.......back to the 70's.
- Dec 3, 2012
With the stems and guides clean condition should be easy to feel, there can be more rocking inline with rocker travel than at 90 degrees to that.
Thatll work for Mick, by now I'm sure he can hit the same torque +- a small amount every time.I've never used a torque wrench on the rear nut or the two long nuts underneath in the front. Just tighten them securely. I do use a torque wrench on the four side bolts and the center front bolt set to 30 foot pounds. Also on the two 5/16 set on 20. When you retorque after the first heat cycle I find that if it takes a half turn or so on the ones I can get a wrench on it also takes about the same half turn to tighten the ones I can't. Mick Hemmings never uses a torque wrench at all in his rebuild dvd. Says just to tighten securely.
Do you mean the exhaust valve was tight to get out of the guide IE the top of the valve was mushroomed?Today I got the rockers, springs and valves out. One exhaust valve was quite tight in the guide and needed a lot of force and wiggling turns to finally get it out. Not sure how The springs could move that one up to close. That one and other exhaust valve had no easily feel-able rocking in the guides. Intake did seem to have some rocking.
It was stiff right from unseating and all the way through. That had more "scorching" on the stem than the other exhaust stem. Will polish it up and see if that clears up stiffness.Do you mean the exhaust valve was tight to get out of the guide IE the top of the valve was mushroomed?
Or was the valve tight in its operational position?
If the guides are tight in the head but need work, perhaps K-Line inserts are an option.
I got a TR5T head done which included new guides and seats, the new Kibblewhite valves were still in the sealed bags when I got it back, riddle me that ?
That’s interesting. I wonder if stuff like that is down to this same ‘modern methods vs old methods’ type thinking, like with the crank grinding / radius topic?
The head on my T140, rebuilt by PO, had tight inlet guides (one had to be drifted out). I can only assume they fitted them and assumed they’d be fine, whereas an ‘old methods’ machinist would know to check and expect to ream.
Yes I agree that K liners etc are a boon for this.By that I meant, if the original valve guides were beyond the service limit (stem to guide wear) but the guides themselves were still a good interference fit (which it must have to be stable) in the head itself, instead of disturbing/removing them from the head a K-line insert to the guide bore might be an option.
Many a head has been ruined by guides being beaten out and one reason for oversize OD replacements.
What used to happen in the old days (or now for people who still use those practices)
Beat guide out.
Beat new guide in with a drift. (Instead of drawing it in with a mandrel)
Run a set reamer down the guide bore. (You could end up with new valves and guides that were perhaps a 60 % improvement over what you had replaced )
Cut the seat off that new bore which could lead to offset and excessive cut ( including having to be lapped)
That is not the case now with the likes of Serdi's and diamond hones. (Thank GD)
Of course even those machines need an experienced and motivated operator.
The problem can be finding a shop that will NOT $#$^^ up your engine parts but will actually want to work on relic parts.
Did I mention Jim Comstock, what a legend (Worldwide and maybe further)
Yes I agree that K liners etc are a boon for this.
What threw me is you said the new valves were still in the packets (not guides) leading me to conclude the valves could not have been measured or tried for fit.
right on the money..! Oh the stories we can tell of what we have seen people do to save a few $... and suffer for it..."In for a penny, in for a Pound" ,"A stitch in time saves 9", "Do it once and do it right". So where do you stop on solving a problem like this? Some have suggested just replacing the head gasket, others much deeper procedures.
Looking at the pictures I see some evidence of vertical scoring and more prominent history of honing. As has been mentioned it is difficult to properly judge without being there. For me the key to making a proper assessment is to strip and measure, measure, measure.
A lot of vintage English bike owners seem to wonder, "how cheap can I got out of this"? Again how much is too much? Conversely how much is not enough? When you rebuild the top end completely and properly the engine will regain full power, but the rods big ends, which have aged gracefully, now have to bear up to greater stress and 45+ year old alloy rods that have seen countless heat cycles might balk at this. Valve springs don't last forever, who replaces them as a matter of course?
I heard, back in the day, "ride an hour, wrench an hour". It doesn't need to be that way. If you replace one leaky fork seal, you'll be back there again soon enough. If you replace a worn chain, you'll be back there again with another chain and a set of sprockets soon enough, Band-Aid fixes cost more, soon enough.
Somewhere, maybe, between a complete restoration and understanding what you have the right to expect from your piece of history, is the answer I have yet to read on this forum.
All the suggestions have some degree of merit, certainly great intentions. You can spend a mortgage or may get lucky with spending a week's worth of grocery money; really up to your expectations: take the "systems" approach or the Band-Aid.
Now we are up to new rods to fix a head gasket.
Aftermarket cases can't be far off.