Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board T140 not sure to do this or not

When you open the intake valve at 98 lobe centre instead of 107, you open it earlier. That's advancing a cam. To be thorough, take degree readings at 0.080" tappet lift on the opening and closing ramps. The true centre will be 1/2 way in between.
Using 020" lift is not as accurate and can be misleading (sometimes to about 5 degrees).

Got it.

Cheers,
Bill

Keep in mind that advancing intake cam timing will increase cylinder pressure at mid range speeds and increase the possibility of detonation...

...hello Pete R, I ll see what I can do.
Zombie, the 79 is better suited for the stroboscopic light; as I mentioned.

It works a treat, when the original timing was retarded. It works even more, and has little chance of detonation, if it's already a long duration cam.
The closing point on a standard T140 is 19 degrees later than a 650 with 3134 cam, so a lot of cylinder pressure is already being bled off to reduce torque. As A.G. Bell said in "4-Stroke Tuning"- "Retard the intake timing if you have too much wheel-spin coming out of the corners".

It would help if there are temporary timing marks for the other 2 keyways (one will become permanent). The one counter-clockwise from standard keyway will be 17 teeth away from original standard mark. The one clockwise from standard timing mark will be 16 teeth away. Clock wise mark used with nearest keyway should give 9.6 degrees advance.

So does anybody think it's worth doing or not

Valves and cams, yes. If you have the money. That thing will be better than new and probably last forever.

I am at a loss as to why keyways are changed vs. re-marking the gears.

I may be missing your point, but the choice of three keyways mean timing can be altered by a third of a pinion tooth.

Are you saying that the cam can be turned inside the gear, and the gear remain on the timing mark?

I also don't understand the "Third" of a tooth.

I'm used to Jap, and US bikes where the OEM marks just get you to OEM timing, and then you adjust off of those as reference only.

Oh wait... I do understand what you meant... Many times you end up too far advanced or retarded due to the location of the tooth. By quite a lot sometimes depending on tooth size.
Are all Triumph cams built with multiple keyways? or is this just certain sets or aftermarket cams?

I appreciate the input Triton. Thanks!

Some early pre-unit camwheels only had one keyway. Since then, they all have 3 to choose from 16-2/3 teeth apart.
When using alternate keyways, you will need your own non-standard timing mark, which will line up somewhere radially close to the keyway you use.
I've given the tooth counts for 4.8 degree advance and 9.6 degrees advance; as counted from the standard timing mark.

Now I understand. I also understand H.Tigers comment of a couple hour job now too.

It still sounds like a win/win for Triumph owners. Personally I would never pass up the chance to improve the engine using factory "freebies".

Thanks fellas!

Sounds like it's definitely worth doing even if it's a bit of a pain in the ass.Even just the inlet cam without changing the exhaust cam seems worthwhile. I'm OK with changing cam timing but since I only do it when I'm rebuilding a motor, I don't do it all the time and it takes me a bit longer than, say, Pete, who is very comfortable with the nuances of Triumph cam timing.

I tend to do it over and over, just to be sure it's right. When I button it up, I feel confident it will run right. I'll approach the owner with the idea, but he's into this bike about 3k so far so he may wait on it. I mean, we're doing damn near everything except stipping everything and powder coating things like the frame.

Front wheel with new disc imported from Australia. Really looks the part and should improve braking a little.I powder coated it and the caliper gold for that Italian look....


Cheers,
Bill

...so, the exhaust timing would be stock?
and in a T140E the valve timing still would be the same strange stock numbers or should change due this inlet camshaft timing change?
-About the keyways; is not possible to use the std marks and advance counting from that keways and pinion marks?
I do not know how to explain it.
Sorry, but Im a bit confused.

Thanks

What they are saying the problem is, IF you use the OEM keyway as your base setting, your teeth will not fall within the recommended timings.

One tooth will be to far, and the one next to it will not be far enough. So the factory provides separate keyways that are split in between teeth. You have to adjust, and make your own timing marks on the gear to compensate for the new gear position on the cam but that is the easiest way to gain torque I have heard for these bikes.

Look at it like this. You build a bike, and want to slow it down so your kid can ride it. You throw a set screw in the throttle that limits the amount of twist.

That's essentially what Triumph did. They lowered the torque by setting a goofy cam timing, and they left the good settings in the cam so you can use them if you decide to.

Zombie pun... No brainer.
The fellas posted up the best numbers to use a few posts back. 105*, and 104.5*. I believe these were OEM cams but re-read to be sure.

The T120 3134 intake cam sounds like the best street choice for use in your exhaust side, and they should be available in buckets full for fair prices.

...hello Zombie, thanks
I was referring to those 17 and 16 teeth mentioned by Pete R, if I could have the std as reference an add the other teeth to the next keyway then start counting those 17 or 16 teeth...may be a stupid question also the question about valves timing on the T140E if remains the same after all these changes; you know, I m a rider not a mechanic; I just rebuilt only a few of these engines in all these years and always used the stock timing marks; never tuned a bike.

--Also: what happens with this tuning and a fixed magneto like the Hunt put into a 79? Will kickback?

Now you are out of my comfort zone. I'm not sure I understand the question.

Let's take TDC as a base. The cam(s) will stay locked in that position, and you will pull off the cam gear, and replace it, and the key in the cam slot that will allow you to advance to the timings Pete suggested. I'm not sure which key you use as I have not done this on a Triumph yet but you can determine this by using the degree wheel, and matching the degrees specified to the valve opening distance.
BEFORE you change the timing you mark your NEW gear position as the NEW base line setting. You will be approx. 1/3rd tooth different on the cam. From there you count teeth or set up a degree wheel to match the degrees to the recommended.

Perhaps there is a step by step around that someone will recommend?

This is an easy process. It is all in matching the numbers, and they will be the same on every same engine.

Try Youtube, and search Cam Timing. Any engine will serve as an example to give you the "jist" of the idea.

Here's an easy one to follow. https://www.youtube.com/watch?v=-VwsbEg7Z4I

...I visualized that way only adding the teeth between the keyways in the count so in that way I do not confuse things having more timing marks; but may be that s not possible.
I mean; main question if I can use the std marks that pinions have so I count those 17 teeth + the distance (in teeth) from next key to this previous std key that have the factory marks...
may be is not possible.

Besides the opportunity of the three key ways, not all cam wheel key ways are broached exactly the same in production. Mind you they are pretty close, but more than the odd one is different enough to make a difference. With a stack of cam wheels one can juggle them around until you get the exact cam timing you are looking for.

Reverb... Ok, I get what you are asking.

I would have to say no because what you are proposing can get too confusing.
When I mark a cam gear for multiple timings I use a dremel tool, and one of their cut off wheels. The real thin fiber blades.

The OEM marks on a Triumph are dots, and one dash. The dash goes the same direction as the tooth so I would make sideways dashes on the teeth I wanted to line up.

You can do the same on the end of the cam(s). Mark them to know which key is OEM, key 1, and key 2.
I understand where you could get confused, and forget what is what.

On drag/street cars I would have two sets of timings besides the factory marks. Each one individual to itself so I knew what that timing mark meant.
Ie: dot/dot = factory
dot/dash = street
dot/dash, dash = track


Mr. Healy,
Thank you for that tip. Cam gears are cheap enough to pick up a stack of them (from different years I assume). Another pro tip in my folder.

...Zombie, that s a good procedure. Thanks

-regarding different cam pinions, in my 79 engine I have the ones with A B plus dots.
STD align A with B from the other pinion; How about the other B s? Are for other type of tuning?

That I don't know. One of the Triumph guys will.

Do you have the shop manual? I believe that will have the info.

I'm pretty sure it is a matter of shared gears like in the older models. In my case (1970) the same gear is used in the T120, and the T140. They use the dot/dash method to discern which timing mark is for which engine.

Someone will have that info for you.

Reverb, for the T140, the Inlet B dot is aligned with the dash ( or the lower of the two marks on the intermediate wheel ) and the Exhaust A dot is aligned with the single dot on the intermediate wheel.
The standard factory timing is the keyway in line with the timing marks on the cam wheels.(in most cases. It is always prudent to mark the keyway in use before dismantling. The duplication of marks on both T140 cam wheels are just for interchangeability reasons. Production expediency?)

...ok, I thought that may be a "hidden" tuning using the other way.

-another thing is in the T140 s that have bigger valves than earlier Triumphs is not correct to have "lower numbers" to get better flow? or that s occurs in engines like the TSS (more valves)?
but I do not know if I get it right...

Thanks

Valve size, and timing/duration kind of do, and kind of don't affect each other.
Size has to do with volume, and velocity, and timing/duration have more to do with pressure, and output power (torque).

You can kind of overlap one to the other, and make adjustments or compensate for weak points in one or the other but they are really two separate applications in engine design. Realistically valve duration is more closely related to engine stroke or piston travel, and timing is more closely related the desired purpose for the engine.
Lets say an engine used for a farm plow... You need low end torque. Same engine in a generator... High end torque...

Valve sizing is more about how much, and how fast you can move fuel, and air thru the engine at the desired cam settings/rpm range. Ideally the smallest size that moves the desired CFM of mix thru an engine is what you want. Small size equals higher velocity, equals more speed of flow.
Things happen very quickly inside an engine, and you need the mix (in/out) to keep up.