Is this head dead?

[Ratman]

Cheers ratty , I always assumed honing would have been a expensive  lathe type kit job , so never really looked into it .  Happy days , as it may mean I can get one of my beloved 056 supers wood hungry again.
knowledge is power ,  many thanks ! 

Just dont over do it! Get an old cylinder to practice using the tool on first, or a piece of old tube or the likes to mock what your going to be doing.

[openspaceman]

12 minutes ago, Ratman said:

Just dont over do it! Get an old cylinder to practice using the tool on first, or a piece of old tube or the likes to mock what your going to be doing.

I have recovered a small number of cylinders now and have never used a hone, just 150 grit wet and dry paper in order to  scratch a horizontal pattern over the damaged vertical scoring to encourage a bit of oil retention.

[Ratman]

I have recovered a small number of cylinders now and have never used a hone, just 150 grit wet and dry paper in order to  scratch a horizontal pattern over the damaged vertical scoring to encourage a bit of oil retention.

Same here tbh, only use the honing stones if the groove is very prominent. Its a gamble sometimes, if its too deep then the cylinder can be a right off anyway, advantage of using the stones is your maintaining the cylindrical shape and not going oval like you can do with doing it by hand.

[Stubby]

7 hours ago, Ratman said:

Same here tbh, only use the honing stones if the groove is very prominent. Its a gamble sometimes, if its too deep then the cylinder can be a right off anyway, advantage of using the stones is your maintaining the cylindrical shape and not going oval like you can do with doing it by hand.

Agreed . a 3 sprung arm hone is self centering anyway so will maintain a true cylinder .

[Rooter]

Gotcha ,  I’ve a few heads lying around that are good candidates to learn on with tool and by hand.  

 Cheers ! 

[Khriss]

Probably dont need to say this but wash ports out thoroughly afterwards to remove grit dust. Fingers  crossed but i think you will acheive. K

[spudulike]

That rod looks like it has seen some heat. How did the previous cylinder and piston look? I reckon the big end was starting to spit its white metal cage out and it took the first cylinder out.

I once had a 346 in like that with ....3 buggered cylinders and a buggered big end no one had noticed before it hit me.

I am still am not sure about the cylinder as those big scores that look like this one can hemorrhage compression as it leaves a significant ring to cylinder gap in one area but would lightly hone it and give it a go as you have nothing to lose. You should have over 150psi compression and a saw difficult to pull over with the decomp valve pulled out. If you don't, it may get better with use but it may well cause an issue.   

[bmp01]

I agree,  the heat pattern says the crank bearing was the hot bit. Gets cooler as you travel away from big end bearing ie up the connecting rod (and along the crank). Ouch !   

Edit - Maybe some of the previously mentioned crap got in the bearing at the first rebuild....

Edited May 26, 2021 by bmp01

[Rooter]

On 26/05/2021 at 18:54, spudulike said:

 

That rod looks like it has seen some heat. How did the previous cylinder and piston look? I reckon the big end was starting to spit its white metal cage out and it took the first cylinder out.

 

Hi spud , I never clapped eyes on the first piston and cylinder, only have the piston and head from the second failure . It came to me partially stripped  in a box with the other bits , as I received it from one of my old bosses as part payment for fixing his crusty 372s that had seized also. The second seize piston shows damage but not loads so and there was not any shrapnel in the crank case but walls of chamber had some nasty gouges in it, the exhaust did have some fine swarf in it like a mouses whisker in bits 
I’ll talk to Tom and find out who did the first fix . Perhaps I’ll cut the rod off too to see what’s left of the bearings to quantify what came out , but the cranks so floppy it feels like there’s nothing in there , making me think that your line of thinking is correct.