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Hi All, Here's the tip of valves...The really ugly looking adjuster in post #120 was on valve that was spinning. Right exhaust.
I've seen several HUNDRED Triumph valves & rockers in my time and strangely, have never seen a single valve with the tracks in a line like the ones in the pix, nor a single rocker with ball damage like the one you referred to in post 120. What are the odds, I wonder?
 

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Discussion Starter · #142 ·
Hi All, Thanks for the tips.
I’ll take another look at the mushroom adjusters.
Web search shows most are slot head, A few Allen head. Which ones do you run? Do you have long term road experience? I would want ones with known durability. Thanks.
Don
 

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Discussion Starter · #143 ·
Hi Chris, Valves rotating is an interesting subject. Some have positive rotator built into spring seat. Gives very good sealing but can wear seat & valve face more quickly, as well as guides. Offset rocker arm/adjuster screw can be used to rotate. Some the spring/valve assembly rotates, some keepers built such just valve rotates. OHC buckets rotate. The valve may or may not. If not tip of valves wear wear a point in center. If shims used on stem you need adjustment where does that leave you? My old Jag did that. I ended up finding used worn shims of different thickness. Must have had cams out 10 times!
Back to our bikes I don’t see many rotate at all. This can wear seat oval. So any time I remove valve I give it a light “check lap” to see. Then lap as needed.
New Mercedes don’t rotate. Changed the valve life to worse. Still very good overall though.

I used to think if I built Triumph motor such & such way it would last really long time like 70-90k miles. I don’t believe that anymore.
Piston inches of travel per mile is too long. They don’t oil well & don’t cool well. Quality parts hard to find or not made. However thoughtful build of motor using best parts available. Quality machine shop work very critical. Oil quality very critical.
Together this is best we can do. Will be interesting to see how long my build lasts. Truth be told, I don’t know if it will make that much difference. Maybe 5k miles tops.
High rpm on these motors is hard on them.
I can say positively, flattening & refinishing surfaces & thoughtful use of modern sealants, viton orings, these motors can be made oil tight. They stay oil tight about 5-6 years. Then PRT seals tend to seep.
Don
 

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Hi, My ‘73 the shaft bears against 3/8 washer same as early unit 650. It has taper, then a flat down low against the washer.
I don’t know about pre unit.
I’ve never had 500 apart. I don’t know on them.
Don, on the 500's, the earlier rocker shafts (70-3748) bear against a washer, the later ones have a taper that goes right down to the reduced diameter and bites against edge of the hole in the rocker box. This avoids a tendency for the shaft to rotate as the domed nut is tightened up, very useful if you have done the groove mod to the rocker shaft and you want to ensure that the groove is located at the top in the unloaded zone of the rockers.

753875


The rocker shaft on the left is the later type (71-3301) with a taper. Incidentally, you can see the straight oil groove mod that has been cut in the shaft to improve the oil feed to the rockers and valves.
 

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Discussion Starter · #145 ·
Hi Grandpaul, I'm not talking about the rocker ball. I'm talking about the wear on adjuster screw tip.

You certainly have way more experience than me. Way more!

I don't know what the odds are. I find it interesting though how there can be these differences.
Don
 

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Hi Don

Peg, if roller is same width & center line as ball wouldn’t it position crank the same as ball? Does roller have same end play as ball?
Yes, the special roller will align the crank the same as a ball bearing.
Just like when you set up the crankshaft fitted with a ball bearing you can easily move the crankshaft to the left by shimming either the bearing or the crankshaft. If you need to move the crankshaft to the right that is difficult.
This way you can make sure the con rods are centralised in the bore

With the pinion nut loose you can make sure you have enough expansion room at the drive side bearing (4 to 15 thou). I I like to dial guage the drive side on with the crankshaft fully over to the left, then see how much it draws back when the pinion is tightened. Even if it is in tolerance it is easy to shim the bearing closer to the minimum.

Norton produce 3 thou Commando shims that fit behind the bearing.
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Peg, did you record the diameter of right crank journal where the ball bearing was on the '74 or later ones? Or do you recall how tight ball bearing fit on crank?
There is not any real interference fit on the timing side between the crankshaft and the bearing inner race, maybe half a thou . A hand fit when the bearing is warm (plastic bag in boiling water) and the crankshaft has been in the freezer. As long as it’s not loose and sits concentric, it is going to be clamped up hard by the pinion nut.
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Just a couple of notes:
Mushroom tappet adjusters, I have seen posts where it is said they do nothing, but the principle is so simple even I can follow the logic in the description; If you grind the radius of the mushroom to exactly the opposite arc of the descending rocker arm, then the mushroom will roll across the valve tip instead of sliding across, the friction, side loading of the valve is reduced, discouraging wear.
I like the principle, it’s easy for me to understand, so I always fit them.
Two downsides are they are heavier than standard adjusters, if you ride in the high revving range this might be a concern.
you cannot remove or fit them with the rocket cover in place.
I have used Norman Hyde adjusters, mainly because he was the original vendor for them, they are available in cei and af threads forms.
The mushrooms have to be hard, but the threads must not be brittle. They use a technique of copper plating the threads to prevent embrittlement, look out for this if you decide to purchase some
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I don’t think think I’m going to cc heads.
I think of matched combustion chambers as the last step in balancing an engine.
If the combustion chambers are the same size then the compression ratio’s are the same each side.
This results in flame fronts travelling at the same (similar) speeds, cylinder pressures and power outputs the same (similar) on each side.
Hopefully leading to a smoother running engine.
I like to see the combustion chambers within 0.2cc of each other.
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We have to assume the pistons are sticking out of the barrel by the same amount.
Thriumph used to bolt the cases together with a mandrel in the crank journals, the use the mandrel to guide the cutter to machine the assembled cylinder base opening. Resulting in a face parallel to the crankshaft.
But someone thought they could make a much cheaper solution by making two jigs and machining each half separately.
If your crankcases were machined with the original method then you are lucky,
The later method produced some interesting steps between the two crankcase halves where they meet in the middle.
If there is a 5 thou (I have heard of 15 thou but have never seen that much) step, then the barrels will be out of line with the crankshaft by that much, and one piston will be that much higher in the bore snd the compression ratio will be higher.
If you don’t have a mandrel for the crankcases, if you lock the bare crankshaft in various positions, you can measure down to the big end journals. After several measurements you can determine if the crankcase flange and crankshaft run parralel. On an assembled crankshaft, a mandrel through both con rod little ends and some feeler guages can be used to determine crankshaft/crankcase parallel.
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If you cannot find original NOS Vandervell, then Clevite is next best.

Regards
Peg
 
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I have measured 650-750 combustion chamber volume that average 69-70 cc ....Just how much difference in compression will .2 cc make ?. Do you grind valve seats or remove chamber material..?
 

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These are hemi head engine, so the piston dome pushes up into that flat volume measurement. For hi dome piston racers you will end up with about 28-30cc volume remaining, for Don’s 7:1 engine around 50cc remaining.

If you find a difference then you can start measuring to find where the difference is.
In the photos of Don’s head when it first came off, the right valves look to be sitting lower in the seats than the left, so I suspect there might be a difference in cc volume on that head.
If you find a difference and it is not in the casting then you can let the cylinder head shop know before they start work.
 

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Discussion Starter · #150 ·
Hi All, I think the seats were actually pretty close. Valve stem height is only a few thousands different. Who knows what seats will clean up at.

Regarding the adjusters they still rub similar to the stock type. Is the radius more desirable? I don't know. Reading about sliding surfaces the material & hardness is a big factor in wear. Lube is what it is for the valve tip. I'll move the flat washers for rockers & visually see if I find any difference visually in flow. My hunch is it will not matter, but who knows.

I've not worked on motor for a few days. Been working on house. Now I'll get back to work on motor.
Don
 

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These are hemi head engine, so the piston dome pushes up into that flat volume measurement. For hi dome piston racers you will end up with about 28-30cc volume remaining, for Don’s 7:1 engine around 50cc remaining.

If you find a difference then you can start measuring to find where the difference is.
In the photos of Don’s head when it first came off, the right valves look to be sitting lower in the seats than the left, so I suspect there might be a difference in cc volume on that head.
If you find a difference and it is not in the casting then you can let the cylinder head shop know before they start work.
Yes ,I measured the chamber and dome volume when I closed up the quench on my 750...I don't write anything down but I believe the difference between the two cylinders was less than .5 cc.
 

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Discussion Starter · #154 ·
HI, In the mean time, I removed roller race from left case. Heated 25 min 300f. Bearing didn't drop out by gravity as I'd hoped. However dropped out slamming on work bench. So wasn't that tight. Bonnie Shop video states later motors the bearings tend to fit tighter in case. I can't say one way or the other. Don't have enough experience.

The ball bearing felt perfect turning crank by hand pistons in out. I couldn't feel play. However the race was failing fast! Outer race looks ok, balls just barely starting to pit. Inner race has critical in about 15-20 deg of the circle. I could hear an odd growl at start up. Once running a few miles noise went away. But not obvious or loud yet. I expect this was cause. Can't say why quiet hot motor. Maybe more oil on race?? I'm going to make every effort to fit timing side roller.

The drive side roller looked fine. Sure a bearing with miles, but no sort of obvious wear or pitting. No clearance markings I could find, so I'll call it OO or CN.

Now I'll have to reread the size factory usually fitted for '73. How does the ball at C3 relate to the roller clearance?

Peg, Mick, Help? Does the timing side roller have clearance markings?
Don
 

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Hi Don,
I have never seen a C2 or C3 rated timing side roller. I have only ever seen standard.
C3 is loose, I have never seen a C3 main bearing fitted ever before. In fact I have only seen CN fitted to the timing side.

I have only ever seen the CN/C2 debate about the driveside roller, never the timing side.

150 degsC and a table slam seems pretty standard for removal though, that does not seem overtight. Although that is probably not the best judgement method.
Triumph bought a burnishing tool that rolled out irregularities on the later engines crankcase bearing housings , they could achieve much tighter controlled tollerances.
Regards
Peg.
 

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Discussion Starter · #156 ·
Hi Peg, Thanks. I don't know what to use yet. I'll trial fit the ball bearing on crank with it on bench then use bearing splitter to remove it & fell pull, compared to drive side. That will give me an idea of how tight ball inner race actually fits. I've read on web there is a C3 timing side roller made?? I'll have to find it again. Apparently theT140 crank journals were changed back to 650 size some time in '76??

Here's an old post. Regarding roller timing bearing. Reply # 121951 speaks of 60-7362 C3.

T140 Main Bearing & Frame Upgrade - Britbike forum

I simply don't know.

Looks like various brands have brass, steel or plastic roller cages. Looks like NSK has both plastic or steel. Any advantages? At work we saw fractured plastic cages on roller bearings occasionally. But who knows why.
Don
 

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Discussion Starter · #157 ·
HI All, My wife is a gem!! She gave me verbal permission to use oven in our kitchen. I surgically cleaned cases of every trace of dirt & oil. Still some oil wicked from cam bearings but not enough to drip on over floor or rack. I put a few layers of aluminum foil on oven floor just in case. Personally I didn't think the stink was so bad. Reminded me of the days at the Porsche dealer when we did hundreds of transmissions using heat & deep fat fryer with oil in it. She didn't like the stench, but it really wasn't that bad. I put the 2nd oven rack over glass window, in case bearing should fall out & hit glass when removing cases. Nothing fell out. I carried case to garage just steps away such bearing couldn't fall out & damage floor.

After heating both sides & removing bearings. I removed the foil & rack. Heated oven to 400f for 30 min. to burn off any oil smells. Use large fan with doors open to clear the air from kitchen. Scrubbed racks well in garage sink. Put them in oven for 15 min. at 400f. So all together oven ran at 400f 45 minutes. No more oil aroma from oven. Left oven door open & the big fan running a few hours. Later when our daughter dropped by I asked her if kitchen smelled funny or odd. Wife standing right there.... She said no! I knew I was in the clear. So indeed it's possible to do this. A normal gas oven.

Back to important stuff... My infrared thermometer is a very cheap brand. Wall thermometer in garage read 76f as did the themo gun on motor case setting on bench overnight. However the case read inconsistent in oven. It actually tool much longer for the thick parts of case to absorb the heat than thinner parts of case. I think I could have left the right case in a little longer. Was 20 min, but from cold oven. I expected case would heat as oven warmed.

I was more mindful of the 2nd case (left). It was in 30 min. Oven had cooled to 150f at the start of heating. 25 min. the top case half bolt boss at rear of primary was 300f according to gun, but 250-275 at main bearing area. 30 min. it read inconsistent 280-290f near main bearing where case is thick. This bearing came out pretty easy with just a bang on the bench. Maybe the right case should have heat soaked longer??

In any case you need to be ready with driver if needed. So have blocks already at hand & know what the set up will be.

Since I'm replacing trans bearings as well I had blocks set up to do that job also. Needle comes right out at this heat. As soon as main race was out I went straight to trans bearings. Turns out the trans bearing fell out on it's own when I was slamming on bench to remove main. I did have blocks & driver standing by as I didn't expect the high gear bearing to fall out.

On assembly I'll install main bearings first. Then move to high gear bearing, finishing off with left layshaft needle brg. I may need to add some heat with torch if case cools durning needle brg fitment. I made to per shop manual. It works good. Stops bearing right depth & clears the thrust washer dowel.
Don
 

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When sealing the end of the closed roller bearing in the gear box part of the crankcase, i used JB weld. That has remained leakproof for many years now. JB weld is very oil and petrol proof in long term use.
 

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Hello Don, sorry I am a little late on this one, but I have used the NSK NUP306ET bearing, not marked with a clearance, so must be CN. You can tell on assembly if a bearing is too tight, I have seen this in pre-unit engines with a C2 drive side bearing - they have to be CN where you can use a C2 on later unit engines. I don't believe that the interference on the inner spool makes much difference for clearance, but in all the applications, the outer race does get crushed down, though the clearance does increase as the engine warms up - witness your exercise with the oven! Much of my experience is with pre-units being updated with various T140 parts, just a few "straight" T140 motors.
PS have you had a chance to measure a T140 rocker spindle end cap groove, I'm trying to nail down the differences in O rings?
Cheers, Mick.
 

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John Healy
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J
Joined: Mar 2005
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Boston, Massachusetts
Brand Model Year Bearing Type Location Clearance Rating
Triumph Unit 650CC 1963-1971 Ball T.S. C3 (70-1591) used up to engine #GE27207
Triumph Unit 650CC 1971 Ball (Metric) T.S. C3 (60-4167 aka as 70-3835) used after engine #GE27208
Triumph Unit 750cc 1973 Ball (Metric) T.S. C3 (60-4167 aka 70-3835)
Triumph Unit 750cc 1981-up (Metric) T.S. Roller CN (60-7362) - Yes, CN!

Triumph Unit 650CC 1963-1965 Ball D.S. C3 (70-1591) - RHP MJ1 1/8-C3
Triumph Unit 650CC 1966-1972 Roller D.S. CN (70-2879) - RHP MRJ1 1/8-CN
Triumph Unit 750cc 1973-1976 Roller D.S. CN (70-2879) - RHP MRJ1 1/8-CN
Triumph Unit 750CC 1977-1982 Roller D.S. C2
Triumph Triple 750cc 1969-up Ball D.S. CN (70-1591) - RHP MJ1 1/8-CN
BSA Unit 500CC / 650CC 1962-1965 Ball D.S. C3 (67-1240 aka Triumph # 70-1591)
BSA Unit 500CC / 650CC 1966-1972 Roller D.S. CN (68-0625) Hoffman RM11L (Currently RHP MJ1 1/8 (Triumph #70-2879-CN) is supplied and shim cup 71-3288 should be used)

It is important to note that in two instances Triumph changed the internal pre-fit clearance specification of bearings without changing the part numbers:
70-1591 used in a Trident D.S. is CN. The same 70-1591 bearing in a Twin is a C3. They should not be interchanged.
70-2879 used in a 650 and early 750 twin is CN. The same bearing used in a 1976-up 750 twin is C2.
John
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Hi Don
I copied this from a thread in the other place 😊
It has theJH pedigree.
It is a funny thread drifting off into Commandoland, but eventually JH but confirms that the TS roller bearing is CN and not the C3 spec used on the Ball bearing.

regards
Peg.

 
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