Custom ground high performance camshaft

[buickanddeere]

  Now that everybody has agreed on port modifications in the Lister forum...................
  I would assume British built Lister and Petter cams would be built true and only suffer normal operating wear.
  Cam lift, cam duration and lobe centers on an Indian built twin would be suspect in particular.
  So what would there be to gain or loose to grind a cam for peak torque on a Petter for 1400rpm on a direct coupled 50Hz machine. Or 1700rpm on a Petter with a 60Hz generator?
  The Lister of course would pretty much aim for peak torque at 650, 800 or what ever the desired rpm is?

[mobile_bob]

here is my take on the subject

we have already determined empirically that the listeriod is getting enough air

and we know from experience that the compression ratio is high enough as is, so...

what would we hope to gain with a different cam grind?

typically a different cam grind would be used to alter dynamic compression ratios, and in order to arrive at a grind that would increase air to the cylinder we would also need appropriate lengths of intake and exhaust runners to take advantage of any changes in the cam grind...  both of which are many feet in length for engine's running in and around 650rpm

i don't recall but memory serves me we need an intake runner some 20ft long in order to get the standing wave boost,and a 20 ft long runner would have higher frictional losses that what might be gained in standing wave boost in intake pressures... therefore the reason why we don't see much work done in trick cam grinds, porting and all that jazz for engine's in this bore/stroke running at these low speeds.

everything i have read, and it has been quite a bit, tells me that we are not going to gain anything with high performance grinds on the cam lobs for these engine's.

maybe i am missing the goal here?

remind me of what the mission is?  more power? higher efficiency? cleaner exhaust?
some/part/all ?

bob g

[mike90045]

Isn't the idea to really get a PROPERLY ground and timed, zone hardened camshaft, that is not prone to break at known weak spots ?  Not a "racing cam", but a good, proper cam?

[deeiche]

I do remember a poster on the associated mirocogen forum creating a custom cam for his Witte.  I believe he reported running his Witte at 300-400 RPM.  So I could see a custom ground cam for a Lister if you wanted to run it a lot slower.

[buickanddeere]

Isn't the idea to really get a PROPERLY ground and timed, zone hardened camshaft, that is not prone to break at known weak spots ?  Not a "racing cam", but a good, proper cam?

I was thinking more along those lines. Long duration and overlap will make starting difficult due to low cylinder pressure.
If the opening of the exhaust valve was delayed to almost BDC. Would here not be a wee bit longer time with thrust on the piston? As long as the valve is open 50thou by BDC there will be very little cylinder pressure.as we are no trying to wring the last HP from the engine. A slight reduction in exhaust duration should matter little?
   A little more acceleration on the exhaust lobe and higher lift could possibly make up the difference for late opening?
  I had the Peter cam specs and John Deere two cylinder diesel specs around here somewhere. Wonder if there is any appreciable difference as they are both slow speed diesels.

[buickanddeere]

Jd two cylinder diesel valve timing. Peak HP at 1125 rpm . Torque rapidly falls off after 900rpm

Intake opens 12 BTDC
Intake closes 28 ABDC
Exhaust opens 48 BBDC
Exhaust closes 12 ATDC

Petter PH .Surprisingly flat torque curve  and rated up to 2000rpm. Peak torque at approx 1700rpm.
Could be that the Petter has better breathing ports and valves than the JD ?
PH peter is feeding 40cu" per cylinder. JD has either 188cu" or 235.5 cu" per cylinder.

Intake opens 4-1/2 BTDC
Intake closes 35-1/2 ABDC
Exhaust opens 35-1/2 BBDC
Exhaust closes 4-1/2 ATDC


What is it with the cranky British engineers that went with the 1/2 degree on the cam timing ?

[xyzer]

After owning 2 Listeroids one a Vidhata and one Powersolutions I learned that the "noisy intake disease" prompting us to install a Solberg intake silencer was due to the poorly timed assembled cam. I never figured out if is the incorrect rotation of the crank timing gear or miss location of the pinned cam lobes but there were a lot of us with this disease. There seems to be no performance issues between the 2 but I sure would like to quiet down the noisy one. A try with a replacement cam might determine if it is the cam or the crank timing gear. I always wanted to just give it a regrind as an assembly to bring it to spec. If it is still noisy then retime the crank gear. Assembling a cam the way they did it on the listeroids is a bit of a crapshoot. If it was ground as an assembly it would eliminate problems.......just a thought.
Dave

[Horsepoor]

There is an excellent thread on the sister forum at: http://www.microcogen.info/index.php?topic=913.0

The comments about a machine shop in Tenn working on a custom ground camshaft for about $300 got my attention, but, as far as I know this has not come to pass yet. Can anyone provide an update or a source?

Bruce

[38ac]

I am with XYZer in that I think we have decent enough quality lobes for the CS but pretty sloppy assembly practices is more the problem. I would add that as far as I can tell sloppy assembly and timing is NOT an India exclusive. The noisiest intake I have ever personally owned by far was on a real CS Lister 6/1.
I have assembled a couple cams for my personal engines with Indian lobes and gears but using good hard shafting.  Correctly timed them and also corrected the lobe positions so the damn intake lifters spin like they should. It is a 8 hour job doing it on a one at a time basis.
I could build a jig and stand so I  could crank out  properly timed camshafts ( on my engine block and my crank shaft but what about yours???) that is easily accomplished.  Checking and correcting (if needed) or even custom cam lobes is not a problem either.
The real  problem with correcting the cams is three fold,
 A. Properly timed and positioned lobes on my block and using my crank doesnt mean they will be proper on yours.
 B. The number of total people who are messing around with these engines is really pretty small to begin with
 C  The number who would be willing to cough up the required $$$ to correct a camshaft   "problem?? what problem??  is unfortunately  even smaller yet.. I think?

[buickanddeere]

Sorry,I must be missing something as I have yet to pull the cam from my Petteroid. Only have the cylinder and head apart. Going to finish them first.
Is it the Lister the Petter or both that pin the lobes to the camshaft?
What would motivate the Indians to use such a round about method of cam manufacture?
 

[38ac]

No, you are OK, I kinda pulled it off topic with the lobe deal. Very likely improvements are to be had with todays profiles over 1930s best designs. If the average Indian cam is as far off as the Indian cams I have personally checked out have been I think that a person would see a large change from just getting the original lobes right and maybe as large a change from experimenting as you suggest? That's a whole lot more playing around than I have time to do but would read with interest should somebody wish to take it on??

I own a two G&G Gears Mfg Petteroids and both have one piece cams unlike the CS clones. The reason ( I suspect) that the Indian CS clones have pinned lobes is that is the way the originals were made.