Discussion in 'Norton Commando Motorcycles (Classic)' started by yves norton seeley, Jan 14, 2018.
I have done your trick to my 74 Interstate. Thanks ludwig.
Yves has answered this himself, both much earlier in this thread and in his recent answer. As he says, heat in the oven allowed the sleeves to move and a press put them back to where the should be. It is pretty clear that without such a lip there would be considerable risk of a sleeve moving with different expansion rates. Either the Maney alloy barrel or a cast iron one than has been sleeved has a lip on the sleeve and a counterbored recess to sit in, so the sleeve is clamped in place when the head is pulled down.
Ken Kanaga has detailed the Maney barrels on a couple of occasions on here as well.
To day I receive the Jim Schmidt .025" / .66mm cooper head gasket, but I don't know what to do: With the .60mm the result was fantastic and the gasket from Jim is .06mm
ticker, so I have to 2 options: or I take .06mm from the head or I left the head like it is at the moment??? your opinion please...
I alredy take the exhaust, carbs, oil lines and so on from the head, take all the bolts and nuts from the head off, give a tick on the rose to separate the head from the cylinder and call it a day.
Tomorrow I will take the head out the frame and I will do the Ludwig trick: make some plugs to put in the cylinder bolt recess, Ludwig you are a genius!
The most important thing I discover to day: I find the nut from the RH inlet valve adjuster on the floor off the head, just between the valves springs, I hope that I will not find any damage on the valve or pushrod...
Keep you posted
Leave it as it is Yves, you’ll not notice the effect of an extra 0.06mm on the gasket.
Why not try one of the .003" thick copper ring Head gaskets. Mine has been in about 5 years with no leaks (with pliobond and .005" copper wire).
Yes, I might look at that option again when I am trialling the alloy barrels. Numbers work OK. Will just have to be sure bolts/studs aren't bottoming. Though it is different hardware for Maney barrels anyway.
what I did yesterday and to day:
First I make the decision NOT to grind the head, like Fast Eddy the difference between the .6mm and the .66mm is only .06mm, so let's try.
Yesterday I make the plugs for the cylinder bolts recess and put the head on the engine, it is not that easy with the engine in the Seeley frame, but with the help from my friend John Dascombe we dit it, I torque the head and call it a day
This afternoon I retoque the head, put all the stuff around the head, exhaust, carbs, oil lines and so on, make the valve adjustement, the bike is ready to start tomorow morning, I will warm up the engine 10 minutes, let the engine cool down and retorque the head again and do the road test.
You remember that I found a counter nut from one of the inlet valve adjuster on the bottom of the head, I tchek the valves and pushrod's and don't find anything wrong, in fact the adjusting screw turn fully in the rocker and this keep the valve and pushrod save, thanks the Lord.
I hope everything will be fine tomorow
Keep you posted
If those plugs are .001" or .002" too tall its going to lift the copper gasket off the cylinder and then hot gasses can pass through and burn out the copper. Those alum plugs are OK for a composite head gasket that has some flexibility where the plugs can embed into the composite material. But they could easily cause a copper HG to fail. The fit would have to be exact and they should not protrude above the cylinder head AT ALL. When Ludwig mentions that his stand proud "a fraction of a mm" - that would be too much and would probably cause the copper to fail.
I think Yves earlier failure was due to a copper HG that was machined. That would require sophisticated equpt to create a uniform thickness and if it had a thin spot it would have burned through as it did. I have never seen a copper HG made from unmachined sheet metal burn through (has- anyone else?). I think it would have been fine if it was made out of plain sheet metal. And his .8 HG held up no problem.
Yves - I hope those plugs are exactly level with the cylinder surface - otherwise you might be looking at replacing that HG yet again.
the plugs are flush with the cylinder surface, to day I made a road test with your .66mm HG, so far so good, same to have the power from the .6mm back
I have to test different ignition timing in the next days and after go to the dyno to make the final adjustement on the carbs, if needed...
I have some works to do on the Norton and the two Triumph from Jagbruno in the coming days also, still very busy like you see
Keep you posted
Yes the Maney sleeves are about .002" above deck - its Maney's way of getting a little more clamping pressure around each cylinder. But it could mean less clamping around the pushod tunnels where most leaks occur. A small amount of difference may not cause a problem. But there is a point where too much difference would cause a leak. To get the alum plug even with the surface you would either have to fine tune the plug thickness - or cut shims to go between the plug and the bolt head. Shim stock is available in many thicknesses down to .001" or even .0005" (1/2 thou). Shim stock seems the easier way to get it perfect. The last tiny amount of difference is going to get filled and sealed with pliobond - without it any copper HG can leak.
The plugs look good and seem like a good idea - but I'm not sure if they are really necessary on a copper HG. I have never seen one blow out like Yves (except for the one Yves blew) and that one was machined and could've had a thin spot.
To day I did 100kms with the .66mm head gasket, the bike run very well, but I don't find the "itsy pitsy" power from the .6mm HG, should I try the JS .021" / .51mm with this gasket I will have a squish from between 0.9mm to 1.0mm??
I also try with more advance, around 29 degrees in place of the 27 degrees before, a bit better but I am not satisfied...
feel free to give me your valuable opinions please
Just for information, Paul Dunstall used to recommend full advances of 27 - 28 for 10.5 CR Nortons, 28 for 10.0 CR, 29 for 8.9 CR, and 31 for 7.4 CR.
Are these figures from his Tuning Manual? What he recommends there was not necessarily what he used.. Yves I think you should try and get to a dyno..
1mm is 0.0394” ie just under 40 thou.
In my experience, the squish should work quite well at 40 thou, but it is basically a case of ‘the tighter the better’.
With your Maney cases, billet crank, steel rods, and lighter pistons you could definitely go tighter than 40 thou.
I ran a Norton crank with alloy rods at 30 thou once and saw evidence the piston had ‘just’ been kissing the head. That motor was revving to 8k.
So, if you’re revving less than that, and have all of those fabulous internals, you should be very safe at 30 thou. Perhaps less if you’re brave enough!
But having said all of that Yves, I believe this level of tuning is really into the ‘fine tuning’ level and I really doubt the improvements would be noticeable by the ‘seat of your pants’.
Personally, it’s something I’d play with over winter, not during peak riding season.
All only IMHO of course.
I wish to try the .021" /.51mm, not to have more CR but to have more squish band effect, to me the squish band effect is more important as the CR
I keep my revs at 6.200 RPM
I order the .021 gasket from Jim Schmidt and it take me two days of work to do the job, I am used to do it now...
Yves, I think Nigel puts his finger on it.. I would set up the squish bands and then set ignition on a dyno. Am curious as to why you change up at 6,200 that is slightly below max power for a 750 with standard cam
Yves, I fully understand that your quest is to tighten the squish band a little more. And I agree with this as I am a squish band believer.
BUT... I really don’t think you will get a meaningful improvement.
I guess I am much more time-poor than you, so I’d do it next time I took the head off, rather than make it a priority right now.
But that’s just me Yves... don’t let me drag you down to my half heated level!
There are three main aspects to squish; quench, getting more air/fuel into play for useful combustion and creating turbulence.
With quench there is a diminishing return on suppressing detonation. I cannot cite the classic references but anything less than something on the order of 0.030 to 0.035 will not gain you anymore with regard to suppressing detonation so more (tighter squish) is not necessarily better as you will not gain anything here.
Getting more of the Air/Fuel mixture into play with a more central combustion chamber mass around spark plug is always a good thing provided there are no significant detriments to port/valve flow. If you know your squish area, you can calculate the volume based on clearance and compare it to the overall combustion chamber volume - maybe expressed as a percentage.
As for turbulence, one needs to weigh out how much squish area you have to work with. There is an ideal ratio of cylinder area to squish area. In this case, more might be better but again I read somewhere about excessive pumping losses due to too much squish area and too tight a squish clearance.
So, once you get adequate quench to suppress detonation, closing down the gap any further gets a bit muddy,.........so it depends.
I change at 6,200 becouse there is not mutch more to gain on my engine, I can ritch 7.000 RPM if needed, I just whait to have Rossi in front of me..
I am time poor to at the moment, 3 bikes from customer waything
I wish to understand were is the HP gone? the difference is not that mutch, just like a new knife and a knife that as cut ten T Bone steaks, but I can feel it.
I don't tink that I will do anything in the two comming weeks, but I wish to be ready for the drag race at September
Thanks four your support Nigel
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