Head bolt differences

[SJ Lambert]

I?ve used the original waisted head bolts on my Mk16 motor & have got the nervous nellies now that it?s re-torque time (only went to 58).

In doing so I crack ?em off and re torque. I figure I could replace em all (one at a time) with ARP studs?

[2cams70]

You can use ARP bolts (not studs) as better replacements for the originals. Unlike the ARP studs they don't require reaming of the holes in the head for clearance plus they are designed for the original tightening torque. You can get them from Tony Ingram in the USA. See link.


http://www.lotus7.com/ARP_fasteners.html

[SJ Lambert]

Here?s the old ones I took out after using them for one heat cycle.

Studs went in AOK - pulled ?em all up to 56lbs. Should I go around them again at 56 or 58 or leave em alone for a while?

[rgh0]

I find that three re- tensioning steps are needed with composite fibre head gaskets that I use ( the local ones from HJ) to maintain the 55 to 60 ft lbs on the bolts or studs.

1. After the first couple of heat cycles following the initial startup to check for leaks and set up timing and carbs
2. After the first hour or so of operation e.g. after the engine has been driven and run in
3. After the first race meeting e.g. after the first 5 to 10 hours of operation.

After the third step I will get no more movement and often I get no movement after the second step.

cheers
Rohan

[SJ Lambert]

Thanks Rohan

My special service tool will get less use with the studs now in!!

[fatboyoz]

Hi Steve,
Just about to fit ARP studs to my twincam. Looking deeper (too deep), there are conflicting recommendations for torquing the nuts. The Burton site says 80ft lbs, the ARP catalogue seems to indicate 70 to 90 on page 37 https://arpcatalog.com/37/ and Rohan recommends 60 to 65.
I see you have followed Rohan's advice. Have you had any problems, and which head gasket did you use?
Cheers,
Colin.
PS, all this for a waterpump!!!

300B6E9C-A0CC-4156-A9C2-56A295642913.jpeg

Here?s the old ones I took out after using them for one heat cycle.

Studs went in AOK - pulled ?em all up to 56lbs. Should I go around them again at 56 or 58 or leave em alone for a while?