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Classic, Vintage & Veteran For Coventry and Meriden Models. Anything pre-Hinckley goes.

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Old 10-26-2012, 06:34 AM   #1 (permalink)
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T140v Cams.

So yeah, been trying to read/search as much as I can into this and it's a sea of information spread over everywhere, none of it being that definitive.

I currently have stock T140 cams and while the engine is stripped (having a re-bore, dynamic balancing etc) I want to make the most of the cams. I don't want to use any expensive cams and you can get e3134 profile ones for 65 brand new.

If I am to change my cams, I'll probably use them as they seem very well hyped!

Basically, I ride mostly on UK backroads but I also plan to do some long haul stuff to rallies in Germany and suchlike. When I do longer stuff I'll have my girlfriend on the back loaded up with camping gear as well. Day to day it'll be me and shorter twistier stuff.

I basically want to know if it's best to stay with stock (I assume not...), change the exhaust to 3134, inlet to 3134 or both to 3134?

I'm probably going to degree the engine properly as I'm building it to ensure perfect timing so not worried about that.

I'm having my tappets re-ground anyway as part of the overhaul as they are rather flat.

Cheers!
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Old 10-26-2012, 01:37 PM   #2 (permalink)
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I have half race exhaust cams

I have no idea about profiles or numbers but they definitely a fair bit quicker than standard. I fitted them 25 years ago +

The advice now is to fit the batter three piece bearings and when I do the dreaded sludge trap, I'll bung in a set
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Old 10-26-2012, 02:51 PM   #3 (permalink)
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Yeah, sludge trap is done and I am getting the 3 piece bearings.

So you are running just the exhaust and it's good, yeah?
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Old 10-26-2012, 03:51 PM   #4 (permalink)
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The standard T140 inlet cam is actually quite a 'hot' piece of kit. It is the Spitfire profile, and you won't get anything much better than that without going mad, ie: resorting to special valve springs, extra piston cutaways etc. The part number for the standard T140inlet cam should be 70-7016.

The exhaust cam, according to 'the book', ought to be 70-7017, which is a much milder cam (NB: this cam has at least one other number!). However, Triumph tended to fit whatever was available, and therefore some bikes from the blockade period and shortly afterwards ended up with much more exciting cams.

Assuming yours are the 'official' standard types, I'd say leave the inlet as it is and fit an E-3134 profile exhaust (the easiest version of this profile to obtain is 70-9989).

Use R followers in exhaust, std inlet. If you use a degree disc and dial gauge to get the ideal keyways for each cam, so much the better, but if you simply use the previous keyways and normal timing marks you should be ok (9 to one chance of getting the timing spot on and 9 to 1 chance of it being as far out as it can be yet still useable, and much higher chances of it being somewhere in between - which is how most Bonnies left the factory!)

If you fit an E3134 profile exhaust cam you'll almost certainly notice quite an improvement in performance generally. There are various explanations for why Triumph, in their wisdom, fitted such a mis-matched pair of cams as they did to the 750 twins - one of the least plausible, in my opinion, is that offered by Norman Hyde, ie: that they fitted a very soft exhaust cam deliberately to reduce the power, in order to improve the longevity of the timing side main bearing. Implausible because there are much more effective and simple ways to reduce the risk of main bearing failure, eg: (a) fit better main bearings, (b) fit lower compression pistons. So, as you're already fitting the best available timing side bearing, I wouldn't worry about the effect of using higher-performance cams. Dave's 'half race' cams are probably Norman Hyde supplied E-3134s (only saying that because that is how NH describe them) - but fitting an E-3134 INLET cam to a T140 would be a backward step, performance-wise.
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Old 10-26-2012, 07:25 PM   #5 (permalink)
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Cheers John A! That's awesome.

Yeah, the numbers you gave are indeed what I have currently. I actually got my 70-9989 through the post today! Sounds like I made the right decision anyway.

Surely if you set it all with dials it doesn't matter what keyway you use? What difference does it make?

What difference is there between the "R" tappets and normal? When I removed them one pair have oil holes in and one pair are solid. I guess the difference is the radius? I have searched for this on numerous forums, I'm really struggling to find definitive answers!
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Old 10-27-2012, 06:07 AM   #6 (permalink)
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The 'R' followers have a larger radius (1 1/8") than the standard followers (3/4"). This affects the rate of lift. The inlet followers have hole, to reduce weight. The exhaust followers couldn't have holes due to the oilway that goes down to the small hole in the face of the stellite tip - so the exhaust follwers were lightened by means of the pair of semicircular cutouts on thier side faces. The shafts of genuine followers also had reduced diameter sections, partly to reduce weight and also to improve lubrication: some modern pattern followers don't have this feature and are probably best avoided.

The reason for there being 3 keyways is to enable fine tuning of the valve timing. This is only possible on engines with seperate inlet and exhaust cams (unlike Norton & BSA twins etc, on which the inlet & exhaust timing was unadjustable due to all being governed by a single camshaft). Each of the 3 keyways is 120 degrees apart, but the number of teeth on the camshaft pinion is not divisible by 120 (or 3), meaning that, in relation to the teeth, each keyway will give a small degree of difference in terms of where the cams are in relation to the crank. It is hard to explain without diagrams but I'm not aware of any on the forum I can point you to (Mr Pete knows far more about this subject, and has a different method too - maybe you can search his posts?)

Basically, to move a cam's timing (ie: position in relation to the crank) by a whole tooth would equate to about 15 degrees - ie: a lot. But if you use the keyways, that approx 15 degrees is split into approx 5 degrees per keyway. To set the cams absolutley by the book timing-wise, you need a degree disc on the end of the crank and a dial gauge in contact with either a cam follower or a rocker or a valve spring collar - plus, of course, all the correct setting figures. It takes quite a bit of time to set them as near to spot-on as possible, and therefore this was not done at the factory on normal production bikes - hence one reason for the variation in performance of these bikes.

It can make a very noticeable difference. I did this on my T160 years ago. It took hours (6 cam lobes to deal with instead of 4!) but I got it within a degree or two over each camshaft and it ran like a Swiss watch. I didn't bother when rebuilding my TR7 this year, partly due to the fact that I no longer have a dial gauge and I wasn't 100% confident in the relaibility of the setting info I could find, and also due to impatience to get it back together! I took my chances and used the same keyway the old cam was on, and the standard timing marks, and it is fine. I hope you marked the keyway your old cam was on? If not, you may have no choice but to use the degree disc/dial gauge method.

Like I say, there's a one in 9 chance of ending up with it best or worst, and much more chance of something in between. Bear in mind that even worst isn't 'wrong', its just as far from ideal as you can get before it becomes wrong, if you see what I mean!

Hope this is of some help.

Last edited by JohnA; 10-27-2012 at 06:13 AM. Reason: Add info re. follower shafts.
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Old 10-27-2012, 07:48 AM   #7 (permalink)
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Yeah that is awesome! Cheers! I'll definitely use DTIs to set it. I used to work in a massive machine shop so getting it right is in my blood I know a man with all the gear and a fair bit of Triumph knowledge too, he should give me a hand.

So to use the T140 inlet cam I should have the followers ground to 3/4" and the 70-9989 I should grind the followers to 1 1/8"? If so, I'll instruct the machinist at once
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Old 10-27-2012, 07:52 AM   #8 (permalink)
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Oh also, yeah it makes sense regarding the keyways. Never actually counted the teeth or worked it out. Being a bit dense
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Old 10-27-2012, 12:01 PM   #9 (permalink)
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My half race cam was from AngloBike, who used to make a lot of stuff, but could well have bought in the cams.

It was an exchange system, so they may have reground them ( or at least had a workshop do it as I don't remember any fabrication/engineering at the place)
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Old 10-28-2012, 01:10 AM   #10 (permalink)
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You shouldn't need to re-grind intake tappets if they look OK.Just fit them back on theirsame lobes and facing the same direction.If you can't do that they need to be re-ground and re-bedded.
Just change the intake cam timing to somewhere close to 47/67 (100 degree lobe centre),instead of the more normal 40/74 (107 degree lobe centre) timing.It will go better at any speed.

You will need to re-grind exhaust tappets,because they will be running on new lobes.They are probably already "R" radius.You will need to coat the cam lobes and tappets with cam-lube,and run the engine at no less than 2000 rpm for the 1st 20 minutes.That means avoid any slow cranking of the engine prior to start up.
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