Cylinder Head Bodge

[oldchieft]

Has the art of blueing and scraping been lost for small bodge fixes?

It was what my uncle called knife and fork engineering, but I would give it a shot before line boring.

Jon the Chief

[billwill]

Has the art of blueing and scraping been lost for small bodge fixes?

It was what my uncle called knife and fork engineering, but I would give it a shot before line boring.

Jon the Chief

Good point, I still have my little steel T square tool made laboriously by hand rivetting and filing and finally blueing & scraping to get perfect surfaces on an 'apprentice' summer course at AEI Rugby in 1960.

And a pair of measuring callipers.

[StressCraxx]

Hi Chancer - yes I was surprised when the "stud" disappeared.

I looked down the hole and saw daylight.

And yes I'm with you - this is the sort of bodge up that I would have been proud of 40 odd years ago

I hadn't considered fitting the coil from below - nice idea.

What variety of Loctite are you advocating for sealing the bottom of the hole?

Instead of a heli-coil, have you ever considered a keensert? I have used these on a several alu heads to repair pulled exhaust studs. They hold much better than helicoils, but they require a larger hole. They would still require sealing the back end.

http://www.specialty-fasteners.co.uk/products/threaded-fasteners-thread-locking/keensert-inserts

[rgh0]

I just realised why the bodge may be was done. The bearing cap alignment hollow dowel would potentially loose its location if you drill out the stud hole for a helicoil or other insert. You need to check the diameter of the helicoil insert drill required versus the recess for the dowel, If the helicoil drill is larger then you may want to fit it from beneath and then plug the hole rather than drill out from the top.

cheers
Rohan

[AlfaLofa]

Yes Rohan - thanks for that - it does look as if drilling from the underside is the best option.

But all these ideas are excellent - I shall be armed with the information I need when I take the head for remedial surgery.

I've started another thread here concerning the difficulty that I'm also having removing the plugs:
lotus-twincam-f39/spark-plugs-refuse-move-t30237.html#p201833

I haven't long had this engine (which also has some block damage):
lotus-twincam-f39/block-welding-query-t30190.html

It came with the head already (recently) separated from the block - but it looks as if the whole unit (before it was dismantled) was open to the elements (or at least very damp conditions) for a very long time.

Also the crank pulley refuses to budge - and I can't even get the distributor out of the block.

Fortunately all the oily bits seem just fine.

[rgh0]

To get the crank pulley off don't use a 3 leg puller on the rim of the pulley as you will break it.
You need to use a bearing splitter and hydraulic puller to get in behind the pulley if possible so you can pull next on the inside rear of the pulley at its hub.

Penetrant down the keyway slot may help

Heat on the pulley and chill spray on the crank down the bolt hole may help free it up so it can be removed by hand without excessive force

sounds like you have a few challenges with this motor but nothing insurmountable so far
cheers
Rohan

[AlfaLofa]

Rohan - when the bolt fell out I was more concerned with reviewing the underside of the head.

Your last post has prompted me to look more closely at the top where the cap dowel fits.

It has already been butchered

Perhaps the best solution now is one large diameter aluminium plug turned for both the stud and the dowel.

If such a plug were to be fitted to the head I'm thinking it might be possible to:

a) Fit the cam
b) Bolt down the 5 cam caps using the 9 good cap studs
c) Use the cam cap hole without the stud as a guide for drilling the plug
d) Remove the cam and drill etc....

Does that sound like a reasonable plan??
(I'm sure there will be something wrong)

[rgh0]

To avoid having to locate the fit of a new dowel and potentially line bore the cam tunnel again if you don't get it precisely right I would try to see if there is enough of the dowel seat left in the head to locate the dowel properly and set the cap in its correct alignment.

If not I would talk to a machine shop about their ability to fit a new dowel in someway without the need for a new line bore. You could just live with one correctly fitting dowel and ensure the cap is correctly aligned by hand and feel on the cam rotation using that one dowel before bolting it down tight!! but that's just another bodge

cheers
Rohan

[alexblack13]

It does look like you might just be able to locate the dowel into the existing hole. As Rohan suggests I would def' try that route 1st. Put the cam in and keep checking it by rotating it as you fit that bearing cap gently and carefully rotation and feeling for any resistance as you tighten the cap up to torque required. I would I think fit the other caps 1st and check free rotation before fitting the damaged one.

You could also, if need be, have a stepped dowel made to fit a slightly enlarged newly machined (Minimum possible would be good) hole. Don't try this at home unless you have the correct kit.. (decent vertical milling machine at least) You must get the cap properly aligned. So.. Line boring would be required IMHO ... Bad dowel position would be worse than no Dowel. It will run without the dowel. Not ideal though.. and def' dont go racing it!! ........

I think you should now (if you have not done so) go carefully over the head and give it a good check over before you start spending dosh on it..

Best of luck with it anyway...

Al '....

[AlfaLofa]

Fortunately there is a good auto engineer (and I mean engineer rather than mechanic) in the local town who has fabricated parts for me in the past. He has all the kit necessary for making, fitting and tapping an aluminium plug. He would be able to do the dowel as well.

I don't know if he does line boring - I haven't asked (yet).

[alexblack13]

Good.. It will workout well I am sure.

Rohan will keep you right no worries at all.

Where are you? (town) ...

Al' ...

[nomad]

Bodge!! What bodge?? Looks like an excellent solution to a small problem to me. I'd just refit with a little attention to sealing around the head of the bolt. Even that would not be much of a problem since there is no pressure on the system and the nut on the other end would most likely seal it.

Kurt
26/3754