Author Topic: ali head inserts  (Read 739 times)

Offline spyke

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ali head inserts
« on: 05.02. 2010 19:47 »
Hi Chaps,

On my ali head, which has no broken fins or combustion chamber damage, a few of the rocker box fixing holes are cracked around the bronze inserts. None of the cracks are major and are on one side of the insert only. Can these be left or do they need attending to. I was just going to clean out the crack a little with me dremmel and get a few blobs of tig ali applied...Any thoughts from you .

While Im on, has "the forum" or the Bsa owners club or the like ever looked into getting hard to get items ie cranks , barrels, footrests pistons or whatever manafactured. I know they would be expensive but I know other marques have done this. If a used set of thick flange barrels on plus 40 with a fin gone here and there can go for well over £300 how much would we all be prepared to pay for a nice new set especially in another 5 or 10 years time. After all, like an guy I read about who thrashes his 30s vintage v-twin AJS everyday and breaks a thing or two, says " if they could make it then it can certainly be made now ,somewhere".

Cheers Spyke
A10 spitfire style

Offline 1660bob

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Re: ali head inserts
« Reply #1 on: 05.02. 2010 20:12 »
Good Call Spyke.I am fairly new to the A10 scene, and one of my first observations is the scarcity of barrels.This is probably not helped by reports of re-sleeving  weakening existing barrels at the bottom due to a lack of "meat" here.I believe SRM have had barrels made before, and I spoke to them recently re this.The problem seems to be costs due to a high failiure rate due to porous castings-as the guy said to me "Its ok if you are at BSA and you have your own foundry, any duff barrels go straight back in the pot to be melted down and re-cast!!, but with small batch numbers, its a problem"... Interestingly, at the recent Classic car show i looked at a stand specialising in alloy castings, and there was unmistakeably an ALLOY A10 barrel, rough cast, on the back of the stand, but the guy manning the stand could`nt tell me much about it???- I can`t remember the firms name now.It seems Triumphs are better served in this respect, with alloy /steel linered barrels available-perhaps a way round the porosity issues?and of course no camfollower tunnels to machine... Anyone else know how we can get barrels?? Bob.

Online chaterlea25

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Re: ali head inserts
« Reply #2 on: 05.02. 2010 20:45 »
Hi Spyke,
Regarding the cracks around the bronze inserts
I have been told that some of these have been there since casting, the alloy shrinks faster than the bronze and the cracks occur!!!!
Screw a rockerbox bolt into the threads all the way and try and see if there is any movement of the insert
If there is no movement I think I would be happy enough,also check if the bronze is proud of the face
I dont knonw how the alloy welding would work if you ground the alloy back to the bronze ????
It is vitally important to clean out all the crap that accumulates at the bottom of the insert holes
I use a 1/4 drillbit first and then run the tap down then drillbit again followed by a blast from the airline

I have sent a badly cracked head to SRM for estimate, one insert is broken out completely and another is  very ropey looking, a 3rd insert has damaged threads!!!!
In the meantime I have bought another head on fleabay from the USA, this turned out to be quite a find as it is complete with no damage at all!! and included the rocker box and all the fittings
There even isn't any distortion of the ally around the plugholes or headbolts,
I dont believe the engine had any real miles up and was never apart before *smile* *smile* *smile*

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