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#836205 01/10/21 6:35 pm
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We've talked about hardened post 68 cams often enough, and how we can delete the pressure feed if using these.
Here's the opposite question, can 1967 cams be expected to last better today, with the better oils we have now, some 50 years on?
The reason for the question is that the current engine on my bench is a 67 Bonnie, complete with the "jiggle pin" lubrication metering system to the cam follower block. The cams, even the exhaust cam, are the originals and in fine shape. It seems a shame to replace them to be honest, and the owner and I are discussing whether to keep them or not.
My own opinion is that I would if it was my bike, but since it belongs to someone else, I'm not so sure.
I worry it may come back and bite my behind.
Experiences and opinions welcome!

SR

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Stein Roger #836214 01/10/21 7:19 pm
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How many miles have they done?

They’ve lasted this long. Why would they not keep on working?


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Originally Posted by triton thrasher
How many miles have they done?

They’ve lasted this long. Why would they not keep on working?
My thoughts exactly. The engine is in a horrible shape, and the crank is ground .010" which suggests some mileage.

Thanks, SR

Stein Roger #836337 01/11/21 5:29 pm
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If this engine has a reground crank, how do you know the cams weren't replaced then and have low mileage? And you're sure they aren't later nitrided? I bought my '66 T120 in '68 and found it had cams that were ground down flat, maybe half lift and ugly, crank is still original journals but mileage unknown. If the cams could be changed from the outside it would be an easier decision, also easier decision if the owner doesn't plan to put any miles on it. Good used '69-'70 cams used to be really cheap on ebay and at swap meets. Triumph bottom ends last a long time if done right at overhaul, for me that would include later production changes such as nitrided cams, deletion of jiggler and install of low flow followers. Just my opinion but cams and 4CA points assemblies are original equipment but neither worth keeping and were changed for good reason...Mark R.

Stein Roger #836415 01/12/21 9:04 am
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Mark, thanks for the opposite view, as it were. You make good arguments. I have no way to tell if these are the original cams, but they do wear the original numbers and they're not nitrided. They may still have been replaced of course. The owner is a knowledgeable man with several Triumphs, and I'll ultimately leave the decision to him. As you suggest, he isn't going to use the bike very much, he's got modern bikes and a 69 Trident for that, but the bike will at some point change owner and perhaps be put to use, in which case any flaws may make them selves known.

Let me add a bit of my own experience to the debate, I've overhauled 67 and 68 models with good original cams and I've seen them worn out. But I once bough a Harris Bonnie (#35) and the nitrided exhaust cam was flat, so that can happen too with enough abuse. I believe one needs to start with good cams and lifters, properly lubricated, run them in while keeping the revs up, and make sure to keep a decent valve clearance. This is why I like to use 6 thou on the exhaust, as recommended by JoMo. I suspect to combat this very problem? The California climate would push the oil temps up quite a bit compared to Britain or indeed Scandinavia, that can't have helped.

Today's far better oils will protect much better though, and there's plenty of ZDDP in any 20w50 oil to help with that.

Food for thought, and we'll take it into consideration as we make our decision.

SR

Last edited by Stein Roger; 01/12/21 9:06 am.
Stein Roger #836423 01/12/21 10:33 am
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I wouldn’t use a Harris Bonneville as an example.


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Maybe, but it's L F Harris who make the replacement cams that most people are selling!

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Originally Posted by triton thrasher
I wouldn’t use a Harris Bonneville as an example.
Why not, Harris is the supplier of hardened cams today and I believe they get them from the same source as Triumph did?
Though it may have been different in the mid 80s.
Having said that, I've only worked on two "Harris" and both had severely worn gear boxes. Maybe they had issues.

SR

Stein Roger #836449 01/12/21 2:09 pm
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My '68 had good looking cams which I kept but I found the jiggler pin rusted up and its oilway clogged.
I was able to free up the pin and restore the oiling.
It seems they are often ignored at the peril of the cam.
I had the same questions at the time and there were conflicting opinions but someone said, "why toss a good cam" which made sense to me.


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(2) 1967 Triumph "Choppa"s
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Stein Roger #836462 01/12/21 5:06 pm
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All good thoughts and one I found in line with my thinking was Stein's comment on the 'next' owner of the bike who may put some miles on those cams. I know we're not building our bikes for the next owner but food for thought. And yes we do have better oils now but I'm not sure the modern 20/50's have any more ZDDP than the oils we used in the late '60's, of course I've been wrong before. One thing I have learned in later years is the proper procedure for breaking in new cams, live and learn...good luck. Mark R.

Stein Roger #837035 01/17/21 1:51 pm
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In my view the ZDDP scare was exaggerated anyway. It provides a last line of defense for when the oil film brakes down, which can happen in cam and tappet interfaces under certain conditions. In a well run in and properly used engine, this shouldn't happen. Maintaining adequate valve clearances, a decent oil regime and avoiding extended periods of idling comes into this. I too believe that a proper breaking in procedure is imperative, and we have decided to go with the cams we have.

Thanks to all for the input!

SR

Stein Roger #837079 01/17/21 5:50 pm
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Is 67 the last year of the full race intake and sport exhaust cams on the T120 and TR6?


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“But I don't want to go among mad people,” Alice remarked. “Oh, you can't help that,” said the Cat: “we're all mad here. I'm mad. You're mad.
Stein Roger #837120 01/17/21 10:44 pm
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3134's were used in the t120 until the end of it.
They gave 'em different numbers over the years but they were 3134 profiles.

NickL #837155 01/18/21 11:14 am
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I think you'll find that the exhaust cam was 70-4855 up 'til 1967, which was E3225 profile, with the sportier 70-4057 E3134 profile arriving from 1967 onwards, with changing numbers then depending on nitriding and such. I have the detail if anyone cares!

Stein Roger #837174 01/18/21 3:31 pm
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I rebuilt a '67 TR6C a few years ago and turned the bike into a desert sled. While others had been in the motor before, it didn't appear that the cases were ever split. I ended up reusing the cams and having the followers reground.

Living in MN, there aren't a lot of applicable vintage rides so I ran it mostly on trails pretty aggressively with friends that were on modern 4 stroke MX bikes. I soon discovered that my rings never seated because I foolishly used a semi synthetic lubricant to assemble the top end. When I tore it back down this winter, I discovered, with the help of this forum, that my exhaust cam had flat spots in it and it was likely due to the fact that the follower block was slightly rotated in the hole despite the locating bolt appearing aligned.

You sound far more adept than my story above, but I wanted to share my teardown findings. The intake cam and followers looked good, but still displayed more wear than when I rebuilt it. Neither follower block was far off (I later used a dial indicator with it bolted to my mill table to get it closer to center which was a 5-10 thou over 4" for me), but it still took on a lot of wear. This could have been attributed to the regrinding of my followers too, but I'm not knowledgeable in that. For me, I replaced everything with LF Harris. I wouldn't call myself experienced with Triumph's enough to offer a sound opinion, but this could be a data point for you.


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Originally Posted by Hillbilly bike
Is 67 the last year of the full race intake and sport exhaust cams on the T120 and TR6?
1967 was actually the first year of the E3134 profile used on the exhaust.
Road tests of the era showed that the earlier bikes were quicker off the line but the post 67-on Bonnies were quicker from around 50-60 mph and the terminal speed after the 1/4 mile was higher, even if the ETs were very similar. My main source is the re-prints of Cycle World I have, though other sources confirms this. I find the earlier cam combo better on a twisty road, more responsive in the mid-range. I convinced a friend to use a T140 exhaust cam (more or less identical to the early Bonnie/T110 cam) in his 68 Bonnie (to replace the worn original...) and he swore it went better at ALL speeds!

Odyssey, your opinion is certainly sound, your findings are valuable and we will certainly take them into consideration. There is plenty of evidence to support your findings, the exhausts cams on these bikes really were borderline. I always take great care to install the guide blocks correctly, but I've seen plenty of cam blocks out of line with no apparent untoward wear on cams or followers. The real answer seems to be in the lubrication and the cam material. The move to nitrided cams certainly put an end to the exhaust cam issues on these engines. However, oiling plays a big role too, as witnessed by Triumph's introduction of pressure fed oil to the followers. They also shortened the oil pick up in the sump to increase the residual oil level for 1968, to add to the oil fling. How effective that was can probably be argued, chances are that the inlet cam received all the added spray, the exhaust cam still living in the shadow...
Someone on this forum (NickL?) improved top end oiling on the exhaust by cutting an axial groove in the rocker shaft, effectively flooding the rocker box and pushrod tube with more oil. The reasoning must have been that the inlet cams were usually fine, but the exhaust cam enjoyed far less of the oil flung from the flywheel while actually doing slightly heavier work.
It reportedly worked well too, and I intend to use this mod while keeping the force feed.

SR

Stein Roger #837316 01/19/21 9:20 pm
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45 years ago I had 67 TR6C. I rebuilt the engine and noticed the exhaust cam had around .292 lift, the intake .312, neither cam looked worn .....It appeared the bottom end was never apart, but who knows what may have happened. And never checked serial numbers so it could have been a 66 model...
I went down to the local run down once thriving Triumph dealer and got a niced used 3134 type exhaust cam.
Oh, the ET ignition never caused any problems for a year before I changed the charging system and Ignition to have a bright headlight at night...


79 T140D, 96 900M Ducati ,61 A10 .On a bike you can out run the demons..
“But I don't want to go among mad people,” Alice remarked. “Oh, you can't help that,” said the Cat: “we're all mad here. I'm mad. You're mad.
Stein Roger #837359 01/20/21 7:58 am
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Hi, After 47 years in automotive dealerships, one for 12 years, one for 35 I can tell you this. Oil type makes a huge difference in cam wear & motor life. Easily doubling cam, bore life. Zinc is very important. High quality synthetics makes a huge difference also in cam & bore wear, especially in high heat areas.

Going from Chevron Delo oil to Pennzoil doubled if not tripled cam life. Castrol GTX 20/50 was one of the worst. Quaker State was one of the best. Warranty records from USA dealers bore this out.

On high quality chill cast cams with stellite faced rockers wear was not much problems no matter the oil, but good oils made these cams last 500000k+ miles, where poor oils would wear them in 100000 miles easily. That would be 5 times longer. I had faster wearing normal cam with hard cOhrome rockers. I got 350000 miles on original cam & rockers using pennzoil 15-40, then later on Shell Rotella 15-40. I sold car then working good.

They started removing zinc as it contaminates cat converters.

After zinc went down we had wear again. Synthetics cured that. They make Triumph wet clutch slip in less than 20 miles if used in primary case on later motors. Wet clutch approved synthetics are made.

So I feel a good modern oil is a smart choice with old cams. I'd get a very high zinc oil if available. Zinc is all over the place. You need to see spec sheet to know. More oil to cam is better, but high volume of poor oil will still allow lots of wear. Less quantity of good oil would wear less. High quantity of good oil is what we want when possible. Remove restrictor dowels & use low flow tappets is a good plan to me. I would never stop oil to tappets if possible though.

Triumph did lots of stuff later on like remove tappet oiling, primary chain oiler. Was this to make motor last longer or to save a few shillings??
Don


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Stein Roger #837368 01/20/21 11:24 am
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Just a gentle disagreement, the early exhaust cam and the T140 one have very similar lifts, but the latter is a much more modern ramp cam. I'm not surprised your friend's engine went better if his original cam was worn out anyway!

Stein Roger #837377 01/20/21 1:16 pm
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Somewhere between the US and the UK in the postal system is (I hope) a TriCor accessories booklet from 1967, showing what they offered for the stuff which Triumph shipped out to the east coast dealer hub in Towson, Baltimore.

One of the options was a revised set of cams - when it arrives, I'll see what details I can post. I think the valve timing is given. Interesting maybe to see how they compared to the 3134 profile standard ones.

Nick


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TinkererToo #837610 01/22/21 9:02 am
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Originally Posted by TinkererToo
Just a gentle disagreement, the early exhaust cam and the T140 one have very similar lifts, but the latter is a much more modern ramp cam. I'm not surprised your friend's engine went better if his original cam was worn out anyway!
I agree that the T140 cam differs in that it does incorporate a small ramp. It's somewhat effective too, reducing tappet noise. The T140 and TR7 does emit less of a racket than earlier twins, and along with ramps, the cam wheels were made to closer tolerances and a better finish, and were substantially heavier too. Hopwood thought the Triumph twins to be "horrible clatter boxes" but these changes went some way to reduce this.
To qualify my statement about cam wear, my friend's 68 exhaust cam wear wasn't bad at all, it merely showed signs of starting to wear, so wouldn't have impacted performance much. I rode the bike before and after, and thought it went well with either cam, but the T140 cam did give it some more low down and midrange. The claim that he didn't lose any top end was his though, not mine.
I did have a "Harris" Bonnie with a severely worn exhaust cam later. How that can have happened I can't say for sure but it was extremely dirty inside so my guess would be poor maintenance. Good, clean oil and regular valve clearance checks are vital.

SR


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