Aaaaaaarrrrgh !!

Just fitting head back together and got as far as torquing down the cam caps (7 ft/lbs which actually feels quite a lot) when I got that horrid feeling - yes that one when this ain't tightening anymore - bugger !! Just when I was starting to feel a bit pleased with myself too.

So I've got a stripped thread clearly. I also bought recently an m6 helicoil kit to fix a couple of rocker threads which actually now seem ok. The inserts though are only about 6mm long so I'm guessing for decent job I might need longer ones - any thoughts ?

regards (thoroughly pissed off )

James

 

James, it knackered mate, scrap the bike and sell me the 4-1 piper race exhaust you bought of fleabay ;-)

Seriously though - I would look at how much thread the bolt is actually engaging when fitted normally (cam/cam cap on). It may well be only 6mm anyway. Just make sure you use the drill supplied with the kit to prepare the hole deep enough so that the bolt cant snag on any remaining thread if its length exceeds the helicoil depth.
good luck

Phil.

 

Thanks mate - looks like it's actually about 12mm of thread - from what I gather helicoils come in length multiple of teh thread diameter 1d =6mm etc.. So looks like I will need a 2d insert.

sadly too far down teh road now to scrap it - spent 100s messing about with this 600 transplant etc.. - plus I do have a spare head if it comes to it..

Still bugger all the same. I've tried to explain the swearing to the wife but she's not really getting all this camshaft business..

Cheers

James

PS I was (is!) an Alfa-Micron and very nice it looks too ;-)

 

Only joking about scrapping it, I just want that exhaust!

I'll go and look in the garage to see if I have a deeper m6 insert.......

 

Got some 1.5d's and 2d's. Looking at the 1d's your right, that will not be good enough.
If you want a couple and can wait for royal snail to deliver them, pm me your address and ill pop them in the post.

 

Yeah me too.

Not done a helicoil before though so slightly nervous - seen the video though !

Not keen on swapping heads as i just had this one all apart, lapped valves, cleaned AND fitted new head gasket ..

J

 

There easy to do, and you have good access to it as well. I use a battery drill and go slow when drilling the hole out ready for the helicoil tap. The only thing to watch out for is any swarth you generate.
Just remember to keep a little pressure on the insert when your putting it in. You also have to snap the tang of the insert, don't forget to retrieve this from the bottom of the hole
The first one I did years ago I practiced on an old scrap LC engine case. Its a doddle.

 

Thanks - just double checked the actual thread length and it's about 11mm so a 1.5 d would seem best. I appreciate the offer of a freebie but I think they're only a couple of quid for 10 on t'bay..

Will let you know how it works out !

Cheers

J

 

I was always taught that one and a half x dia of the thread was the minimum, so you're looking at 9-10mm

Helicoiling is easy, just keep the drill perpendicular and blow all that swarf out of there

 

Thanks - will do !