Uprated head studs/bolts

[Dave MGT]

Just completed the rebuild of 494 head (which is actually the goonys old head)
Looking to upgrade the head studs as it will be running some boost and is a trackcar. So don't want the head lifting!

Now arp do a kit for the t series, but the o series has longer studs on each end....

Just wondered what others have done?

Upside down but you get the idea


Skimmed/faced valves (some were bent) and 4 new valve guides. Shimmed up with a bonkers high lift cam


Someone's done a Nice job on porting the inlets

[Mike Brock]

Hi Dave - Specially made ARP O series head bolts will set you back $700 all in. I know this as I lost out in an opportunity to buy the only known set. The only thing I can suggest is find a reputable engineering shop and get them to make you a set out of some sort of high grade steel. I suspect it will be much cheaper to do this compared with the ARP route?

[Dave MGT]

Thanks for the heads up mike.
Had a feeling I might have a problem with arp studs.
The old block the head came off has some huge 13mm studs. Think I will remove and use them.

[countrydude]

13mm studs

[Guest]

Hello Dave
We never used ARP studs, I don't personally rate them as highly as others do, but anyway, studs are the best way forward. I advise to make the thread in the block M12 (do this using a end mill to make the thread square to the deck) and have studs manufactured either from unbrako bolts, cut heads off and then get a machine shop to cut a thread with an undercut. The TSE1 engine had equal length studs specially made with mass dampers, also there is a Peugeot Diesel head bolt which can do the job as well which has a M12 thread pitch, can't remember the model of vehicle. Make sure washers are large and thick to spread the load, you can either drill out the standard ones which I doubt you will be able to do as they are hardened steel but do make them thick like door steps. Are you wire ringing the block or doing anything to counter the HG blowing?
Also make sure there is no paint between the washer and cylinder head. I noticed these areas have been painted. Gear oil is fine for lubricating the thread before torquing down the head.

[Dave MGT]

Hello !
Thanks for the reply.
Well I have a spare short engine that's been wire rung and has m12 studs in. So for now I'm going to use the std bolts on the block that's in the car (which is std) Then next winter stick a new set of rings and shells in the other engine.
Yep well spotted, I will be cleaning the paint off the top of the head

[Guest]

Sounds good to me.

[Mike Brock]

Hello Dave
We never used ARP studs, I don't personally rate them as highly as others do, but anyway, studs are the best way forward. I advise to make the thread in the block M12 (do this using a end mill to make the thread square to the deck) and have studs manufactured either from unbrako bolts, cut heads off and then get a machine shop to cut a thread with an undercut. The TSE1 engine had equal length studs specially made with mass dampers, also there is a Peugeot Diesel head bolt which can do the job as well which has a M12 thread pitch, can't remember the model of vehicle. Make sure washers are large and thick to spread the load, you can either drill out the standard ones which I doubt you will be able to do as they are hardened steel but do make them thick like door steps. Are you wire ringing the block or doing anything to counter the HG blowing?
Also make sure there is no paint between the washer and cylinder head. I noticed these areas have been painted. Gear oil is fine for lubricating the thread before torquing down the head.

Interesting info team78 - very helpful indeed. I did wonder what those mass damper things were looking at a pic of your engine - now I know.

[Guest]

Hello Mike

The mass damper is a design detail found on long studs in the middle or near one end where the diameter is englarged for a length of 5-10mm
See this link
http://photo.net/photodb/photo?photo_id=1058018
This image shows engine studs fitted to a Rolls Royce Merlin engine. The Rolls Royce Merlin engine is where I first saw it used then looked into why it was done. The mass damper helps to reduce vibrataion fatigue in the stud, this is where the name comes from as it changes the harmonics of the stud but also it helps to keep the stud concentric as well over the distance. When using long studs what can happen when torque is applied on tightening them up is you bend the stud over until it hits the side wall of the hole so the mass damper can be used to keep the stud concentric therefore preventing a bending moment to be caused in the stud. Equal length studs were used to 2 reasons, 1st was the extension in each stud is equal and second they were designed to the highest standard with rolled threads hence costing over £600 for 10!
This is in part because the engine came apart often being a race engine.
The large thick posts were a rush job as it was nearing time for a dyno test and at a later date were going to be revisted to reduce the weight of them. The cylinder head is one of the weakest parts about the O-series and needs all the support/reinforcement it can get.