Head Bolts

[mdm123]

i've a friend who is looking for a set of head bolts. arp don't seem to do them, and the standard bolts aren't strong enough.

the bolts need to be 9mm x1.25mm pitch and 100mm and 85mm long,

so does anybody know of any one who makes headbolts or know of any engines that use a 9mm x 1.25mm bolt.

car is a wee toyota starlet gt turbo.

[Pumaracing]

Even if another engine did use that size of bolt it would still only be the standard 10.9 material spec that everyone uses. If you want something stronger go to a bolt stockist and get 12.9 high tensile caphead bolts. You'll have trouble finding an oddball size like that and you'll still have to calculate a bolt torque to use.

Having said all of the above I suspect the strength of the standard bolts is not your actual problem as it rarely is on any engine. More likely whatever failures your're having are to do with poor surface finish on head or block.

[mdm123]

Pumaracing said:

Even if another engine did use that size of bolt it would still only be the standard 10.9 material spec that everyone uses. If you want something stronger go to a bolt stockist and get 12.9 high tensile caphead bolts. You'll have trouble finding an oddball size like that and you'll still have to calculate a bolt torque to use.

he can get bolts made up, but the fella that will make them isn't sure what grade to use. by finding out what other engines us the same size of studs means he can go to the like of arp and order a set get them.

Pumaracing said:

Having said all of the above I suspect the strength of the standard bolts is not your actual problem as it rarely is on any engine. More likely whatever failures your're having are to do with poor surface finish on head or block.

the problem is the engine is making around 3 times it's standard output.

i'll say to him about the 12.9 high tnesile spec

thanks

Mark

Edited by mdm123 on Friday 31st October 12:45

[stevieturbo]

Have you checked the Toyota GT forum ??

Im pretty sure alternatives are available.

http://www.toyotagtturbo.com/index.php


A friend is piecing together a 4efte, and we had a guy in Malta do the head/cams. Im sure he made us a set of studs...although studs do require some head modifications, so not an easy job.

[mdm123]

There tend to use studs of a 4age, but the problem is the block needs bored to accept the bigger studs. but he thinks there isn't enough meat in the block to take the bigger studs.

[ChrisEvo2]

I had a similar problem with my Lancia integrale head on an old Beta block - the holes had been opened up to 12mm from 10mm but had been tapped using a course thread (1.75). ARP couldn't supply bolts or studs in the length I needed, so ended up using 12.9 grade, cap heads from Unbrako. I got them from here http://www.toolfastdirect.co.uk/acatalog/Socket_Ca...

M9 is an odd size but they may be able to help - could look on the Unbrako site http://www.unbrako.com.au/

Hope this helps.

Cheers,
Chris

[stevieturbo]

mdm123 said:

There tend to use studs of a 4age, but the problem is the block needs bored to accept the bigger studs. but he thinks there isn't enough meat in the block to take the bigger studs.

You can get custom studs made. We did, I just let the guy in Malta deal with it.

But the head area where the new nuts will go, need clearanced for a socket to enter beside the cam followers, that and a thinwall socket.

Obviously a Torx or simular headed bolt, requires minimal clearance for tightening or loosening.


If you can get the head machined, I could maybe organise some head studs. But they would not be cheap.

Edited by stevieturbo on Saturday 1st November 09:40

[350Matt]

If you need custom studs I would go to

http://www.tkprecision.com/contact.htm

They are an excellent firm and pretty reasonable too

Matt

[anonymous-user]

350Matt said:

If you need custom studs I would go to

http://www.tkprecision.com/contact.htm

They are an excellent firm and pretty reasonable too

Matt

+1 !!!

I had a set of studs made in WRC material to my own design for my hi-boost engine, and they turned them around in under 2 weeks at a VERY reasonable price!