[dfarah]

Originally Posted by Bill UK

I posted this on the UK forum last month, may be of some interest if you are using ARP studs, Halfords by the way are an UK Auto Parts Supplier.

Last month I did a HG replacement using ARP studs for the first time, on two other previous occasions I've used Toyota stock bolts. I made a couple of drawings that may be of some use for future reference. The first thing you will notice are the studs are much longer than the stock bolts, the existing Toyota stock bolts only screw in the block by 0.608 thou, where as the ARP studs will need to screw in by .808 thou minimum to ensure there's enough thread at the top of the stud for the nut to screw down on to. After lapping the block I carefully cleaned the holes out with a tap just to make sure the stud would screw in by about an inch. As ARP are an US company I expected the socket size to be in inches, 9/16 will fit but 14 mm is a much better fit (smaller by .010 thou.) As mentioned in previous postings the Halfords 14mm, 12 point, long reach socket 2.500 long with a 3/8 drive will fit nicely, that’s of course you don’t have a head like mine. A couple of places on the inlet side the socket wouldn’t go down to the bottom vertically, so I removed the cams to get a better view. The problem was the ally casting didn’t allow for the diameter of the socket (the socket being 0.778dia) So I ground down the diameter of the socket with the bench grinder to 0.764 dia to ensure a good vertical fit, as posted by Bondago. I have also read on Supramania forum about the need to reduce the base of the nut Link fortunately mine where ok.
Hope this helps.

Notes:
1. The outside diameter of the Halfords 14mm long reach socket with a ? drive is too large

2. Snap On long reach 3/8 drive Stock#: BLPLM3814 19.6 mm (0.771 inch) outer diameter, which is slightly smaller diameter than the Halfords one, probably would have fitted without grinding down.

3. It's possible that ARP nuts where once 9/16 so if your removing a head that has ARP studs fitted from some years ago, they could be imperial nuts 9/16.

4. ARP Stud & Bolt info

Nice diagrams & explanation dude. I don't know that ARP nuts where once 9/16. Anyways, thanks for giving these useful infos to us.