Camshaft

[oiler]

Timing has a great effect on fuel efficiency, more than I expected.

With the original cam in the first 1000 hours fuel consumption was close to one litre/hour.
After repairing a loose cam gear consuption was as high as 1 1/4 litre/hour.  After retiming it was back to normal one litre and stayed there until the damn camshaft broke after 300 hours.

Now. To my big surprise with a new camskaft from Stationay Engine Parts it only consumes .85 litre an hour with the exact same constant loads of 2500 watts!

Am I wrong or..........is this possible?

[AdeV]

Am I wrong or..........is this possible?

It's possible, provided you're not exceeding the energy capacity of the fuel. Whilst timing is important, probably equally important is the cam profile, which will determine the valve overlap, max valve opening, dwell, and so forth, all of which will make a difference to fuel consumption.

[oiler]

That might explain why the new cam is better.

[cujet]

My twin has a significant camshaft timing issue with the injection pump lobe on #2. In fact, it's so bad that #2 cannot produce anywhere near full power. I can get the injection timing correct on both cylinders, but because of the lobe problem, #2 has very little total lift, obviously limiting the total output. If I adjust the pump for more stroke, the cylinder knocks like crazy.

So, I have concluded that the lobe is likely advanced by 30 or 40 degrees from where it should be.

I have a spare camshaft, so I'll take the time to "degree the camshaft" measuring the lobe timing on each lobe. I'll bet a dollar all of the cam lobes are positioned significantly away from the ideal. I'd expect nothing less from these engines. I'd also expect that a properly set up camshaft will result in significant economy and HP improvements.

Chris

[oiler]

My plan is to make myself a new shaft from a better material than the original.

Then position the lobes in accordance with my original Lister Startomatic. Hopefully this could improove both fuel efficiency and give me a longer lasting camshaft.

Any suggestions reg. materials?

Torsten

[cgwymp]

My plan is to make myself a new shaft from a better material than the original.

Then position the lobes in accordance with my original Lister Startomatic. Hopefully this could improove both fuel efficiency and give me a longer lasting camshaft.

Any suggestions reg. materials?

Torsten

What are the specs on a Genuine cam?

[JohnF]

I bought an OEM NOS twin camshaft from England and shipped it and an Indian cam down to a camshaft maker in Tennessee.  His comment on the Indian cam was that it was guaranteed to break because of the cam positioning and off-centre drilling and that any engine that had it installed would not get full power out of both cylinders.  He compared the English cam and determined that even that one was a few degrees out on #2 cylinder.  He has done all the measurements for me and is willing to build a cam to exact specs, in fact there are a few prototypes ready now.  I am shipping some engine pats down to him so he can install a cam into an Indian engine and prove his work.  After that I should have some cams available that will have the lobes exactly where the need to be.  As soon as they are ready I will let you all know.  Price is likely to be in the $300 range, a bit high but if they are as good as I hope, they will likely  allow long-term use of the twins, something I have been reluctant to predict in the past. 

[quinnf]

John,

It would be interesting to know whether the lift, duration, overlap, timing, etc of an Indian 6/1 camshaft is anywhere near that of one from a Brit 6/1, too. 

Quinn

[XYZER]

Guaranteed......no two camshafts are alike. I own 2 Injun oids. 1 is very smooth and quiet....the other suffers from sever intake noise and is imposable to get the correct valve timing. Many of us went and got intake silencers from McMaster Car to hide our problem. It will take a fine piece of tooling to locate the lobes using the tapered pin method. I have been tempted to take my quiet cam and have the noisy one ground the same.

[vdubnut62]

Many years ago, I raced a go-cart or two powered by the old flathead  Briggs & Stratton.
In setting up the engines, SURPRISE!! they don't grind their camshafts to anywhere near the same specs either!
Ron

[quinnf]

Sounds like maybe there's a market for aftermarket "hotrod" parts for these engines, John.

Quinn

[mike90045]

Sounds like maybe there's a market for aftermarket "hotrod" parts for these engines, John.

Quinn

Offset idler bolt
Bronze idler gear
polished lifters
real camshaft
roller bearing :fuel pump lever
Hollow dipper (non-fatigue version) & matching bearing shells
 
   What else is there???

[cujet]

If I remember correctly, The cam on the twin only needs one lobe removed for camshaft removal. Meaning, I could possibly TIG weld the other lobes in the proper position.

It's not unusual to see welded or brazed in place cam lobes on industrial engines. That way, the same lobe can be used for many positions. Even some modern cars and bikes do it to some extent.

Chris

[rcavictim]

Sounds like maybe there's a market for aftermarket "hotrod" parts for these engines, John.

Quinn

Offset idler bolt
Bronze idler gear
polished lifters
real camshaft
roller bearing :fuel pump lever
Hollow dipper (non-fatigue version) & matching bearing shells
 
   What else is there???

Chrome valve cover and dipstick! 

[Crofter]

I dont know whether you could get away with tigging all the other lobes without having too much distortion issues. I think the ones that are welded in manufacture by welding may use rigid jigging and post weld heat treatment. Depending on shaft material field welding may leave a very brittle zone at the weld borders. That would be a concern as a stress riser in an item that has high stress reversals in both lateral and torsional directions. It is a common failure point with welded on gears etc.

If you are down in the range of .20% or less carbon, brittleness would not be a factor but since the shaft is also run in bronze bearings it would be better for wear if it were higher. If you were making a camshaft with integral lobes then it would have to be of a material that would accept flame or induction hardening of the lobes so something up around 40 or 50 points of carbon.

The pinned on cams have the advantage of keeping the heat treating of the lobes separate from the shaft but the need to have them slip fit for assembly puts all the force transmitting solely on the pin and the drilled shaft hole, making for a bad stress riser to initiate fatigue failure.  I dont think there is a quick and cheap fix!