27 replies to this topic

[KJM]

A question about ARP head studs;
The length of thread where they go into the engine block is different to my old standard studs.
This means that when screwed all the way in, there is some poking out above the block face (see pictures)


Here is an ARP studs compared to the old stud as fitted


And comparing the length of thread on the bench


Question
Is whether this is normal and if its ok?
Or, will I have to deepen the thread in the block?!

Thanks

[MIGLIACARS]

mmm never noticed this before .  Were did you get them??

[KJM]

I got them from MED engineering, just a normal 9stud kit

[minimans]

Have you run a plug tap down the threads? may clean out enough to allow deeper engagement?  Hows the overall length compare?

[KJM]

Have you run a plug tap down the threads? may clean out enough to allow deeper engagement?  Hows the overall length compare?

I did run a tap and also a thread repair screw (like a tap but flat bottom) on one of the holes but no joy.
Overall length seems a tad longer, so I assume that there would be more thread sticking out above the head nuts. I can get a photo tomorrow of the compared.

[Spider]

They should be wound in all the way. The threads in the block are fairly deep, so they may (and usually do) need a clean up. Really, a Thread Restorer should be used as these clean existing threads. A Tap is really for cutting new threads and can in fact damage or take material from an existing thread.

 

The UNC threads on the ARP Studs are longer, so they seat deeper and distort the deck much less. Even so, I always remove the top 1 - 2 threads, this spreads the zone of influence of support out further on the deck and away from the stud hole itself.

[Steve220]

I had this issue, ran a final tap through but whilst doing it, removed it and got the swarf out with a magnet pen. You'd be surprised how much build up at the bottom can top the stud from going all the way down.

[grizzler73]

I always spin a drill that is smaller than the threads by hand or slowly in a drill to dislodge any crud in the bottom of the thread, then blow it out. Also remember to chamfer the stud holes if the head has been skimmed.

[grizzler73]

Sorry I meant skimmed block not head!

[KJM]

Thanks all, tomorrow Ill double check theres nothing at the bottom of the holes stopping the studs going all the way in, but the block was acid dipped before I had some work done to it so Id be surprised if there is much in there!

If there is nothing, would it be totally inadvisable to use the studs with a thread protruding as they are?

[KJM]

So this morning Ive had another look, I got a very small flat screwdriver and scrapped the bottom of the hole, used a magnet, had a drill bit and twisted by hand, sprayed some brake cleaner and then blew out with an airline to ensure nothing at the bottom of the holes... no real difference at all!
However, I put on the How to build a 1380 DVD and it looked like Bill Sollis studs were Similar to mine...
heres some better pics comparing the ARP studs vs original ones

Original has the nut on (LH stud = orig for both short and long ones)

Edited by KJM, 29 December 2017 - 12:09 PM.

[Steve220]

When you tapped them, what stage tap are you using?

[KJM]

When you tapped them, what stage tap are you using?

I used a rethreading tool, which cleans the thread and made it to the bottom (at least I think it did)
On one of them, I used a tap but it wasnt a finishing tap, just a normal one with large taper at the end...

[gazza82]

Do you know if the block has ever been skimmed? That would seem to be the logical explanation.

[KJM]

Do you know if the block has ever been skimmed? That would seem to be the logical explanation.

I very much imagine is has been skimmed as it has had a lot of work over the years. However, a normal stud set doesnt have any threads sticking out!