Author Topic: Alloy head spark plug threads  (Read 2505 times)

Offline DazSeaton

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Alloy head spark plug threads
« on: 06.08. 2012 21:32 »
Oh dear,
Whilst trying to set the mixture on my 59 super rocket using an old colourtune, I have managed to fire the colourtune across the garage taking with it the last few good threads from the alloy head.

Can anyone give any advice as to the best way to repair, i.e. go down the helicoil route or get the head rethreaded or an insert put in. My first idea is to get the head off and get the valve guides seats hardened at the same time.

Looks like my project for winter!!!
If you don't start, I'm going to give you a damn good thrashing!!!

1959 BSA Super Rocket 650
2007 Suzuki Bandit 1250 SA

Offline baz

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Re: Alloy head spark plug threads
« Reply #1 on: 06.08. 2012 23:46 »
dont use a helicoil use a helisert and make sure the end of the insert dosent enter the combustion chamber or it will glow red and cause pre ignition,as for hardened valve seats i'm sure there will be many different opinions on this i have them fitted to my BSA alloy head but i think it was an unessisary expence ..............baz

Offline a101960

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Re: Alloy head spark plug threads
« Reply #2 on: 07.08. 2012 08:57 »
Quote
My first idea is to get the head off and get the valve guides seats hardened at the same time.
I stand to be corrected, but as far as I am aware the valve seat inserts in the ally heads are already hardened and do not need hardened seats to be fitted.

John

Offline BSA_54A10

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Re: Alloy head spark plug threads
« Reply #3 on: 07.08. 2012 12:18 »
Yep BSA valve seats were forged so they are hard with a capital H
Helicoils are not pressure tight so go for a solid insert and remember to grease the plugs before you put them in.
Bike Beesa
Trevor

Offline DazSeaton

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Re: Alloy head spark plug threads
« Reply #4 on: 07.08. 2012 13:20 »
Well i'm glad i mentioned the hardened seat valves, thanks guys, saved me a few quid there.
So if thats the case I dont really need to use lead additive with the unleaded petrol. double bonus!

I always oil/grease the plugs when fitting, dont think the last 50 owners did though :-(

Baz, whats the difference between a coil and a sert?

cheers
Daz


If you don't start, I'm going to give you a damn good thrashing!!!

1959 BSA Super Rocket 650
2007 Suzuki Bandit 1250 SA

Online RichardL

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Re: Alloy head spark plug threads
« Reply #5 on: 07.08. 2012 13:54 »
Trevor,

I don't see how it matters that the helicoil isn't pressure-tight, given that the pressure seal is at the plug's compressible sealing ring. This is not to say that the insert isn't the better choice.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online Brian

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Re: Alloy head spark plug threads
« Reply #6 on: 07.08. 2012 14:07 »
I havent done one for years but where I worked we used things called "Keenserts", similar to a normal helicoil but once you had fitted them you used the special tool to drive in four pins that are equally spaced around the insert.

I havent seen them for years but they are probably still available. Once fitted they never come out.

Online bsa-bill

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Re: Alloy head spark plug threads
« Reply #7 on: 07.08. 2012 14:36 »
Quote
So if thats the case I dont really need to use lead additive with the unleaded petrol. double bonus!

Hi Daz - although you may well not need the lead additive you might benefit from an octane booster that one of the additives contains, specially for an alloy headed machine
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline DazSeaton

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Re: Alloy head spark plug threads
« Reply #8 on: 07.08. 2012 18:38 »
Quote
So if thats the case I dont really need to use lead additive with the unleaded petrol. double bonus!

Hi Daz - although you may well not need the lead additive you might benefit from an octane booster that one of the additives contains, specially for an alloy headed machine

or use the 98 octane petrol instead of the standard 95?!?!?
If you don't start, I'm going to give you a damn good thrashing!!!

1959 BSA Super Rocket 650
2007 Suzuki Bandit 1250 SA

Online bsa-bill

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Re: Alloy head spark plug threads
« Reply #9 on: 07.08. 2012 19:08 »
Quote
or use the 98 octane petrol instead of the standard 95?!?!?

granted - if you can get it in your locality, it's a bit thin on the ground up my way
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline baz

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Re: Alloy head spark plug threads
« Reply #10 on: 07.08. 2012 19:44 »
Well i'm glad i mentioned the hardened seat valves, thanks guys, saved me a few quid there.
So if thats the case I dont really need to use lead additive with the unleaded petrol. double bonus!

I always oil/grease the plugs when fitting, dont think the last 50 owners did though :-(

Baz, whats the difference between a coil and a sert?

cheers
Daz

now you have got me because i cant remember i think the old type armstrong helicoils were prone to coming out when the plug was removed and the heliserts dig in and lock better but someone else will probably know better than me .incidently if your somewhere 250 miles from home and your spark plug blows out of the engine because of a worn out thread wrap very fine silver paper from a packet of cigaretts around the plug like PTFE tape and you can limp home at 55mph if you go over that speed the plug blows out again also ignore those that stare at you when your ferriting in the roadside bins for more silver paper..........baz


Online muskrat

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Re: Alloy head spark plug threads
« Reply #11 on: 07.08. 2012 20:27 »
 Good tip baz, better than the 5 minute Araldite I used on the VW 30 years ago, that's the last time I've had one blow.
I have used helicoils in numerous alloy heads and never had a problem YET. The inserts are probably better.
Brian, what happens if you strip a Keensert "Once fitted they never come out".
Cheers
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Offline baz

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Re: Alloy head spark plug threads
« Reply #12 on: 07.08. 2012 21:53 »
Good tip baz, better than the 5 minute Araldite I used on the VW 30 years ago, that's the last time I've had one blow.
I have used helicoils in numerous alloy heads and never had a problem YET. The inserts are probably better.
Brian, what happens if you strip a Keensert "Once fitted they never come out".
Cheers
i was on my way back from cornwall to essex seemed to take forever........baz

Online Brian

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Re: Alloy head spark plug threads
« Reply #13 on: 07.08. 2012 23:34 »
Musky I never saw one stripped so dont know !

They are a hardened steel coil like a normal helicoil but with the pins to lock them in place. I had a look on the net and it seems they are still available, here's a link.

http://www.newmantools.com/kee.htm

I havent used one for about 30 years. Before them we used to get a engineering place to fit bronze sleeves but had problems with the insert unscrewing instead of the plug so searched for something else. I currently have a normal "recoil" kit for spark plugs and have used it a couple of times and it has worked well, you just have to make sure you use a anti seize on the thread.

Online chaterlea25

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Re: Alloy head spark plug threads
« Reply #14 on: 07.08. 2012 23:51 »
Hi All,
Wurth "Timeserts" are the answer  *smile*
Copper plated solid steel inserts, little shoulder at the outer edge, special tool cuts rebate for this.
The bottom few threads are not completely finished , the insertion tool then roll forms the thread by expanding the inner end so as they wont come out  *ex* *ex* *ex*

HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)