A Good Ride Spoiled

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.

htown16 said:

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.

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Thatll work for Mick, by now I'm sure he can hit the same torque +- a small amount every time.
For the average home mechanic, tighten securely will give quite a range. Some people will overdo it and rip studs out, some will barely snug things up. If it's not tight enough then the gasket lets go.
Torque wrenches do work to give a very uniform and repeatable tightness.
Experienced mechanics may not need them, but the rest of us can do good work using a torque wrench. A lot of very good mechanics also use them.
Jim uses a torque wrench to measure the exact point of failure. He doesn't do it by feel to get a more accurate result.

Glen

Re valve/guide wear...

FWIW, absent dedicated valve rotators, engine valve gear has a slight 'offset' designed between the rocker arm and the valve stem to ensure the valves rotate during operation. In an OHV motor, the point at which the rocker arm interfaces with the valve stem is not (and should not be) in the center of the valve stem, it is slightly to one side. That offset, coupled with the fore/aft movement of the rocker against the valve stem produces a rotating force. If the rocker hits the tip of the valve stem dead center, there is only forward/backward force applied in addition to up/down and no rotation would occur, resulting in rather short valve live. OHC motors accomplish the same thing, sometimes using variations in cam lobe angle, etc to ensure the same thing - a rotational movement applied to the valve. This means that there are two distinct "sideways" motions involved in the valve train other than the obvious up/down motion, - the fore/aft pressure and the lesser rotational pressure.

In most normal engines, which do not have dedicated rotators, there is little or no valve rotational force at low RPM . So engines that don't see much higher RPM operation frequently don't run very well when taken out for a high speed run. This was a primary reason that "grandma's car," used for local grocery runs, was historically known for its poor running when the grand kids borrowed it

There's an old story re torque settings, allegedly from back in the 1920's-30's: A major car builder had one of their ace mechs assemble an engine as normal in the factory, using the hand tools he always used. Boffins were assigned to then determine what torque had been applied to each bolt and the resulting figures were than published as "torque settings." True? I don't know but knowing the way the world works, certainly seems possible!

Tornado said:

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.

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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?

Hope it wasn’t due to being mushroomed cos if it was, that guide is now screwed...

you can check guide clearance with precision pin gauges. McMaster is a good source for those -

https://www.mcmaster.com/pin-gauges/plug-gauges-7/

baz said:

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?

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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.
There are minor witness marks on all valve tops, all appear about same. No obvious mushroom shaping.

If I wanted to do the guides, what is procedure to remove carbon from lower ends? Blasting (vapour, soda, glass or sand)?

Also discovered one thackery/spring washer on one inlet rocker was bent askew and wasn't giving much rebound. Only one thrust washer found across all rockers. So whoever put head together last was not too diligent.

There are a lot of head experts and workshops around but doesn't mean they are experts on Norton or any British motorcycle heads, back in the 80s when converting my Norton into the Featherbed frame and building my motor for it, the head was handed to a motorcycle head expert and he stuffed up on my head and took only 2 weeks riding to find out the hard way from his stuff up, so don't trust all head experts.

Ashley

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 ?

Time Warp said:

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 ?

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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.

Fast Eddie said:

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.

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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)

an issue I have had with more than one machine shop is not setting the seat width and location of the seat on the valve. one shop did the 45 on the seat topped with a 15 and never went in with a 60. needless to say the seat ran off the valve face to who knows where. it was a funny reaction when I took the heads back and told them to finish the job they started. on another shop that has been around since the 40s I had them do 2 heads for 2 different engines I was doing and I had to take both back for shoddy work. the reaction from this one was he has ONLY ever had 2 heads come back and they were both mine. I guess his customer base is more trusting than I am. all I am saying is good luck in finding a good machine shop and when you do, support them with work and recomendations

Time Warp said:

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)

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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.

Fast Eddie said:

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.

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Correct, they put new guides ( chilled iron ?) in, new unleaded seats, cut the seats never removing any of the KB valves from the sealed bags so yes never checked to the seats.
When I went blue check a seat, they were so rough the KB valve face was marked.
That head will have to go to the same race shop that did my Moto Guzzi heads for new new guides (KB) and see what they can do with the seats (Not one seat has the same face width let alone margin)

Maybe part of the problem is as Bill mentioned, if you can not check something yourself, you would never know, just assemble the head in this case and bolt it on. (That head has been in a bag for years now)
#
JC asked me if I wanted the valves and springs installed in the 750 head he did for, I declined as how could I check it which I did, every seat and guide bore under magnification, blue checked and all were perfect which was no surprise.
Both inserted exhaust port threads were a perfect fit to new rose nuts, all three inserted 3/8 studs screwed beautifully with new AN studs.
A real asset to the community.

I am lucky now I found a good shop that can do cylinder heads and bore cylinders plus another big shop that will grind cranks (and re bores) as you instruct including the fillet radius's, both shops within a 150 km radius.
That is not the case for everyone and perhaps something worldwide now.

#
I have no practical experience with K-line inserts but they seem to have a good name and a viable option.

"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.

Best .

RoadScholar said:

"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.

Best .

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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...

Now we are up to new rods to fix a head gasket.
Aftermarket cases can't be far off.

Glen

worntorn said:

Now we are up to new rods to fix a head gasket.
Aftermarket cases can't be far off.

Glen

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Maybe. I was trying to convey the point, as gently as I could, that repairing any mechanical "system" is a balance of what you expect to get out of it. Installing a head gasket and new valve seals while addressing the valve stem to guide issue (possibly just trying the offending tight valve in the other guide) could be the best solution if the OP continues to watch the revs and the engine loading.

My experience with mechanical systems leads me to believe that half way fixes lead to half way results. I guess the word I'm dancing around is balance; similar to individuals that install high output charging systems and LED bulbs.

Up to the owner.

Best.