Cylinder Head bolt holes for manifold repairs

[DannyPancho]

Hi all,

Its come to the time when I am now looking to spend some money on making my engine better...

I had to re-bore and thread two of the manifold bolt holes (luckily the ones facing outwards of the car) and also bore the manifolds to fit the new bolts.
As I was using a hand drill to bore the manifolds out, i managed to f'$k up one of them, and as a result, it blows. So i need new manifolds regardless!

Is there any way of having the bolt holes refilled and then bored out again to the original spec?

If so, how much would it cost? Cheaper than a new head?! 

cheers,
Dan

[Gadge]

If you some one with a welder it could be possible to weld up the holes, grind them flat and re-drill new holes.

[DannyPancho]

Yeah thats what I thought, i just dont know anyone with one! i guess i can just have a look on the interweb for local fabricators. Try and get a quote

 

[Gadge]

Where abouts do you live?

[samdavies97]

Hey

I did exactly the same thing. But I found something called a Heli coil. Google them, they are super clever idea and really strong alternative to welding.


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[DannyPancho]

Gadge, I live in a small village in Leicestershire,

and

SamDavies, Ill have a look! ive heard of them but had forgotten about them 
Cheers!

[michaelodonnell500]

What size is the thread now and what size is the manifold hole? I don't think you can go bigger than an m10 unless you have a specific part machined for you. Otherwise the manifold hole will be too weak or the head of the bolt just won't fit.

I've had m10 already installed on an old engine I acquired. Not ideal, but it done the job.

Below are some sizes for helicoil insert pilot holes.

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[Rusty's Uncle]

Welding aluminium is a specialist job requiring the right equipment and not the sort of thing that your average garage is capable of. You would have to remove the head to have any sort of chance of a decent job. Might be worth asking around any engineering companies if you have anything local otherwise a replacement head might be the way to go. I have lost count of how many heads I have repaired by various means. The worst ones by far have been those where someone has tried their own "repairs". If the thread is just stripped then the simple M8 x 1.25 helicoil is the cheapest and most effective way to go. If you have started to drill out holes and retapping with an oversize thread then the chances are that you have no way back as a standard M10 thread has a pitch of 1.5mm so you can not go back to an M8 helicoil with a 1.25mm pitch.

[samdavies97]

Gadge, I live in a small village in Leicestershire,

and

SamDavies, Ill have a look! ive heard of them but had forgotten about them 
Cheers!

Here you go, this is an M8 helicoil that I did on mine.



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[Gadge]

I'm a little confused Danny is it the cylinder head you've knackered up or the exhaust manifold elbow? I was assuming you meant the elbow which I belive is steel which could be re-welded but if it's the head then rusty advice is the best option (unless you buy anther head)

[DannyPancho]

Hi, yeah sorry for the confusion, before i knew what a helicoil was (about 2.5 years ago now) i bored out the cylinder head bolt holes as the threads were rounded out, i also had to bore the manifold elbow on that side to cater for the larger diameter bolt.

I believe its an M10 in there unfortunately, and i suspect getting the head professionally repaired is expensive?

I may just have to go with a new cylinder head when the time comes... maybe even splash out on a fancy dual intake one... in my dreasms 

Ii wish i had known of the helicoils before i bored out the holes, it would have been so much better in the long run

cheers guys

[Rusty's Uncle]

To be honest Dan , like Gadge I also found it confusing so took a guess on what you meant 
No reason why you should not live with the M10 bolts but just a shame as helicoils would have been easier as well. I prefer to fit high tensile studs as once they are fitted to the head there is no need to remove them. You could consider fitting stepped studs , M10 on one end than M8 to suit the elbows. Again another engineering job but quite easily done on a lathe.
It is amazing that the original problematic exhaust design from the 1950's carried on for the entire 500 and 126 range. It was only with the twin port Fiat Panda 30 cylinder head that helicoils were fitted as standard from new. If you are thinking of going that way then there are fitting issues due to the different shape not to mention they are not that easy to find 

[Amateb8]

I used an engineering firm, Jim Stokes Workshops Ltd to repair my Fiat 600 D's cylinder head. It was costly, but there was no alternative.

Their workshop is soooooooooo amazing. They do a lot of the vintage/classic cars (including race cars) were no spare parts exist. They can fabricate all engine parts including carbs, and anything from suspension and bodywork etc.

There were numerous £1mn plus cars in the premises from clients all over the world. Most, if not all, were mint condition.

[DannyPancho]

Not to worry Rusty, I guess trying to explain things isnt my strong suit... maybe its just a sign i dont quite know what im on about 

I did have a teacher at college mention about a stepped studs but i dont have access to a lathe, can you buy them anywhere? Realistically, I need a new manifold elbow, but i didnt want to have to re-bore it if i could help it.

Amateb i will have a look into them thankyou for the reccomendation!

[Rusty's Uncle]

Not to worry Rusty, I guess trying to explain things isnt my strong suit... maybe its just a sign i dont quite know what im on about 

I did have a teacher at college mention about a stepped studs but i dont have access to a lathe, can you buy them anywhere? Realistically, I need a new manifold elbow, but i didnt want to have to re-bore it if i could help it.

I think that I may have an elbow that has already been drilled out to 10mm. If I can find it would it help you get over your immediate problem?