I use MC cams on everything I build, and have yet for one to line up perfectly (or even closely) with those marks. If you don't degree them in now, you will be doing it later. Tony, is really the expert on this, since he has tuned them on his dyno, and I'm sure he'll chime in soon I followed his advice on timing the last set of MC cams (slightly retard exhaust valves opening, from MC specs), and it did seem to yield better power.
Cheers, Dan.

 

Thanks! Is there a method in which a dial indicator is not required? I'll buy a degree wheel.

 

Thanks! Is there a method in which a dial indicator is not required? I'll buy a degree wheel.

You'll need a degree wheel ,but a dial gauge isn't necessary.
To get lobe centres right,it's best to take measurements at 0.080" lift or more.One degree is almost 0.004" lift when the valve is lifted 0.080"-0.200".If you can measure within 0.001" with a feeler gauge,your measurements will be accurate within 1/4 degree.A full tooth on the camwheel (14.8 degrees) will change valve-lift by about 0.055".
Measurements taken at less lift,especially below 0.040",are next to useless and more inaccurate.
Try the standard keyways and timing marks first.Fit the head and rocker boxes,and see that the engine turns over without crashing valves into pistons.Adjust all the valve clearances to 2-1/2 turns of the adjuster screw;the exact clearance is not critical.
Then rotate the crank and note when a rocker arm just becomes tight as the valve is opening.You could use a 0.003" feeler gauge (or any thickness) between the adjuster screw and valve,as long as you use the same gauge to measure when the valve is closing.Rotate the engine further until the rocker arm just becomes free as the valve is closing.THE LOBE CENTRE WILL BE 1/2-WAY BETWEEN THE POINTS YOU JUST MEASURED ON THE DEGREE WHEEL.
Check every valve for timing.You can only make adjustments in 4.8 degree increments,by using an alternative keyway.That means you should be able to get the timing you want +/- 2.4 degrees.

 

Gotta have a dial indicator to do it right. It is not that difficult once you get it down. But you should check all possible combinations.

And don't forget to clay the pistons....

 

I have been thinking for awhile now on the hot rod motor that is going to go in my bike on how to make adjustable timing gears and I think I have it figured out. I'm either going to make my own hubs or cut down a stock cam gear and make a hub out of it, but the gear will end up bolting to the hub with three bolts with slotted holes so you actually adjust it the way do do adjustable cam sprockets on a jap bike or a belt drive set up on a car, that way you can put cam timing exactly where you want it instead of having to rely on the key ways and hoping it gets it right.

 

Lindy,Funny that you mention this as I have been doing a lot of reading and searching on Triumph cams (mostly for drag racing ) and I found someone on the net that had done this variable adjustment just as you described -seems quite reasonable and an easy way to do it .
Cheers R

 

We use two separate dial indicators, one on the in's, and one the out's, and a good large degree wheel.
The settings that Mega cycle print out are ok but some times the cams get ground in a way that make it impossible to get the lobe centers correct, we had a set of 510/65's we did yesterday that we could only get 100.5 on intake and 101.5 on the exhaust, most people shoot for closer to 106.
Sometimes it is necessary to do a custom offset keyway grind to get them right on the money for a race motor, but a street motor is more forgiving on the lobe centers.
often takes 4 hours to get them on the money and every different set of cam wheels is a little bit different and the three keyway slots are 2 degrees different.

 

keyway slots

I know this is nit picky but the SLOT is the keyway, and the key is just... well, the key! Offset or not!
Robbie

 

A cam is ground and it is done. You cannot change the lobes, you can't start grinding off metal or adding metal (unless you are a genius like Bert Monroe or Clem Johnson). You are at the mercy of the cam grinder when it comes to the keyways on the wheels. Unless you add keyways to the wheels (which I have seen done) or as Tony says, offset you keyway in the cam, you are gonna get certain openings and closings with each keyway in the wheel. In addition to manipulating the wheels you can go up and down a tooth on the wheel, but that is it. And it is not just a matter of cutting in new keyways, you must know where to put them or you are pissing in the wind.

Don't get all up in arms when I say this next part, cause it is not as revolutionary as it seems, but...the opening and closings don't matter. They matter and it is great if you can get them to come in within a degree or two of the suggested ones, but I have seen cams where the openings and closing look RADICALLY different than the card provided. At this point you have to look at the lobe centers.

If you get all the keyways and up and down a key stuff mapped out and you still cannot get the openings and closings that are recommended by the manufacturer's card, then you have to rely on lobe centers. Subtract the opening from the closing and then add 180, then divide by two.

You still have to map out the keyways and teeth to properly degree a set of cams, but if you look at the lobe centers then you will get a lot closer to the manufacturer's spec. Typically if you look at lobe centers, then you will be okay, but the most important part of the cycle is the opening of the intake cam and the closing of the exhaust cam. If these two numbers are as close to the manufacturer's spec as you can get then you will be okay.

I have degreed a BUNCH of cams in ten years of business and only one set of cams I got from Web Cam in Riverside gave me a choice of where I wanted to be on my openings and closings and lobe centers. That is the stock keyways in the wheels could have been "right" in two different positions. You are going to find when you degree your cams that 95% of the time you are gonna get ONE place where you need to be.

Also remember you will want the intake to lead the exhaust that is the intake cam lobe center should be less than or equal to the exhaust cam. Big wide differences between lobe centers are typically for high mid- to higher end power, closer lobe centers are for quicker and torquier motors.

Did we forget anything?

 

Hope this isnt going to sound like an argument because I think were saying the same thing, but opening and closing are the most important ( intake closing being the more important) lobe centers are just a reference we can have two cams with the same lobe centers and different opening and closing numbers , ramp rates etc... if a motor runs better its not because you change lobe centers its because you have changed opening and closing numbers, over lap etc...

And I couldnt agree with you more I have seen cams grossly different than manufacture specs. One of the things me and my father have considered was just building our own cams, you could do the lobes yourself on a CNC and weld them to the shaft similar to the way they do S&S Sportster pro stock cams, that way you can make them exact.

 

^^^^^why re invent the wheel^^^^^ ...
go with Tony on this...this is what he does....
Tony, quick question about the dial indicators.....do you take the readings directly off the lifters/tappets or do you have the top buttoned up and take the readings off the rockers? If rockers, do you take out all the adjustment?

 

in cam timing there are many things important, obviously the open and close points are important and they are very related to the lobe centers. Both Mega Cycle and Johnson Cams have different ways they want their cams set up, we usually end up doing a mixture of our way and their way. But, if you follow their instructions exactly you will be fine.

We use the 2 dial indicators that are set on top of the jugs with a set of push rods in the cam followers.
My full time engine builder at the shop is Bob Donabedian, he is a 76 year old ex nationally ranked flattrack team owner and builder from the 60's through the 80's, we often argue about the details but in the end he builds a damn fast race motor.

In my opinion too many Triumphs are built for max power and they end up being no fun to ride on the street, many times with a set of race cams nothing happens until 4K RPM, not many people get to ride around in town at 4-6K RPM.
The 510/05 and 510/15 are ok, the 510/65's are so so, but the 510/01 and 75 don't make a good street motor. Then when you get above .4 lift you get into crank clearance issues.

As for me personally, I still like a good old set of stock 1969 Triumph cams and plenty of low RPM torque for a good street Triumph.

 

Damn. Folks should be charged a fee to read this! Holy Shit! Looks like this is on my to-do list now. Thanks for your information!

 

Please post the link!!

 

Well while not the original set I saw, here is a set of adjustable triumph cam gears from megacycle . Pretty easy to machine up a pair,if you have a good machinist.
Cheers R

 

fouraces re "the link" ,Now thats the thing ,because I wasnt really looking for that modification -I just noted in the ol brain that it was clever,I moved on and have no idea where it was that I saw it.(been off work post surgery, so I have surfed the net a real lot these past few weeks) .
Cheers R

 

This is fun..
it's obvious there are many different ways to set up cam timing, and you can make the engine run ok by just lining up the factory marks on the cam wheels. you can make it run differently by adjusting the opening and closing points (AKA lobe centers). usually the centers have more low RPM power with the centers around 100 or so and higher RPM power at about 106. The centers, lift, duration (if you use stock or R followers) determines at what RPM the motor will make the most power (a combo of torque and H/P).
I believe cam timing is just like religion and politics, everybody has their own opinion.
Many times the flat trackers would use different centers on the short tracks than on the mile tracks. it's up to you what you want it to run like.
There is so many other things that need to be "blueprinted" into the package, the cams have to match the compression which needs to go with the carbs and ignition settings which need to jive with the gearing and then you may stumble on to the magic set up that goes with the way you want to ride.
Take all the advice you can get and make your own decision on what to do, if it doesn't work out, do it a again a different way and then throw your opinion on here for us to ponder over.
I learn a lot from these threads, keep it up.

 

...so, what s the advantage for a normal rider? I mean, enhance the power in what % regarding factory set up?

I think Triumph engines are better in low and mid range if you want to keep the engine without tearing apart every few weeks or months so, between 90 and 130 kms/h is possibly the best range to take the road on an old Triumph, depend on the model and year. What are the increase in speed in that range if some body do all that work, again and again? Is perceptible for the rider?(bear in mind that I talk about the "take the road guy" not a bar hopper or a track rider) Is too good the increment?
Is not better go the easy way and get a 750cc? you know, more cc, short and better conrods, better bearings (late ones), valves, etc, lot of things that you had found on early factory tuned bonnies; you can also put a E3134 on them...

thanks for a fair response

 

I'm with Reverb on this..
I get to test ride a lot of bikes here at the shop, many are built with 750 kit,big ass cams and other high performance improvements, some are fast others just make noise, BUT..
One of the best running bikes I ever rode was a completly stock restored 66 Bonneville that was done by Don Hutchinson's shop back east, we fixed an electrical issue for him, he told me the bike was 100% stock .020 over pistons and was just set up right, that bike would lift the wheel in second gear. It looked and ran better than 99% of the bike I test ride.
Can't beat the 3134 cams..but the number 3134 was used as a casting blank and the actual part number for the 1969 T120 cams is something like E6989

 

Nice, that's exactly what I'm building, I haven't made much progress/effort as of late....Im so surprised that as long as triumph have been raced that this type of set up hasn't been more widely used.

 

those are neat, but that kinda negates the ol' drilled out cam gears to lighten up the valve train.
I wonder how much more they weigh than the stock gears?

it sure would be a lot easier to dial in a set of cams.

 

I know this is aimed at Ducati engines with 2 valve heads,but it gives you some idea of what to expect if you use non-standard cam timing,or cam timing that wasn't recommended by the cam grinder.http://www.bikeboy.org/camtime2v.html
He's not shy about advancing the exhaust cam to improve mid-range.I don't use more than 110 degree lobe centre on a Triumph exhaust. About 100 degrees,give or take a few,works OK on the intake.
Standard camwheels can still get you within 2.4 degrees of the timing you want,without filing keyways or keys.

Heavy camwheels will make more power,just like heavy flywheels.Slower to initially accelerate,but more power when you get there.Didn't Johnny Allen use a 10lb heavier crank in 1956?

 

Yeah,105 lobe center usually works ok.
I believe all the Triumph LSR back then used heavy flywheels.I do know in automotive engines a heavier flywheel is said to reduce high speed harmonics from steady wide open throttle racing.
The difference between a good running engine and a great running engine using the same parts is detail...Better ring seal,better valve grind without recessed valves and tighter tighter quench .Sometimes the engine builder does this and sometimes the factory tolerances stack up better....
I agree with Torch that a well sorted stock engine can be the best for street use