Cylinder head with issues..

Singles, twins and fours.
User avatar
T Batnes
Holder of a Nylon Anorak
Holder of a Nylon Anorak
Posts: 144
Joined: Thu Nov 08, 2018 10:10 am
Contact:

Cylinder head with issues..

Postby T Batnes » Wed Jan 29, 2020 7:41 am

A cylinder head bought on Ebay a while ago, turns out to have a couple of issues after cleaning and bead blasting of old grit and paint.
Two of the rocker box bolt bosses have been welded up, and not by the best welder out there. The rocker boxes may sit tight, if I get threads in the holes, and maybe I can get the oil to stay put inside by using some epoxy/JB weld on the gasket surfaces before putting on the gaskets. But what worries me a bit, is a couple of vertical cracks that are present in both the nearby head bolt bosses. I could grind out a fillet on top of the cracks, just on the bolt landing, and fill it up with weld, to lock the crack from further expanding. What would you do?
81622454_537339366852325_2100619752299823104_n.jpg

81607642_792430377904538_1316091040213499904_n.jpg

81587317_725574187967566_8202269602617491456_n.jpg
Ariel W/NG '40 "Bitzer", Triumph Thruxton '04, IZH-49 '56, Tempo Standard 150 '54.

User avatar
brenton.roy
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 2056
Joined: Sun Feb 27, 2011 1:13 pm
Location: Adelaide, South Australia
Contact:

Re: Cylinder head with issues..

Postby brenton.roy » Wed Jan 29, 2020 8:34 am

I'd use it as an opportunity to get the whole lot fixed properly. Grind down the shoddy welds and redo if necessary and have the crack fixed at the same time.
'51,'56 Squares, '48 VH, '27 Model C, R67/2, Mk IV Le Mans, '06 Super Duke and Ariel projects.

User avatar
T Batnes
Holder of a Nylon Anorak
Holder of a Nylon Anorak
Posts: 144
Joined: Thu Nov 08, 2018 10:10 am
Contact:

Re: Cylinder head with issues..

Postby T Batnes » Wed Jan 29, 2020 8:41 am

Yes, I was thinking about that too, and contacted a shop well known for fixing cast iron blocks, heads and such - just got their reply back now.... they are thinking 2 full days of work, maybe 3 including machining. Because they had to preheat, weld a little, hammer/forge the welded area, cool down carefully, preheat again, weld a little and so on. All to avoid new cracks to form. Tideous work, time consuming. And at £50 an hour, that sounds a tad expensive. Ah, another paperweight then...
Ariel W/NG '40 "Bitzer", Triumph Thruxton '04, IZH-49 '56, Tempo Standard 150 '54.

User avatar
Vincent.vanGinneke
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 3110
Joined: Sat Apr 09, 2011 12:14 am
Location: "The Dutch Branch"
Contact:

Re: Cylinder head with issues..

Postby Vincent.vanGinneke » Wed Jan 29, 2020 9:48 am

see this thread : viewtopic.php?f=40&t=6601&start=20
It can be done but it takes a lot of time and Dremel bits :D

User avatar
T Batnes
Holder of a Nylon Anorak
Holder of a Nylon Anorak
Posts: 144
Joined: Thu Nov 08, 2018 10:10 am
Contact:

Re: Cylinder head with issues..

Postby T Batnes » Wed Jan 29, 2020 10:35 am

Great info, thank you! I will talk with a welder I know, problem will be to heat it sufficiently without a glass blowers stove I guess. We have acy/ox at the shipyard, and mig.
Ariel W/NG '40 "Bitzer", Triumph Thruxton '04, IZH-49 '56, Tempo Standard 150 '54.

JohnnyBeckett
Holder of a Silver Anorak
Holder of a Silver Anorak
Posts: 965
Joined: Sat Jul 07, 2018 5:39 pm
Contact:

Re: Cylinder head with issues..

Postby JohnnyBeckett » Wed Jan 29, 2020 6:54 pm

i would get it done properly because it has to be hot and arc ( stick ) welded with cast rods not mig and if you cannot get the face 100 % use high temp sealer :!:

User avatar
brenton.roy
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 2056
Joined: Sun Feb 27, 2011 1:13 pm
Location: Adelaide, South Australia
Contact:

Re: Cylinder head with issues..

Postby brenton.roy » Wed Jan 29, 2020 9:19 pm

I have wire welded a head with oxy. You just need to be patient.
Nothing to lose using Vincent's MIG method and plenty of heat via an oxy set.
'51,'56 Squares, '48 VH, '27 Model C, R67/2, Mk IV Le Mans, '06 Super Duke and Ariel projects.

nevhunter
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 3933
Joined: Tue May 10, 2011 9:42 am
Location: Victoria.. Australia.
Contact:

Re: Cylinder head with issues..

Postby nevhunter » Wed Jan 29, 2020 10:02 pm

They usually crack when cooling off after welding ,if you aren't careful to control the cooling.. TIG and MIG are very concentrated heat and you might get hard spots near the edges of a weld. That head will probably run OK if you leave it alone rather than spend heaps on it. Spot face it carefully and see how it tightens down. I doubt any piece will fall out or the cracks go anywhere. Use a hardened thick washer under the bolt head and spot face an extra amount off to maintain thread depth for head bolt.. Nev
Last edited by nevhunter on Thu Jan 30, 2020 3:07 am, edited 2 times in total.

john.whiting
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 1578
Joined: Sun May 22, 2011 2:10 pm
Location: Brisbane QLD
Contact:

Re: Cylinder head with issues..

Postby john.whiting » Thu Jan 30, 2020 2:32 am

looking at the welds ,its looking to me its been welded with pure nickle rod,so the weld shouldnt be hard,might be a hard spot where the arc has struck.......The secret of Vincent s method is heating the head red hot in a low oxygen furnace atmosphere.Then there is equalized shrinkage and slow cooling.....When I was working I used to regularly MIG weld steel cover plates on the hubs of cast iron wheels.Certain shapes of weld contain inbuilt problems ...the worst being long welds with free ends.A concentrated thick spot deposit isnt subject to excessive shrinkage stresses as it cools.......Anyway ,if you have doubts,braze the defects with a brass rod ,or even nickle bronze......Very high strength isnt needed,and the secret of braze weld is the deposit has low strength until way below red heat,so the bronze yields as it shrinks ,and doesnt stress the iron.

nevhunter
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 3933
Joined: Tue May 10, 2011 9:42 am
Location: Victoria.. Australia.
Contact:

Re: Cylinder head with issues..

Postby nevhunter » Thu Jan 30, 2020 3:13 am

It's a lot easier on corners where stresses don't happen as much. Where that head bolt goes is getting towards the middle of the casting where there's more stress created. Why not give it a go as it is? Nothing's going to be damaged and if it works, it's ok.. You don't see it. That model has no head gasket. You double lap the joint. Do both surfaces then continue to lap the outer face a little. Nev


Return to “Four stroke”

Who is online

Users browsing this forum: No registered users and 7 guests