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Originally Posted by Hugh Jörgen
Originally Posted by henryanthony
Quote
-I tried to search something but the search algorithm in this site is almost useless. I mean; why if I write T140 LOBE CENTER do not show any thread about that but shows whatever?


Thanks

Hi Reverb, type the following in a Google search. The results may be helpful.

lobe center site:britbike.com
I would also add quotes around lobe center.

And double check spellings, my phone auto corrects to "love centre" laughing


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Hi; there is no any thread explaining or talking about assembled engine and which or where stop the rotations etc.

Hi Allan; no; I am moving the crank in the timing side with a socket and arm.
The inlet closing should be bigger but I obtained 40º so my interpretation of when to stop the rotation (forward) is wrong.
So, in this case, 1- I started to move the engine forward; the pistons go down; when the inlet valve is about to open and the rocker arm is stuck I stopped and obtained the 43º (the inlet camshaft is on another mark not at the factory mark)
2-continued moving forward, the rocker arms several more degrees stuck then free and the valve started to close, then stopped and obtained 40º.
May be I needed to continue the rotation; do ALL the 4T stages?

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Hi Reverb,

I’m not quite sure I understand this but where you say “ The inlet closing should be bigger but I obtained 40º so my interpretation of when to stop the rotation (forward) is wrong.”? Do you mean the degree numbers should be different than what your seeing at 0.040” lift?

I would advise that you use the rear wheel and work only from the drive side of the bike to do your measurements. This ensures a few things,
1) you have more control and can turn the engine much slower and be more accurate using the rear wheel (if we’re not going to be accurate, there’s not a lot of point in degreeing the cam, thus I don’t do it on all my engines, only those I want great things from or want to learn to tune a certain engine)
2) it saves a lot of either dashing to each side the bike or worse, leaning over and knocking your well setup dial gauge (this is another point, getting it setup so it gives a good repeatable result, might not be as hard on the triumph with vertical pushrods, but more of a fiddle with slanted pushrods on a bsa.
3) when you start going number blind, you will get less flustered working from the one side.


“ May be I needed to continue the rotation; do ALL the 4T stages?”
4T?= 4 timing?

There’s 2 points for each cam lobe, as you have a twin there is 8 timing marks, 4 for valve opening and 4 for valve closing.

Your dial gauge is in the right ball park for where an inlet valve should be closing.

Don’t be afraid to recheck TDC Incase this has slipped. And also do another rotation to verify your numbers.

As your probably aware, finding true TDC can only be done by finding x degrees before TDC, so say 0.050” down the bore from where you feel TDC is. Set that as zero. Then go past TDC and back down the bore 0.050” and bore the degrees travelled. You might find the crank has moved 8 degrees for example, keep the crank still and move the disc so it now reads 4 degrees on that timing mark. Then again take the crank back to 0’050” btdc, it should read 4°BTDC, then same 0.050” down the bore after TDC and it should read 4° ATDC.

Again, if you find your valve numbers are varying by a degree or
2 when you check it on a second pass, then do your measurements at 0.080” lift. You’ll get within 0.5° or less.

It all takes time, draw up a chart showing all 4 followers.

Last but not least, and sorry I didn’t notice it earlier.: rig up something my sophisticated than the long piece of wire. I like to use a long Allen screw with the cap drilled through so it will support a fine Allen key. If the screw feels loose, some PTFE tape around the thread will stop it rotating. It doesn’t take much of a knock with these things to completely
Thrown out your timings.


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[Linked Image]

An old picture now and done off the timing side, I subsequently do them off the primary as described and find it easier. [Linked Image]

I don’t rate these nylon discs much, you have to be really
Accurate cutting the centre hole. The aluminiums are better and lend you to make a proper means of securing it to the crank.


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I recently made an adapter to allow me to attach a degree wheel to the rotor nut without removing the primary cover. It is only held in place with a set screw, so is not designed to be used with a running motor, but should work to set ignition timing more accurately, and to check cam timing if you can attach a dial indicator to measure valve movement. Although I added flats on the outside after taking the photos, I think it would be best to rotate the motor using the rear wheel with the transmission in gear.

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

I have not yet used it. If anyone wants the drawings, I can post or email them after I refine them a bit. My mill is metric; hence the metric dimensions. I can also convert to decimal inches.

Tom

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Hi Allan; I tried to say that the inlet closing figure would be bigger than the opening one; hence I am saying that is wrong. (40º is less than 43)
With 4T I wanted to say the events (intake compression; power and exhaust) so if I started rotating the engine forward at the intake stroke (pistons go down) and the intake valve starts to open; I obtained those 43º; after at what point should I stop? I stopped when I saw (and feel the rocker arm) the valve started to close (and obtained those 40º) The fact is that is wrong. I still cannot get it where is the mistake; If not how many 360º the crankshaft would do?

Regarding small movements; at least with this later Triumph unit, I did not see that with the wheel would be better. Very fine tuned with the socket; you can move a fraction of a mm only touching the arm.
The TDC and the disc mark coincided in all the checks.

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Originally Posted by reverb
Hi Allan; I tried to say that the inlet closing figure would be bigger than the opening one; hence I am saying that is wrong. (40º is less than 43)
With 4T I wanted to say the events (intake compression; power and exhaust) so if I started rotating the engine forward at the intake stroke (pistons go down) and the intake valve starts to open; I obtained those 43º; after at what point should I stop? I stopped when I saw (and feel the rocker arm) the valve started to close (and obtained those 40º) The fact is that is wrong. I still cannot get it where is the mistake; If not how many 360º the crankshaft would do?

Regarding small movements; at least with this later Triumph unit, I did not see that with the wheel would be better. Very fine tuned with the socket; you can move a fraction of a mm only touching the arm.
The TDC and the disc mark coincided in all the checks.


Try removing the rockers and work straight off the top of the pushrod.

Also what are the book figures (better still if they are at 0.040" lift) for your cam? Is it a triumph cam? or a Johnson/Megacycle/SRM..... cam?

If I am reading you correctly, you are currently seeing an valve opening at 43D BTDC and closing at 40 ABDC, in short this will give a lobecentre position of 88.5D ATDC (D=degrees as I don't have the correct symbol on my works PC)

I'd check again straight off the top off the pushrod, find the stroke where the cam follower is running on the base circle and verifty your zero point on the dial gauge.

For comparison an A65 "Spitfire cam" would have an inlet lobe centre of 98.5D ATDC, (I mention this cam as the profile is preferred for different makes too).
At 88.5D you will make good bottom end to mid range power, it will still rev well in lower gears but under load it won't breath as well as it can do. Somewhere between 98 and 106 inlet Lobe centre will make good top end power, closer to 106 the better but you will loose some at the lower end and may even find a flat spot in the rev range (this is what I found with the spitfire cam when I was retarding it for more power, it went like a rocket up to about 4000-4500 rpm, after that it went like a rocket too, but inbetween was just flat!)

Am i right in saying the Triumph timing pinions have 3 keyways? this will give you plenty of wriggle room to get where you need to be.

Dont forget to do the exhaust side too!

If you have the time, a bag full of gaskets and the inclination you can learn quite a lot from playing and adjusting the cam timing to where you want it to be. The factory would have found an optimal to cover a wide scope of customer uses.
I don't have the time like I used to, I also don't have the same inclination to see how hard it can rev or how fast it will go.


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Hi; the inlet is a 7016 if I remember right; positioned in a new mark "C"; the exhaust is a 9989 at factory marks.
Exhaust opening and closing numbers were pretty bad so is like mentioned; my interpretation of the technique is wrong.
-I think, like mentioned before; that the problem resides in where I stop the rotation in relation to where I SHOULD stop actually (hence asking about the cycles of the engine)

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It doesn’t matter where you start and stop the cycle of the engine. As long as it’s moving in the forward direction and you find it lifts up to 0.040 from the zero value on the dti. Then you just mark the timing value off the disc and it’s relation to TDC or BDC .

It’s relation to TDC or BDC will tell you which stroke it is on. In this instance your over thinking it.

Being a bsa man I’m not familiar with the timing values from the book but if you have them I’d be happy to work out the correct LCA for you.


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Maybe I am miss interpreting this:
"With 4T I wanted to say the events (intake compression; power and exhaust) so if I started rotating the engine forward at the intake stroke (pistons go down) and the intake valve starts to open; I obtained those 43º; after at what point should I stop?"
Are you saying you are looking for the intake valve to open after TDC? The intake opens before TDC.
You should work with the lobe centre and not opening/closing angles. that way you do not have to worry about exact measurements of small lift.
Use the crank locking tool to set the degree wheel or measure the piston near the largest range of your dial indicator, less error induced.
If you do not have the cam opening/closing numbers, read the crank angles at half cam lift and calculate the lobe centre from that.
Otherwise for intake:
(BTDC + 180 + ABDC) / 2 - BTDC is the lobe centre ATDC
For exhaust:
(BBDC + 180 + ATDC) / 2 - ABDC is the lobe centre ABDC

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Originally Posted by DMadigan
For exhaust:
(BBDC + 180 + ATDC) / 2 - ABDC is the lobe centre ABDC

You mean:

(BBDC + 180 + ATDC) / 2 - BBDC is the lobe centre ABDC

Whilst I’ve tried to explain above, I admit I’m not Always the best at putting it into words.


If I get chance I’ll do a bit of a video, I have the head off one of my bikes at the moment. Though it’s freezing here at present and the new garage isn’t yet insulated. So if your lucky….


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Is wrong what I did because I obtained a smaller number with the closing of the inlet valve; that value should be bigger than the opening number and the other way around for the ex valve.

Hi DMadigan; I said that TDC is at 2 events; the intake and compression; so the technique involves put the crankshaft at TDC to starts all the process; so I did that and used the intake not the compression event (where both valves are closed) pistons go down.

I understand that formula but the point that I am trying to ask is at what point should I start (the event) and then after initiated the first rotation and take the first number (when start to open) for the inlet valve on the disc, I keep rotating forward to what point? As mentioned; I stopped when the inlet valve started to close (and the rocker arm stuck again)

Hi Allan; the thing is I am trying with the method with the engine assembled; like the title of this thread.

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Sorry, yes, BBDC
reverb, I presume you are finding TDC from the crank stop tool or the timing mark. I forget which cylinder that is for, timing side, I think. You need the timing disc on the crank. Once you set the disc for the timing mark, put in one spark plug and rotate forward until you get compression. The opposite cylinder will be on the intake/exhaust overlap. Check that cylinder's valve timing against the disc. Then you can check the opposite cylinder.

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Reverb, you can still do it with the head on, just remove the rocker shaft and rockers.


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Hi DMadigan; the twins go up and down at the same time; not like the triples.
By the way; the other day I tried to send a message about some measurements and distances of the center stand but could not.

Hi Allan; I do not want to remove the shafts due to many things; ones are the O rings; that I do not have more and I live about 25000km of the closer Brit shop.
I am still trying with all assembled.

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Originally Posted by reverb
Hi DMadigan; the twins go up and down at the same time; not like the triples.
By the way; the other day I tried to send a message about some measurements and distances of the center stand but could not.

Hi Allan; I do not want to remove the shafts due to many things; ones are the O rings; that I do not have more and I live about 25000km of the closer Brit shop.
I am still trying with all assembled.

Didn't know triumph used o'rings on rocker shafts??? anyway your call.

BSA made lift measurements with valve clearences set at 0.015" this would mean any rises on the cam and the quietening ramps would be largely ignored till a certain amount of lift is obtained.


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...the other day I tried with the method of unscrew the adjuster and put there a feeler gauge instead of feeling the rocker arms. I obtained the same numbers for lobe center: 87.5 for the inlet with the camshaft in a "C" mark and 88 for the ex with a 9989 at factory marks. For the ex I would obtained something like 55 and 34 to obtain 100.5...or so; you know that is in factory marks; ok is a T120 profile but 88? so still I assume that is bad technique.
To really see if the technique is wrong; next step is to remove the inlet wheel and put it on factory marks; then proceed again with these assembled engine methods.
Still did not do it because I prefer to make some kind of device to fit again the wheel without hit it.

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The only way you can be certain is to double check you timing marks aligned properly, (might take about 50+ rotations for all the marks to align again) then move to the next keyway position and make your timing checks again.

I know zilch about triumphs, so I don’t know if cam pinions changed over the years or not, but your method sounds fine and will get you about as good as you can get it. Did you increase the valve clearance to what the book specifies for checking timing? Is the dial gauge stand solid - won’t move/rock. And don’t forget the key ways are there so you can obtain the correct timing.


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...I have all the marks aligned; the new "C" mark could be odd but not the ex camshaft that is in the factory marks.
As mentioned; I did not removed the wheel due to I need to make kind of device to push in again on the camshaft (the later models do not have a thread in the wheel only 2 holes with threads for the extractor)
-Yes; as mentioned in previous comments, I used 0.040 of clearance for the valves that were checked.
Of course I could have the "C" mark wrong set but again; the ex on factory marks gives me 88º...
What I do not know is what are the numbers for the stock 7016 camshaft set in the factory marks.

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Are you using 0.040” valve clearance as well as checking lift at 0.040”?


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...valve clearance.
I am not checking TDC lift yet. I am trying with the lobe centers methods.

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Originally Posted by reverb
...valve clearance.
I am not checking TDC lift yet. I am trying with the lobe centers methods.


I am assuming that you were happy with your TDC? as you insist on checking the cams with your head and rockers fitted, you will need to increase the valve clearance over the standard setting, for BSA A65 this is 0.015" tappet clearance, for triumph it might be different. Once you have made these adjustments you can then proceed with checking the timing marks at the valve opening.

However, can you post a photo of how you are checking your TDC? as again with the head fitted, it doesn't make things as easy as it could be.

However, if you are using one of theseand putting your DTI in the end of it, then you can find true TDC, using the method against the wheel as I mentioned earlier.

You can probably use a solid plug in the hole, but I don't like to poke a fixed solid object against my pistons. If you are just using the gauge to tell you when the crank is at TDC then you can easily loose several degrees as the piston will rock over tdc.

Originally Posted by reverb
...
I am not checking TDC lift yet.

for all im concerned, lift at TDC means squat, the most it will help with is how close the valve is to the piston.


Do you have a buddy which you can rope in and help you with this?


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Hi Allan; no nobody around that know how to tune outside factory marks.
I have the Triumph tool to check the TDC at the rear of the engine and on the plug holes.
0.040 valve clearance is good to check on a Triumph and as mentioned I used 0.020 and the lobe centers were the same.

-I will remove the rocker boxes to put the DTI on top of the pushrod. I have special gaskets that I do not want to damage.

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...in the meantime; I removed the inlet wheel from the "C" mark and keyway; then fought a bit with the springs and engaged again but in the "B" mark (with the idler long dash); the factory marks.
Then; checked again the lobe centers with the method of feeling the rocker arms:

-The lobe center for the 7016 was 94.5º
-The lobe center for the 9989 was the same as the other times.

The VINTAGE BIKE MAG article about T140 timing mention lobe center 107º for the 7016
with an inlet opening at 40º; I had 35º BTDC. Closing at 74º; I had 44º

Next step is to remove the rocker boxes but I think that I do not have enough space to fit the clock over the pushrod due to the frame; so may be is useless to remove its.

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At the valve timings your seeing, the valve would be opened quite a way before the piston reaches TDC (looking down the plug hole) with it in the right position,again looking down the plug hole you should see the valve start to open just before it reaches TDC. Remember you won’t actually see the valve lift off the seat this way. Also the valves want to be roughly open the same amount as it nears TDC.

This isn’t a science, just a quick visual check whilst the head and rockers are all attached. But it will give you an idea if your timing measurements are out or not.

94.5° is about what the spitfire cam is using, it’s a good inlet setting.

Quote
The VINTAGE BIKE MAG article about T140 timing mention lobe center 107º for the 7016
with an inlet opening at 40º; I had 35º BTDC. Closing at 74º; I had 44º

If the timing alone was just out by 5° each side, then I would say that the timing is out. The fact it is out by 5° at one side and 30° at the other, it sounds like you might have a different cam. Even if your timing checks were way out. You are well out and sounds like you have a different cam than you believe you have, or your cam followers are ground/worn different. Check the other inlet and see that that is giving you the same readings. Don’t adjust the timing disc on the end of the crank.

I’d be happy with 94.5° LCA, but if you really want to achieve the 107° then you will have to try turning the cam pinion back a tooth after you have compared each timing mark. And check again.


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