Thinners soaked rag stuffed in the hole for 10 minutes softened enough to scrape off with my fingernail, mostly. I can see why Rob used sealant on this head. Perhaps I'll do Mr Westy's trick with a ring of wire in the base of the case holes to shift the seals out a bit.
Looking harder they'll need sealant though at almost 50 years old I can't be surprised. Rob spared me the sealant between o ring and tube. God bless you Rob. O ring to case involves lying in wet mud so that joy will have to wait. I'm assuming he sealed the case end, there are traces on the tubes.
I'm going to slap it back together with another 4-5 ft/lbs, torque. The other side the same without removing it. It went before so it'll go again, blowing or not. Then the immediate pressure will be off. I'm thinking I may follow someone on Samba's advice and have a 1mm copper sealing ring in a machined groove in the head...or maybe not. Either way it'll take time to get the parts from the US and possibly organise barrel shortening and a better valve job, maybe do some match porting. Being mobile will make all that easier.
For whats it worth, I've used 3m green fitted in a slot in a piece of round 8mm wood attached to cordless drill. leaves a smooth clean surface.
I'm struggling to find them at the size I need, 115mm OD. In fact I could only find CB performance type-1, but I guess the biggest of those probably fit your type-4 engine?
It's the case ones that will be awkward but I've managed before with just the lower tins removed to will be easier than that. I won't want abrasion dust getting in the follower bores so scrape, scrape. I used a guitar plectrum on the head but that was awkward despite easy access - need to find something hard enough but plastic and a better shape for the case and I'm drawing a blank so far. Maybe a plastic knife from the cafe.
Old credit card? You can keep trimming it with scissors to restore a "sharp" scraper edge. Cut strips as small scrapers for your little nooks and crannies. You could even cut a curved edge to get around the chambers
Hmmm, that's beyond both my skill and tech. I've read copper doesn't lasser cut well and theirs also the matter of annealing them which I believe for a big flimsy thing is best done in a vacuum. I'll be on the phone tomorrow and see who I can find. Best get the heads and barrels in my hands before actually ordering though, they may well become my deck height shims, I ought to mock all up first so there's another delay I'll have while doing the "big swap".
The rain stopped at last and the wind died down a bit by early afternoon. I've refitted the head and torqued it to 37Nm, 27.3lb/ft. I sealed the head end push rod tube o-rings and oiled the case end. Case end holes were in good condition and the sealant there scraped off without softening it first. That cheered me up so I built up the head and set the gaps then fitted the tinware, carb, manifold, oil pressure sender and the distributor for the tenth time. Can't fit the HX until fan housing is back on properly. I've got the carb and manifold off the other side, removed or loosened enough tin to get at the top 4 nuts and that was enough for today. Next break in the weather it'll be off with the rockers to access the bottom 4 nuts and torque all 8 up from 23 to 27.3lb/ft to match the first side. Not a bad day all in all.
Thanks to some chaps in America measuring some uncut 1700 heads, I've worked out that the main fin has lost 1.75mm thickness and the registers were decked at least 2.5mm. Wow.
