I'm in the process of doing a valve job and renewing the guides I thought I would decarbonize things and remove the guides. I have not removed any guides before and sent the head out last time. Anyway how hard can it be, right? Well I got the intake [bronze ones] out no problem,but the exhaust guides seem to be made of some cast metal and have welded themselves to the port.Of course now they are busted down to nothing and it looks like I'll be sending it out a little earlier than anticipated. I heated the head and removed two little clips around the guides [no mention of said clips in the manuals] but they still wont budge. They are soaking in penetrating oil for now. Any advice would be appreciated.
No of course I didn't use the factory tool. I'm using the "newfie" extractor [large round headed bolt]. I heated the head and nothing is moving on the exhaust end of things.I am rigging up another punch and the guides are soaking in oil. On the bright side of things, the hairline crack I thought I had, is just a flaw [line] in the head from when it was cast,so no welding.
If Norton made an airplane,would you fly in it?
Re: 850 exhaust guides#63684 09/06/057:07 am09/06/057:07 am
The guides are almost certainly cast iron, ideally you would get a machine shop to do this but if you firmly clamp the head you can bore them out with progressively larger drill bits until they are thin enough in the wall to lose their grip on the head casting. A last resort will be to buy a plumbers "pipe freeze kit" and dribble Freon down what remains of the guides after warming the head in an oven.
Speaking of hairline cracks, this is unrelated, but a warning to Commando owners. I had what appeared to be a casting flaw along the top side of a rocker, near the valve end, and I was lightening the rockers so I figured I'd polish it out while I was at it. I ground and ground and the "casting flaw" never disappeared. It had a crack under it than ran parallel to the top of the rocker all the way to the opening at the valve end, and I had to bin it. I'd hate to think what would have happened if I hadn't found it.
"Beer is proof that God loves us and wants us to be happy" - Benjamin Franklin
Tiger, I will probably send the head out, but it was buggin me that I couldn't get them out.I was thinking of tapping them and then getting a large SS bolt and pounding them out but I may try the proggressive drill treatment first. As far as the "line" on my head goes I will file it down a bit but I'm pretty sure it's just a casting flaw. Thanks for the input.!!kk
I ended up taking the head and barrels to Herb Becker . He knows what he's doing and I dont have the tools to do a proper job. I got a valve job and an over-bore with new pistons for a very fair price. He bead blasted and painted the head for me. I'm very impressed.