Z1000J Camcap bolts

[LeeJackson]

Well guys I had some success today, changed the helicoils that were damaged however one failed again.. Tried another and same result, so I think I just have too much material loss now. Has anyone tried the bigserts? Wondering if it's worth a shot before moving to something more drastic?

Cheers
Lee

[Ginger Bear]

Lee,

Have a look here;

viewtopic.php?f=4&t=16988&p=150880&hilit=big+serts#p150880

[LeeJackson]

Cheers GB. I ordered a set and will give them a go. Failing that it will be the stud solution.

[Ginger Bear]

Use a pillar drill & set the depth stops! Also from memory I had to turn some 'stepped' dowels.

[Al]

Which ones have pulled out? The ones with dowels or without? Though not a good idea the ones without dowels will be tolerant of a tiny bit of mis-alignment. The ones with dowels will not stand any amount of 'off-centre' drilling! Ray has the entire head mapped out on an index programme and from any location can pick up the exact centre of any of these holes or any other feature which needs machining or attention! I'm not saying that is unique but worth thinking about.
The previous owner of my J head did a phenomenal repair to one of the cam cap threads. Got the hole off centre, and ended up counter-boring the underside of the cam cap and producing an alternative dowel arrangement with a major and minor diameter turned on different centres!!! It works perfectly well but hell what a fiasco and drama.
AL

[LeeJackson]

Hi Al, it's one without a dowel fortunately. Tried a longer helicoil twice yesterday and then tried setting one higher and both failed. So I guess now a Big Sert or goin to the 8mm X 6mm stuf solution is the only way. I was thinking to try an M7 tap also, but I think I've lost too much material for that now. Maybe still worth a try though?

[swampy]

your lucky Lee, i have exactly the same problem on my elr except its on a dowel hole. my headache is the bigsert is bigger than the dowel hole.
so im following this thread intently.
I know this may sound like hijacking the thread but could it be possible for any of you fine chaps to offer a work around.

[LeeJackson]

No chance on M7, I slid a tap in and straight to the bottom definatly not enough material left. So not even enough to tap M8 in this case! Balls. Big Sert will be the only last chance then I guess.

[LeeJackson]

Gents

A grade 10.9 is good enough for the cam caps I assume? I want to go with flange head rather than the cap screws as its obvious the cap screws have been sinking into the caps, but 10.9 is about the highest I can find in a flange bolt.

Cheers
Lee

[Coose]

I would say so. If you consider that the thread is M6 x 1.0mm into an ali head, even 8.8 or stainless would be up to the job!

[LeeJackson]

Coose, I guess that's the logical way to look at it ok good to go then..

[swampy]

8.8 is deffo upto task we used to use them on structural and sub assembly applications such as bearing flanges when i was on the rail.

[Al]

I bought some 8.8 flanged bolts to replace the random assortment i had evolved over time. They were from my local nut and bolt supplier who always have good quality stuff, been in business for decades. They looked the business but it turned out that they may have had 8.8 core strength but the threads were 0.nothing and just pulled along the core. They were'nt the 'rolled thread' type. They were mostly in helicoils but some were still in the original alloy!
Bought the proper things from ZPower in the end. Very expensive but better all round. Sorry but i had to say. To be more accurate; they didnt pull on tightening, they pulled the threads on the bolts after a relatively short spell of running!
AL

[Coose]

Yep, as Al said rolled threads are a must. If price is no object you could always go titanium....

http://www.ebay.co.uk/itm/M6-TITANIUM-Ti-Hex-Head-Flange-Bolt-10-15-20-25-30-35-40-45-50-55-60-65mm-x1-0mm-/121239826611?var=&hash=item1c3a74f0b3:m:mO0C9GSBrbEsyawzdPSHRQQ

[LeeJackson]

Well gents, happy to say I now have my cams back in and torqued down. Thanks for the help! The bigsert did the trick..

One more question which I may be being paranoid about but did a compression test just to confirm I hadn't bent any valves and got 170 on 1&4 but only 155-160 on 2&3. Do you think it's normal or I have an issue?