Lotus Elan

Head bolt differences

PostPost by: SJ Lambert » Mon Feb 26, 2018 10:28 pm

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?
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PostPost by: 2cams70 » Tue Feb 27, 2018 8:01 am

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
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PostPost by: SJ Lambert » Wed Feb 28, 2018 6:17 am

300b6e9c-a0cc-4156-a9c2-56a295642913.jpeg and


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?
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PostPost by: rgh0 » Wed Feb 28, 2018 8:27 am

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.

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PostPost by: SJ Lambert » Wed Feb 28, 2018 10:45 pm

83f40a26-ab4d-4ca4-89ea-4be52cd2b6be.jpeg and



Thanks Rohan

My special service tool will get less use with the studs now in!!
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Elfin Type 300 (Holbay S65 - 120E) mechanic

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