Lotus Elan

cylinder head - welding

PostPost by: HCA » Thu Jun 03, 2021 7:10 am

Will the twin-cam head be ok with some external welding?

I removed the screw-in core plug - the one above the distributer - that was seriously stuck in order to fit a heater tap. It was not successful, so I wondered about having a 3/8 BSP alloy fitting professionally welded in place. Assuming I can find someone willing to weld this, does anyone think such work might.would disturb the head in any way?

thanks!
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PostPost by: ericbushby » Thu Jun 03, 2021 7:36 am

I recently had some pitting and small holes on the head gasket face welded before a 10 thou. skim.
They were quite close to the cylinder bore.
The welder and the cylinder head specialist seem to think it was a quite normal thing to do.
It was done while I waited and only took a few minutes.
Not having seen the problem, could the damage be repaired by welding and the thread cut again.
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PostPost by: HCA » Thu Jun 03, 2021 8:18 am

Thanks Eric - you give me some confidence I did not have before!

The heater tap needs to be at a downward angle into the void left by removal of the distributer so as not to foul the intake pipes, so I thought I might as well aim for welding in a 45 degree fitting...
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PostPost by: rgh0 » Thu Jun 03, 2021 10:24 am

I have had a complete combustion chamber rebuild by welding successfully after a dropped valve destroyed it, so with the right techniques the head can be welded without excess distortion or softening.

cheers
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PostPost by: HCA » Thu Jun 03, 2021 10:42 am

Thanks Rohan - I have total confidence now :D I have found someone this morning who says an easy job, but off on holiday tomorrow for a month!
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PostPost by: Foxie » Thu Jun 03, 2021 10:43 am

I did serious damage to the head my 1978 Ferrari 308 engine a while back. I was sure it was scrap.

I made some enquiries, and got good advice where to go.

The result was perfection !

(I've rotated the top pic to align with the bottom, but it still comes up the wrong way round :( )
Attachments
200503Head.JPG and
201008.JPG and
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PostPost by: 2cams70 » Thu Jun 03, 2021 1:17 pm

I'd suggest caution before deciding to take hot coolant for the heater from a part of the cylinder head not designed for that purpose. You may upset the coolant flow and therefore the heat distribution within the cylinder head when the heater is operating.

Also that location is not where the warmest coolant for heater operation is. The warmest coolant always rises to the very top of the engine. That is why the factory takeoff is just below the thermostat. Standard crossflows also have the takeoff at the very top of the engine which is on the intake manifold for that case.

I don't particularly like the idea of hard welding a takeoff elbow to the head either. Why not just keep it original and have the broken fitting removed and thread restored. If you really must you can then just screw in a fitting.
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PostPost by: Foxie » Thu Jun 03, 2021 3:15 pm

2cams70 wrote:I'd suggest caution before deciding to take hot coolant for the heater from a part of the cylinder head not designed for that purpose. You may upset the coolant flow and therefore the heat distribution within the cylinder head when the heater is operating.

Also that location is not where the warmest coolant for heater operation is. The warmest coolant always rises to the very top of the engine. That is why the factory takeoff is just below the thermostat. Standard crossflows also have the takeoff at the very top of the engine which is on the intake manifold for that case.

I don't particularly like the idea of hard welding a takeoff elbow to the head either. Why not just keep it original and have the broken fitting removed and thread restored. If you really must you can then just screw in a fitting.


I'd very much second all that.

:)
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PostPost by: HCA » Thu Jun 03, 2021 3:27 pm

I knew as I was writing that I should not have given a reason! It is always a bad idea! Always a good motto on a forum - ask the basic question and say nothing!

But thanks for your concerns. Yes, the heater will not be as hot as it could - but where I live, who cares? The heater will never be used! Why not use the correct port? It is being used for something else? Yes, I could use a sandwich plate - I choose not to! Heater is not designed to come off the middle of the engine - yep, well done, you are correct! Will it affect things - yes, it might run a bit cooler. but I promise you, the engine will not blow into a thousand pieces :D

Again, thanks and noted.
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