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Valve Timing 15 Feb 2021 22:16 #218917

  • cobbadog
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From my experiences with Hyster they should spelt with an "S" up front as that would describe the company perfectly.
When I can get back to it again I will look at using the U-Nead-It and get it close to being centred, then use the timing light to get it on target.
The springs for the mechanical advance are strong and I have no doubt they are returning to what ever the position it is when not running. I need a good grip on the shaft to advance it and it returns easily.
I have double checked that the shaft does run in the centre with no bends in it as all 4 lobes give the same point gap opening. Both manifolds or in this case they are all in one are surfaced ground and have a lovely new gasket between it and the head. When the engine is running and you spray some either along it the engine revs do not alter as if it was sucking air in and there are no exhaust leaks either.
Cheers Cobba & Cobbarette
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Valve Timing 19 Feb 2021 22:05 #219079

  • cobbadog
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Well I think I'm onto something here. With help from another pair of eyes and ideas it may be the rotor button.
I have established that this dizzy is a different model from what is in the book by looking at the only picture, but in searching for spare parts like cap n rotor button both model dizzies are listed as using the same parts which doesn't add up. The book shows a dizzy with a square section on one side. So if this is correct then the parts listed online cannot be right. Anyway I will be playing mainly with the rotor button first.
Cheers Cobba & Cobbarette
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Valve Timing 20 Feb 2021 08:54 #219085

  • jon_d
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The rotor button and cap are just a mechanical means to distribute the spark.

Providing the button is passing across the cap contact for the firing cylinder when the points are open; then all is fine. The gap between the button and HT lead contact pin needs to be spot on.

If it's not, it may affect spark voltage and final ignition timing/dwell. Because the spark voltage will need to be higher to jump across the gap. (higher voltage = delayed/retarded spark)

Your button has a curved (leading??) edge. It could be affecting the final spark timing.
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Valve Timing 20 Feb 2021 11:15 #219090

  • wee-allis
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Re the curve on the rotor button, it looks to me as if it is intended to be fitted to a distributor and cap with a smaller diameter. The arc of the button would normally be constant and parallel to the cap to avoid the differential in the gap.
As jon-d says, this varied gap alters both timing and spark intensity.
Suggest you hunt for the correct button to suit the dizzie you have.
Steve.
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Valve Timing 20 Feb 2021 13:02 #219092

  • Mrsmackpaul
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wee-allis wrote: Re the curve on the rotor button, it looks to me as if it is intended to be fitted to a distributor and cap with a smaller diameter. The arc of the button would normally be constant and parallel to the cap to avoid the differential in the gap.
As jon-d says, this varied gap alters both timing and spark intensity.
Suggest you hunt for the correct button to suit the dizzie you have.
Steve.


Im thinking the cap and button have been identified as the correct for the tractor, but the distributor is not the correct number

So the cap should match 5the rotor button I would think

I am mostly wrong

Paul
Your better to die trying than live on your knees begging
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Valve Timing 20 Feb 2021 20:44 #219099

  • asw120
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Paul, you underestimate yourself greatly.

Jarrod.

“I offer my opponents a bargain: if they will stop telling lies about us, I will stop telling the truth about them”

― Adlai E. Stevenson II
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Valve Timing 20 Feb 2021 22:08 #219105

  • cobbadog
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I re-visited the dizzy again today. We found the other day the rotor button is a poor fit onto the shaft. By this I mean that there is sideways movement on the shaft. Hold the shaft in the vice and with the back edge of the rotor button aligned with one of the lugs around the perimeter of the dizzy body that aligns with the terminals inside the cap then I could mo ve the rotor to the right by around 1/3 the width of these lugs which is possibly around 2mm.
Now thinking back there was what looked like a bit of cloth inside the rotor button and I thought it was a crude fix for a piece of felt that usually is found stuck in the end of the shaft as an oil holder and slowly let oil feed down the shaft to the bob weights. Now I am thinking this was a very crude way to remove this slack. I think the rotor button is not the correct one for this dizzy and have looked for a replacement.
I measured the gap in the top of the shaft that locates the rotor button then had to think outside the box to be able to measure the drive lug inside the rotor. SO good old blue tack came to the rescue. I rolled a piece up, stuck it inside the rotor and used a screw driver to push it against the drive lug. There is a difference of around that 2mm I mentioned earlier. So in the interests of being 'rough' I also replaced the piece of old cloth with some brand new cloth and made it into a "U" shape and sat it into the groove in the shaft and fitted the rotor button. It is now a firm fit. So while the dizzy was out I again stripped it down and went one step further than before and removed the bob weights to ensure they are clean and free to move and porperly lubed at the moment with light machine oil. When I spin the shaft the weights obviously move out as I do see them return back as it slows down. I also noticed that the weights do not return fully back to touching in the stop position. If I touch it they do but at the moment they wont and there is nothing stopping them returning. The springs are good and have tension on them but I have no idea why this is happening.

Then another helpful tip was put forward, bent or stuck valve even a bent push rod. So with out removing any push rods at the moment I rotated the engine and as each cylinder came up to TDC I was able to spin the push rods and there was no obvious sign of them being bent but I do relaise they need to be rolled on a flat surface to ensure this. The last time the engine was running it was bloody rough and some huge back fires with flames up the chimney, not good. So once again I checked the valves and looking especially at exhaust valves. All were to spec on the gaps but this does not mean that one or more are seating. Having said that, visually all valves both inlet and exhaust 'look' to be sitting at the same height. I am now thinking of removing the head and make sure that all valves are seated properly and that none are sticking. Sounds drastic but for a bit of time I can then discover if this is the source of my nightmares.

Another piece of info offered up is to look at the valve springs and their tension. They may look ok but not be up to scratch so lifting the ehad is looking more like the direction to go next. Exisiting springs are originals.
Cheers Cobba & Cobbarette
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Valve Timing 21 Feb 2021 07:26 #219111

  • Mrsmackpaul
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I believe you can find whether the valves are seating properly with just a simple compression test
If you borrowed Cobberette and the bathroom scales you should be able to use a small block of wood between them and the rocker and roughly check spring tension

I would think anywhere between 15 kg's and 50 kg's would be fine, we used to get spring pressure shimmed to 110 pound when we were young bucks building what we thought were fast cars
As long as the valve seals is all it needs to do, our high vavle spring pressure was to stop valve bounce at high RPM

Even bent push rods are usually only going to be a big issue at higher RPM's so I doubt this is of cause of the problems

Paul
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Valve Timing 21 Feb 2021 07:45 #219114

  • Swishy
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to check for a good valve seal
is assemble all the valves n springs etc az tho U ready to install head
tip the head upside down on the bench
fill each cylinder head with petrol n C wot leaks
cya
OF ALL THE THINGS EYE MISS ................. EYE MISS MY MIND THE MOST

There's more WORTH in KENWORTH
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Valve Timing 21 Feb 2021 11:49 #219120

  • cobbadog
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If you are interested there is a long speel on what has been done on the YouTube clip listed below.



Cobbarette would be very excited to help as she does like getting on the spanners but I can tell you now the only set of bathroom scales will not be allowed out to the tractor under no circumstances.

So yes with the head off and arse up on the bench using the Swishy method was one thing I intended to do but then since its on the bench pull the valves and see if any are sticking and double check the seats and faces.

Engine passes the compression test with flying colours at approx 78 psi right through or very close to.

So right now now backfires or flames up the chimney starts easily as usual but still has a flat spot and slight miss. Air mixture at this point and is the best so far is 3 turns out with very little sign of black smoke out the chimney at idle which it was doing.
Cheers Cobba & Cobbarette
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