

The thread on a skt cap screw will be rolled, ARP studs are mostly 220,000 psi which is equivalent to 12.9 i believe, there shouldn't be a fatigue concern on head studs unless on a race engine where they are removed every use and if you were worried about the cut thread , just use a long nut. Just trying to help someone who's asked for help without spending a fortune on ARP products that are excellent , but probably not available singularly.

 

[gordmac]

Indeed, as am I. The forces trying to push the head off are cyclic, every combustion. If the studs are property preloaded they shouldn't see much of any cyclic loading to 2be fair but personally I wouldn't use a cut thread anywhere unless I had no other option.