welding combustion chambers

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ewgoforth

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Hi,

The left cylinder on my bike ate part of a carburetor slide. I rode it like that a couple miles and it did a fair bit of damage. I've found a local automotive machine shop that another machine shop told me could repair stock car aluminum heads that had eaten valves by adding weld and remachining the combustion chamber. I called them and they said they could repair it surprisingly cheaply, although he wouldn't give me a firm price until they see the head. They have a machine that uses the good combustion chamber as a guide. Not sure how that would work some the combustion chamber is a mirror of the other one. I think the combustion chambers in American v8s are identical. Has anyone had success with this type of thing? This shop works mostly on stock cars and four wheelers, which aren't air cooled and I don't think have sand cast heads. I also do more miles than either of those vehicles although I'm not using full throttle nearly as much.

Eric
 
I am thinking you might contact Comnoz and ask what his shop can do with the head.

Slick
 
They can be welded up. It is tough to weld because all the oil and crap will come floating to the surface as soon as heat is applied. The head will also loose a considerable amount of hardness as it takes a lot of heat when working in the heavy sections of head.
The chambers are a mirror image of each other so older duplicating machines can not handle it.

Personally I would find another head if the damage is major.
If it's minor I would clean it up and match the volume side to side. A few little dents will not bother anything. Jim
 
that looks more like a surface peening than what most would consider damage. follow Jims suggestion, have both sides checked and matched for volume. and a gentle cleanup is all i would consider.
 
Pahaws Ms Peel original Combat that processed a thumb nail size slide piece was rather more peckered up that your slight texturing [+ both valve lips curled and exht also chipped]. I sanded down to smoothness again and ran it for 3-4000 miles till stuck throttle got bottom end. Ken Canaga turned it into 920 and now Swain coated and ready to got some more. Auto motive heads generally have more meat so not as structural compromised welded up and cut back. I smoothed the piston too and eventually re-used for a time fine on Trixies till a rod bolt let go. BTW beside comnoz has anyone here actually seen what it takes to "weld" alu, it more like brazing wax forms than like steel.
 
Could Epoxy be used to effect a repair such as this head would require? I know it can be used in intake ports for re-shaping, etc., but can it take the heat of a combustion chamber?
 
Eric, clean up a little bit and check for any significant imbalance in volume between chambers. I would not bother with trying to polish out all the peening; just clean it up a bit. Take off the high spots and clean up and square up around the quench area, especially the sharp edge where it intersects the hemisphere. I have seen and ran much worse.

For what it is worth, you will not need to worry about the valve seats coming out on that side. :D

Per the PM, I have two RH4 heads for sale.
 
No epoxy will stick long in thin layer on combustion surfaces as head heat expands under it breaking its adhesion then blasting it apart to fart right out. Live with smoothed over imperfections you likely can't detect or spend more for another head and break up the old one to prevent some poor soul using its ugliness again.
 
I reckon you could salvage that head by getting it ceramic coated. This basically goes on like thick paint. Flat it down a bit first, get the applier to put it on nice and thick, and flat it back some more.
 
Fast Eddie said:
I reckon you could salvage that head by getting it ceramic coated. This basically goes on like thick paint. Flat it down a bit first, get the applier to put it on nice and thick, and flat it back some more.
Click to expand...

You have any long term experience with such paint? I guess it reduces carbon build up too?
 
Ceramic when used in thick coat on aluminum is likely to fracture and come off. It is very abrasive if it does. Jim
 
OK then its decided by the respected experts you asked to advise, concluded its unrecoverable head that will detonate like crazy so I'd like first dibs buying it for scape please and I'll pay the shipping of course. I suppose ya can also expect the unequal chambers will produce annoying horizontal imbalance vibes the iso can't iso so all the more reason to sell it to hobot and get on with your show.
 
ewgoforth said:
Fast Eddie said:
I reckon you could salvage that head by getting it ceramic coated. This basically goes on like thick paint. Flat it down a bit first, get the applier to put it on nice and thick, and flat it back some more.
Click to expand...

You have any long term experience with such paint? I guess it reduces carbon build up too?
Click to expand...

Yes, I've used it in many race engines. I also have my combustion chambers, piston crowns and exhaust ports treated on my Vincent and Commando. I'm not sure it reduces carbon. It's purpose is to reduce heat transfer, it reduces running temps by keeping more heat in the exhaust gas and less soaked up by the engine. Ref it flaking; this is possible, and is why I always get it done proffesionaly and avoid the DIY kits out there.

This is my treated Commando head and valves:
welding combustion chambers


This is a treated JS piston for the Commando:
welding combustion chambers
 
Fast Eddie said:
ewgoforth said:
Fast Eddie said:
I reckon you could salvage that head by getting it ceramic coated. This basically goes on like thick paint. Flat it down a bit first, get the applier to put it on nice and thick, and flat it back some more.
Click to expand...

You have any long term experience with such paint? I guess it reduces carbon build up too?
Click to expand...

Yes, I've used it in many race engines. I also have my combustion chambers, piston crowns and exhaust ports treated on my Vincent and Commando. I'm not sure it reduces carbon. It's purpose is to reduce heat transfer, it reduces running temps by keeping more heat in the exhaust gas and less soaked up by the engine. Ref it flaking; this is possible, and is why I always get it done proffesionaly and avoid the DIY kits out there.

This is my treated Commando head and valves:
welding combustion chambers


This is a treated JS piston for the Commando:
welding combustion chambers
Click to expand...

I have had it done professionally and done it myself. The pistons and chamber on my injected bike have been done. But it is only a few thousandths thick and would not fill the dents in the head. If it gets thicker than that it will fracture. Jim
 
That peckered head getting cheaper more useless on each new expert's input.
Sexy chambers on FastEddie's that could be yours too.

welding combustion chambers
 
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