Camshaft

[rec409]

Yeash thats alot off,, no wonder we have such problems with the twins geartrain,,,, Sure hope you can get a solution to this mess... Keep us posted, and thank yous o much for your efforts..

[SHIPCHIEF]

BUMP!!
I was thinking that Indian cam lobes could be correctly positioned on a local, undrilled steel shaft, and furnace brazed on. Then structural integrity and cam timing would be assured. Just the last lobe needs to be pinned on for the twin, the fuel pump cam.
My first choice is still John's cam. I could go $300.

[XYZER]

I have 2 6/1's. One has a noisy intake and can not be timed correctly to the crank. The intake valve opens early or late and won't start late. It is off maybe 4 degrees. It also has the typical air intake noise. The intake is almost as loud as the exhaust. My other 6/1 is timed spot on and has a quiet intake. Just runs smoother. Someday I will pull both cams and get my bad one ground to match the good one. I am thinking it would be easier to do if I have a master or a known good cam. 

[Crofter]

XYZER, I see from photos of my cam that the injection pump lobe has much greater duration than the valve lobes: I wonder if there could have been a screwup and a wrong one installed for your intake?

[XYZER]

Frank,
I have never had them side by side to compare. The bad cam could have several things wrong. The gear could be off or the intake lobe could be off. I never checked the exhaust.  I don't believe the injection pump lobe was swapped. I believe they did a typical throw the lobe on the get er close and drill it and pin it. If there fixture is a little sloppy they will play hell getting all the lobes and gear to stay at there correct position in relation to each other while they drill and taper pin it. If I had the cam specifications I would grind to that but those numbers are a bit unknown. I am happy with the way the good cam works (much quieter) and one of these days I'm going to talk to a cam shop and see if he can grind my bad cam using my good cam as a master. Many people with Listeroids have complained of noisey intakes and we used an intake silencer to hide the problem. It might even be caused by the timing gear on the crank........   

[Crofter]

Yes, if the crank gear were off a fraction in placement you would have at best a compromise  for valve timing. Also with the injector pump; ff the camshaft timing is off a bit you can shim the pump to get the correct initial spill timing in degrees but the map of the fuel delivery could vary hugely because of a variation in where the plunger contacts the lobe.

It is too bad regulations dont bode well for a big number of future sales as that cam and valve train would be worth a good rework. It is a shame because it is such a simple engine to work on. Just a bit more attention to detail would make a big difference in its predictability.

[Crofter]

Jens, does it appear the two holes in the lobe are not 180 Deg. apart or is the hole in the shaft off center?

[mobile_bob]

they are all off center, and as such shouldn't be a problem so long as they aren't off center a bunch

the reason they are off center is to assure that if the lobe is removed for whatever reason it can easily be put
back in the correct location and not 180degree's out.

i think the biggest problem is they beat the living shit out of the taper pin and in doing so set up stress risers which lead to early failure

bob g

[wormshoe]

Hi Jens !

I think what Bob is saying is that the holes are deliberately off center so that the lobe can only be mounted in the correct orientation....only one way.  It's not the pin that is being discussed, but rather how and under what circumstances the pin holds everything together.

And yes, the pin probably had the crap beaten out of it when it was installed originally. Accurately indexing the lobe to the shaft, the drilling of the holes and the general assembly techniques employed by the factory certainly leave a lot to be desired. Is it any wonder that the camshafts (in some cases) are hindering performance or at the very least are failing prematurely ?

Have a good day sir.


wormshoe

[mobile_bob]

Jens

the reason i said they are slightly offset is it is incredibly easy to screw up an drive a pin in 180 out if it is perfectly aligned.

not so easy for someone that is experienced with tapered pins, but very easy for someone that has never used on before.

case in point, i have heard of parts being broken because the installer didn't understand the taper system, and tried to assemble
without having the proper orientation, this only happened because the thing could be assembled 180 degree's out of place.

bob g

[Crofter]

Is there some conjecture slipping into the picture?  Can we verify that the holes in the lobes and/or the shaft deliberately  oriented off center? (They should have to be so in both parts) This seems like a very difficult cure of the remote possibility of  putting the lobe on 180 off, though I have seen it done on timing mechanisms on hay baler components. I wonder if it is merely sloppy unintentional dull drill dull operator circumstance. I know that it is very difficult to get a true hole perfectly centered and even more difficult to get a  true and consistent hole deliberately off centered.

Do new factory cam lobes come pre drilled? do shafts come predrilled or do the holes get drilled into the shaft at assembly time? Lots of questions!

[rcavictim]

India is in he news his week because they are not ready to host the world for their olympic games, or whatever the hell games it is, even though they have been preparing the olympic facilities for many years.  Cement that needs 6 months to cure for safe strength in structures that will support the expected visitors is still being poured this week.  Apparently the army of workers who are not being paid minimum wages and have to go to the bathroom anywhere they can find, maybe in that wet cement?, and who are working without shoes has had the heat turned up on them to get the place finished.  They have less than a week now before the games are suppossed to begin.  I suspect they will be late and their party a disaster.  The reason will be given that work could not proceed because a sacred cow was on the road, in the way.

We in the west may be expecting way too much of this pathetic lot if we think they can put a pin in a camshaft correctly.

[cgwymp]

No, I can not believe that off center hole positioning has been done on purpose in this case. It makes no sense (and weakens the camshaft).

How does it weaken the cam? Seems like if anything, it would be stronger because if you do not drill directly through the exact diameter of the shaft, you're removing less metal -- i.e. by drilling directly on the diameter (on-centre) you'd be removing the most material, and less as you get farther off-centre.

If I had to guess, I'd guess the lobes are placed on the shaft, indexed (to some extent ;-), then both drilled simultaneously. If the hole isn't perfectly centered, then you get the extra benefit of not being able to reinstall it out of phase later.

And I'd also tend to think that if drilling it off centre does weaken it and it makes enough difference to cause failure, then the material was inadequate or the shaft too small to begin with. It shouldn't be engineered that close to the edge (pardon the pun).

[Crofter]

Tapered pin in a straight hole? what happened to the taper reamer operation prior to driving the pin. JohnF apparently has seen unassembled cam lobes, maybe he can vouch for whether or not the holes are 180 Deg. apart and whether they are the same diameter side to side. Can you order a bare cam shaft and if so does it have the holes drilled?

[JohnF]

First:  The Indians are NOT bright enough to drill holes slightly off centre.  It is caused purely by poor work habits - dull drills, not prepping the round surface before drilling. 

The cams come with the holes pre-drilled and the ones I saw "looked" to be drilled correctly, but I wasn't measuring that as we do not intend to use the original holes (I've sent them all out so I don't have one to measure).  An additional problem with the Indian product is how soft the shaft itself is - there is an amazing amount of flex from one end to the other and neither the centre bearing nor the end bearings are sufficiently tight to dampen it.

All-in-all, the camshaft is a precision part that has fallen way out of spec - and I don't think the Indians know where spec is.

I'm so frustrated with Indian QC right now that I'm looking at China instead of India for new engines, I know of a nifty Yanmar-type 10hp/1000rpm engine that can be slowed down.  It has a 23.5 flywheel and may be the way of the future.  Myself and a buddy are looking into what we can do to ensure good QC.