beer talk

worntorn said:

I don't have a Commando graph to post, but since it is only beer talk, have a look at the overlap and duration of this cam. Not sure if this thing will idle or even run, but will find out soon!

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Something with that sort of timing would work well at 4500 rpm on a long stroke engine like the JAP.It should be good enough between 3000 and 6000 rpm.
Most engines will run well with the intake lobe centre at 100 degrees ATDC,and the exhaust about 110 degrees BTDC.You could make more power if you retarded both cams 5 degrees,but it wouldn't be as much fun in the mid-range.

I'm wondering if the cam timing is set up to fire 50 degrees apart or 310 degrees/410 degrees apart.50 degrees could give trouble,even if you managed to get the ignition timing right.The ignition timing seems a ridiculous amout of advance at 0.700" BTDC.That's probably somewhere near 50 degrees advance.

The front cylinder fires 410 degrees after the rear. Total ignition timing advnce is 28 degrees. Not sure where the .70" ,50 degree is from? Maybe we are mixing J.A.P. with Vincent. No matter, it is only beer talk!

This bike will have a pazon ignition system, all of which are the wasted spark type. This had me concerned for a bit because of the early opening of the intake and the rear cylinder wasted spark occurring 30 atdc on intake stroke when at idle condition of 20 degrees btdc ignition firing.
Reports of blowback, rough idle etc on cammed up Harleys with wasted spark all come from companies selling new single fire replacement ignition products.,not from users. Harley has had wasted spark ignition for about 100 years, tho they are using some single fire now.
Any independant test showed zero difference between wasted spark and single fire on the dyno, and no difference in idle quality could be detected. This was with after market long duration big overlap cams.
Whatever has occurred on the rear intake stroke at 25 - 30 degrees after bdc , the contents of the cylinder are still in a non combustible condition.

Glen

worntorn said:

WZ507 said:

worntorn said:

I don't have a Commando graph to post, but since it is only beer talk, have a look at the overlap and duration of this cam. Not sure if this thing will idle or even run, but will find out soon!

Closing 115 degrees after bdc does not leave much for compression stroke.

Click to expand...

Although it looks scary big on the graph, it appears to only be ~ 270 deg duration at 1 mm lift and has a LSA of ~ 105 deg (milder than several of the Norton cam offerings), and therefore should be a nice performance cam. Given the opening/closing ramp design, I'd suspect you'd lash it at 0.25 mm, so IN closing at that lash would be ~ 90 deg ATDC, which is reasonable. Should idle well at 1200 rpm. It should speak well when it comes on the pipe!

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Well that is encouraging.
It is a MK 5 cam made specifically for big bore Vincents running a much modified head. The cam was designed by computer, specifically the cam development program used by Fritz Egli Jr when he
was lead Engineer on the Mercedes F1 team.
Punch in valve train data, the desired powerband , other engine specs and it spits out the perfect profile.

Glen

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Just to be clear in my own mind, when discussing/plotting Norton cam profiles on this forum we often speak in terms of lifter motion, not valve motion. But then sometimes we talk valve motion, so it is not always clear exactly which data we are viewing.

Right or wrong, I assumed your Vincent plot was for valve motion, but in hindsight the 11 mm (0.433") lift seems low for a large valve Vincent performance head. That said, I'm suspecting that the lift data in the plot might refer to motion at the follower not the valve? So what does the lift data in the plot refer to?

Since your plotted data appear to be taken at 0 lash and show well defined ramps, I suspect the data was take with a very light spring, i.e., only enough to assure mechanical contact. If that is the case, given the complex and somewhat springy nature of the Vincent valve train, fitting heavy springs will moderate the cam motion slightly, i.e., reducing duration and lift, thus softening the cam slightly.

Moderator - please delete this post as it somehow got posted twice

The Chap sounds like a self proclaimed guru .

if its not a Mouse in the intake ,
it may be a Sparrow

If this is not the case , it would have to be a Robin or a Finch , which could be more serious . As there are several species of Finch .

These would require a suitably qualified expert of their field , for satisfactory results .

If after takeing these steps , this proves NOT to be the case , you should reset the Vave Timing . :
1100ohv Racing ; io 44 ic 62 eo 65 ec 34 . Ign. 36 btdc .

std. 1323 dry sump ; 20 60 60 20 & 38 .

But seeing , if it ever were , it now aint . ( this sounds very conveniant :wink: ) as per usual , being Beer Talk . Its all hot air . Though in this case , I think you still owe me a BEER .

WZ507, that is lift at the valve, graph provided by Fritz Egli jr, not sure of his methods . I used the crossover point from the graph for timing and found very similar opening and closing points to those shown on the graph. This was with light springs in place for the timing setup, which also made it easy to check for valve/ piston safety space.

The total lift of the intake valve is. 433", which is quite high for a Vincent. Irving designed them with big valves and low lift for long life. The standard cam gives just. .315 " lift at the intake valve, while the
'Hot" Lightning cam, also called MK2 s gives .343". Some of Terry Prince's racing cams from years gone by went as high as. .50" lift, however the Mercedes F1 Cam Development Program showed that there was no advantage in lifting the big Vincent valve more than. 440, hence the Max lift at. 433 for these MK5 cams.

Glen

Again a other friend own's a Terry Prince RTV 1200 black widow...which is RED? when the timing cover was off i could see his wild cams, the carbs froth on tick over,,due to the massive over-lap. The bike is interesting, with it's one piece seat/ tank unit...in GRP ...not sure if it will like modern E fuel? ..i keep thinking i should buy it.as only 4 where made?

Those are likely mk 2 s or mk 4s. Supposedly the Egli Jr designed mk5 s he now offers as his top performance cam makes a lot more power than his earlier racecams, without lifting quite as high. Here are the mk 5 s and their radiused followers. The followers are lightened from the top which creates an oil galley to preoil the cam on startup.

Glen

Yep! that looks like them.
Are those cases TP ..i noticed he supports the spindles direct in the timing cover,,no support plate.
You have a lot to do there Glenn , ie no gears yet...getting the cams pressed onto the gears in the correct position for one? and then the large idler sizing...takes me back 30 years seeing this again...Tony Maughn did mine,,,god bless the man..he was a great lover of vincents, his sons are doing a great follow on job.

Probably the rtv 1200 cams look very similar but these mk 5 s are a new cam that did not exist until a/couple of years ago. These are a touch lower in lift but longer in duration, quite different in timing than any of his previous came.

I now have the Gears pressed on, timing marks made, and all else complete in the timing cases. Hopefully I have done it all correctly, but there is no manual for these particular components. Lots of email questions went to Terry, he answered all, so it should be OK.
Cases are from the Norton Manx builder, Andy Molnar. It uses regular steady plate timing spindle support.

Re after market Commando cams- is the split overlap method of valve timing commonly used for these?

Glen

do you Aussies really know how to make good piss.

Something stirred in my memory !!

About 10 years ago I visited the shop of an old mate who was complaining bitterly about English engineering quality.

I think he was working on a JAP Morgan and found the new cams had been made incorrectly.

I will try to talk to him this weekend and see if my memory is correct!

Or you could try this Ozzie

https://www.facebook.com/photo.php?fbid ... 030&type=1

He ain't bad on JAPs.

OMG! thats a beast!

johnm said:

Something stirred in my memory !!

About 10 years ago I visited the shop of an old mate who was complaining bitterly about English engineering quality.

I think he was working on a JAP Morgan and found the new cams had been made incorrectly.

I will try to talk to him this weekend and see if my memory is correct!

Or you could try this Ozzie

https://www.facebook.com/photo.php?fbid ... 030&type=1

He ain't bad on JAPs.

Click to expand...

OK. My memory was correct for once.

My NZ friend was working on a 1933 Morgan 1100 cc JAP 50 degree v twin water cooled engine.

He had newly made in England cams (this being at least ten years ago).

He found it impossible to get the cam timing correct. Bear in mind they had 50 and 60 degree v twin engines so check you have the correct cam for your engine.
But even allowing for this the cam timing was too far out. He thinks 26 degrees between cylinders but this was a long time ago so his memory could be wrong.

Sometimes with single carb v twins they do have different timing between cylinders but not as much as he found - more probably on race bikes than production bikes.

In the end he cut the cam in half with a wire cutter and made a new main shaft with two key ways. The car then ran fine.

He timed on cam centres but all the Morgan club information he had available to him at the time is with the car and the guy he did it for has since died. So unfortunatly he doesnt have the timing he used.

Hope this helps. Greg Summmerton is current on all this so maybe you could contact him.

John

Well you have got the right idea! a mouse/bird in the intake would produce the results...weak mix and rich mix..but alas no critters in there :!:
Thinking about this silly Mega rich/super lean issue between the cylinders can be down to very poorly ground cams..as no measure as corrected the fault.
As the builder was at a loss...and said..."it dosnt like brookland cams" whats that about? For pete's sake the cams will not produce weak/rich mixtures between cylinders?

When he left he said " Morgans never run the same on each cylinder's anyway" cause they dont! but i guess thats a pre-empt when he cannot get it right...Now waiting ..this is going to be interesting. But as the Guru would not allow me to peer over his shoulder [banned fom the garage that day]..when trying to fix it..then i may never know.