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#849696 05/23/21 1:05 am
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Picked up a couple of Harmon and Collins b range Triumph cams recently. They are stamped 6534 which I have found is a .365 lift and 270 degree grind. What I have measured is more like .326 lift which is what their 7054 cam was(is). Either way, I'm going to try them and see what happens. They have a big fat profile like T140 cams so maybe good for some top end.
Anyway, they are welded and reground as was a pretty common practice at one time. They look nice, not been used. So, anybody know if these were typically hardened when they were made? If not, think it may be possible to have them nitrided like I have done to my cranks?
Thanks in advance to all the historians and metallurgists.

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Mike Baker #849727 05/23/21 11:30 am
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I had Web Cams weld and face harden cams for my double engine bike a few years ago. I believe it was/is common practice to use a hard overlay...but I cannot say for sure.
Most Triumph performance cams are set up around 105 degrees lobe centers, intake and exhaust.


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
1 member likes this: Mark Parker
Mike Baker #849754 05/23/21 6:51 pm
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#6534 are the H&C #6, street, track, scrambles intake op/cl 30-60, exh. op/cl 60-30 but I don't have lift figures. 7054 was their low torque, desert, scrambles track cam 35-65 65-35 op/cl figures and lower lift. I have a set of 7054's if you want lift figures measured.

I have ridden a Rickman TR6 with the 7054, Chantland 750 and Mik VM 34mm carb...pulled nice every where but ran out of breath early, great in the desert but probably the stock 3134's would have been as good or better all around for that bike.

The 7054's profile would never be confused for big fat profile of T140 inlet but like 3134's so your cam might be a nice all around street type cam and I don't think I'd be worried about the hardweld needing nitriding but think I'd call my nitrider just to see, cams aren't cheap anymore...your cam listed for about $50.00 back in the day I believe.

Above specs from first edition 1968 H&C book...

Mike Baker #849827 05/24/21 10:34 am
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Really not sure what these are. I suspect they were mis marked. They measure out to .326" lift when subtracting the base circle from the big measurement and as said, they appear to have a long duration profile. If you don't mind measuring yours, MTT, I'd appreciate it.

Mike Baker #849852 05/24/21 3:25 pm
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Mike, my 7054's, measuring as you did, gives me .320" lobe lift but I have found that this method of measuring isn't always accurate. I recently measured my MAP 1066's which are listed as .355" cam lift and was disappointed to find they measured less, can't remember how much less but enough to be concerned since .001"-.002" wouldn't bother me much. I then chucked them up in the lathe and using a dial indicator found them to be plus or minus .001"-.002" between 4 cam shafts...8 lobes of the .355" figure. So I don't go by easy check method any more.

I'll see if I can include a picture later of the 7054, T140 inlet and 3134 side by side if you'd like. The 7054's lobe looks pretty decent but when beside T140 inlet then not so radical. When you say the 6534's were supposedly .365" lift, do you mean cam lift or valve lift?...sounds like a lot of cam lift for that spec cams intended purpose especially for H&C and the era...just an opinion of course. Mark

Mike Baker #849856 05/24/21 4:00 pm
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Ok, I found a set of TT #6 cams in my collection but have no idea where I came up with that designation as there are no markings on the cams. The lobes are indeed rather impressive when compared to the H&C 7054's which are clearly marked on the shaft as such. Using the easy lobe lift measuring method I get .340" average and I had written .380" valve lift on the bag they were in. The Johnson cams #6 appears similar and was listed for tight TT course, scrambles but not good at high rpm...my opinion without knowing the duration etc. of what I find or think what #6's were intended for, is that they were intended to have short duration and high lift for good midrange scrambles type riding or torquey street bike maybe? This is just where my mind has cataloged this cam since I don't have any other info to go by without digging. Though looking at the #6's profile would make one think there is more than 270* duration there. Mark

Mike Baker #849865 05/24/21 5:05 pm
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Effective duration is seat to seat and not the long clearance take up ramps on some cams.
By most standards the Sifton 390 is fairly mild is very similar to the old Jomo#15 but with quicker lift and less duration...
It's not always practical to make comparisons..But on my LSR 650 Triumph on a Superflow dyno, it makes a peak of 46 ft lbs of torque @ 5100 rpm and at the HP peak @ 7050 rpm it still has 40 ft lbs of torque..This very wide power band should be ideal for vintage road racing with a four speed gearbox...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Mike Baker #849944 05/25/21 10:39 am
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Thanks for measuring MTT. Measuring a 3134 seems to work in that if base circle is subtracted from height, it works out to very close to factory lift specs. But I can see where that may not hold true for everything.
These cams were cheap and I'm a sucker for any hot rod part that doesn't come with a hot rod part price. And I'm always interested to know what can be gained or lost with them. Having the Hall boys nearby with their dyno and their similar curiosity makes it easy, relatively.

1 member likes this: Big Al in York
Mike Baker #849992 05/25/21 8:46 pm
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Mike, no explanation needed, I'd have probably bought them also...it's an affliction some have. I'll continue to do the easy lift check also but if I see a big discrepancy then I'll chuck them up and measure. Different opening and closing ramps may be the difference. Mark


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