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cylinder head cracked


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Just found out that the cylinder head is cracked between the valves, whats the best option ,repair ,replace with second hand or recon exchange.

cheers

Graham

 

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As Roger says the process of fitting hardened valve seats may well machine out the crack between the valves.

Unlike a normal unleaded conversion where only an exhaust insert is fitted both inlet and exhaust inserts would need fitting - in the process the cracked area is machined away.

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Depending on the severity of the crack it can be pinned. JSWL in waterlooville can help they have just done a friends one cheaper than getting a 2nd hand one bought then checked. Cheers andy

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Thanks for all the replies.

 

I don't know the full extend of the crack yet as I have not been down the machine shop to look at it . the machinist was reluctant to convert it to unleaded to begin with due to leaving very little metal once the hardened seats had been cut back to suit the valves and becoming even more prone to cracking.

 

I am a welder by trade so might have a go at welding it myself then getting it recut but as people will know welding cast is problematic you must get the pre & post heating correct or it will crack again .

 

I will contact a couple of local club members so see if they have anything available ,that might be the easyist and cheapest route.

 

cheers

 

even more stressed

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Hi Graham,

back in the 90's during my 4A rebuild I found the exhaust manifold down pipe cracked at the join between 2 & 3.

I took it to a welder who said an Al/Nickel/bronze brazing technique would do it.

This looked like ordinary braze but obviously wasn't. This lasted a coupole of years before I moved on to an extractor manifold.

 

I would have thought if the crack could be opened up and cleaned, then brazed as above and then recut to take the hardened seats you would have success.

 

However this is all costing money so do your sums first.

Have you put a post in the B uy/Sell/TRade forum - there may be one out there with your name on it.

 

Roger

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I don't think you can fit hardened seats in both the exhaust and inlet due to their proximity, that's why only the exhaust seat is replaced. The cooler charge fuel/air mixture protects the inlet valve and its seat. IIRC the whole head would need heating before welding or brazing and there is a limit to that too before the carbon in the steel changes structure. Not impossible but difficult, maybe with speaking to a specialist weld company.

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Aluminium heads have hard seats in both places.

 

Roger

Agreed but would there be enough room in an iron TR head?

BTW whatever happened to the alloy heads someone was proposing?

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Graham

I cracked a head some years ago and took it to a specialist cast iron welder in Measham, Leics., just off the A42. Can't remember name but he was experienced in repairing rare Vintage vehicle components, etc. However price quoted, without any guarantee of success, together with the need to probably have it skimmed to remove any bow/bend that could have developed in the pre heat/controlled cooling sequence made it economically unattractive. I didn't proceed and bought another head. I could probably find the name if you wanted it?

 

Alternatively, I have another head available (no, it isn't the previously damaged one!!.) It was on a Fast Road engine and has enlarged exhaust valves. The inlet port spacings are the narrow type, as fitted to USA carburettor cars, so not suitable for UK PI induction.

 

It's in Retford, Notts. If interested, PM me for a price.

Dave McD

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Unless the head has had expensive gas flow work done, getting an uncracked replacement is undoubtedly the best way forward. They are not rare or expensive as many of the big saloon heads will provide an equivalent casting.

 

It is possible to fit inlet and exhaust seats together if the crack is not deep, but quite a tricky operation where the valves are so close together and many will not attempt it.

 

Nick

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I agree about the double inserts to machine the crack out but the machine shop is very reluctant to do this.

 

To weld/braze the head would need very careful and intense heat management which could result in a warped /twisted head and would require extensive machining to bring it back and very likely to cost more than a fully recon head from any of the suppliers.

 

Lots of second heads are out there but many are not suitable for P.I engines and you also take a chance with condition unless they have been machined or crack tested before hand.

 

Many thanks dave but as you said the head would not be suitable for my P.I car.

 

I will have to weigh up all the options ,it might as well be the cheapest and easiest route to purchase a new recon head from moss/rimmers/revington etc.

 

cheers

graham

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You should be able to repair this with nickel-bronze brazing.

If you are a welder then it wont cost you much to try.

 

You will need the right rods, temp-sticks and a heat-blanket.

An ordinary OA welder will do fine.

 

Grind out, preheat, fill and cool slowly.

 

I can help with more advice if you go this way.

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You should be able to repair this with nickel-bronze brazing.

If you are a welder then it wont cost you much to try.

 

You will need the right rods, temp-sticks and a heat-blanket.

An ordinary OA welder will do fine.

 

Grind out, preheat, fill and cool slowly.

 

I can help with more advice if you go this way.

 

Hi alan, I have been out off the welding game for some time but keep my hand in on the hobby stuff, what rods would I need to repair the head ,is the head cast iron or cast steel, I have oxy/act and arc welding equipment for the heating and welding process.

its probably worth a go considering the heads f@@ked anyway

cheers

graham

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http://www.ebay.co.uk/itm/Triumph-2000-Cylinder-Head-313248-High-Compression-/301301146415?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4626f2a32f

 

This would do it. Listed as T2000, but the casting number matches up the 219015 (most likely) and 219016 which means it's also suitable for 2.5 and even listed for later TR6 PI. These have smaller exhaust valves so less likely to be cracked. If you are planning to have unleaded seats fitted anyway then valve sizes can be increased at the same time.

 

Useful list of head numbers here

http://www.triumphclub.co.nz/?page_id=653

 

Nick

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