Temperature differential, left cylinder to right cylinder.

velo54 said:

But each cycle is triggered by a different trigger. They are fairly small in diameter and could easily be slightly different. 1 or 2 degrees? One trigger on the rotor fires the left cylinder on compression, the opposite trigger on the rotor fires the right cylinder on compression. Graham

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On the Boyer the box takes the 2 signals of the magnets passing the coils and averages them to produce a single break in the power to the coils. The averaging is to ensure the 2 signals are 180 degrees apart and the break in the power to the coils is every 180 cam degrees or 360 crank degrees and is applied to both coils as a wasted spark on one side and a firing spark on the other.

Is the compression the same on each pot? If you have more compression on one cylinder that higher compression cylinder will run hotter. Also, maybe invest in a color tune, which is a clear spark plug which let's you see how rich or lean your mixtures are in real time.

kommando said:

On the Boyer the box takes the 2 signals of the magnets passing the coils and averages them to produce a single break in the power to the coils. The averaging is to ensure the 2 signals are 180 degrees apart and the break in the power to the coils is every 180 cam degrees or 360 crank degrees and is applied to both coils as a wasted spark on one side and a firing spark on the other.

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That's great, but it is not how a Pazon works. Graham

General Data/Troubleshooting
This system can be adapted to work on many types of engine, provided
that the required firing interval is every 360° crankshaft / 180° camshaft.
This ignition is of the wasted spark type, i.e. both plugs spark at the
same time, every turn of the engine. One plug will fire on the
compression stroke and the other will fire on the exhaust stroke (the
wasted spark). Since both plugs spark at the same time, bad running/
running on one cylinder can only be due to a faulty plug, cap, ht lead,
ignition coil or mechanical problem, not the ignition module or ignition
trigger.

Steve's temperature difference is probably more likely to be a mixture difference rather than ignition timing. Swapping carbs over would prove or disprove that, i guess. Graham

kommando said:

The chamber is central and its oil still comes from the timing side, a chamber is just a very large diameter pipe and the timing side journal takes the first oil and then what's left get passed to the driveside. Its very complex modelling program used to make sure the engine parameters create equal oil film thickness at each journal and would probably also point out more flow of oil into the crank is needed. I saw a Subaru crank a few months ago, oil pressure had been compromised and the further away from the oil entry point into the crank you got the more wear on the bearings.

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What compromises the oil feed to the drive side is the leaky flanges where the crank cheeks bolt onto the flywheel. Every crank i have stripped has shown evidence of leakage here. Stop that leakage and the drive side has a much better life. The oil when it gets to the engine will pick up the heat from the pump, timing case and crank, so when it gets into the big end it is all at one temperature. The centrifugal force acting on the oil (in the crank) raises its pressure a lot, that and the hydrodynamic oil wedge created by the revolving big end is what stops metal to metal contact. The oil pressure in that oil wedge will be in the hundreds of PSI, measuring this pressure is almost impossible, it has to be calculated (a bit like gas turbines, more accurate to calculate the engine performance than test it on a dyno) This is another reason to reverse the big end shells to block the oil squirter hole, this hole bleeds off high pressure oil right from where it is needed most. Don't worry about oil squirting out, there is all the oil getting flung out of the big ends anyway.
Electronic ignitions using wasted spark don't have the facility to time each cylinder so you will always have a variation between each cylinder, maybe this contributes to the uneven heat detected.

concours said:

Just because they read equal at ambient, does not mean there is not an error at elevated temperature. Swap Sides and retest under load, report back.

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Nope. At least, not until i have exhausted other possibilities.

I agree your statement that they may diverge at higher temperatures and I had considered that. The difference starts to appear as low as 50C. When I ran it up the other day I got to around 160/140 and shut down, a few minutes later they had settled at about 110/110 and tracked together as they cooled further.

I am inclined to think that if it was the gauges they would cool different as well as heat different.

velo54 said:

Steve's temperature difference is probably more likely to be a mixture difference rather than ignition timing. Swapping carbs over would prove or disprove that, i guess. Graham

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I guess so. I've had a further thought on it. Mikuni fuel enrichment comes from a valve with a rubber seal, if that seal does not fully close a little fuel will keep the carb rich. The right side is cooler, I need to check the choke seal on the right, probably before swapping sides.

kommando said:

General Data/Troubleshooting
This system can be adapted to work on many types of engine, provided
that the required firing interval is every 360° crankshaft / 180° camshaft.
This ignition is of the wasted spark type, i.e. both plugs spark at the
same time, every turn of the engine. One plug will fire on the
compression stroke and the other will fire on the exhaust stroke (the
wasted spark). Since both plugs spark at the same time, bad running/
running on one cylinder can only be due to a faulty plug, cap, ht lead,
ignition coil or mechanical problem, not the ignition module or ignition
trigger.

https://www.pazon.com/media/com_eshop/attachments/PA2.pdf

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It can be the ignition rotor not centered accurately, A rotor slightly off center will cause uneven running/running on one cylinder. The very short taper on the rotor/cam can be easily miss-fitted. Get the rotor as true as possible. Maybe this is why Pazon altered their design of ignition rotor, to make it less sensitive to this problem.

velo54 said:

But each cycle is triggered by a different trigger. They are fairly small in diameter and could easily be slightly different. 1 or 2 degrees? One trigger on the rotor fires the left cylinder on compression, the opposite trigger on the rotor fires the right cylinder on compression. Graham

Click to expand...

Nope. The Pazon Surefire is exactly the same functionally as a Boyer. Their other ignitions are different and use hall effect sensors.

The Pazon SureFire rotor has two magnets set at 180 degrees to one another. The stator has two coils at 180 degrees to each other. They align twice per cam revolution (half engine speed, so once per engine revolution).

Both coils work together to produce a signal that triggers a single single spark every revolution. So the coil sparks on compression and exhaust strokes. I use a single 12v dual output coil but it works the same with two 6v coils wired in series, they spark together. Wasted spark.

It does not work as you say.

dobba99 said:

It can be the ignition rotor not centered accurately, A rotor slightly off center will cause uneven running/running on one cylinder. The very short taper on the rotor/cam can be easily miss-fitted. Get the rotor as true as possible. Maybe this is why Pazon altered their design of ignition rotor, to make it less sensitive to this problem.

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I think we are going down a hole.

kommando said:

On the Boyer the box takes the 2 signals of the magnets passing the coils and averages them to produce a single break in the power to the coils. The averaging is to ensure the 2 signals are 180 degrees apart and the break in the power to the coils is every 180 cam degrees or 360 crank degrees and is applied to both coils as a wasted spark on one side and a firing spark on the other.

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And the Surefire is exactly the same, as my 'similar' explanation. Both pickup coils work together to switch one spark per revolution.

SteveA said:

Nope. The Pazon SureFire rotor has two magnets set at 180 degrees to one another. The stator has two coils at 180 degrees to each other. They align twice per cam revolution (half engine speed, so once per engine revolution).

Both coils work together to produce a signal that triggers a single single spark every revolution. So the coil sparks on compression and exhaust strokes. I use a single dual output coil but it works the same with two coil wired in series, they spark together. Wasted spark.

It does not work as you say.

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Sorry Steve, you are correct. I was looking at the Altair and Smartfire, not the Surefire. Surefire is similar to the Boyer. Graham

velo54 said:

Sorry Steve, you are correct. I was looking at the Altair and Smartfire, not the Surefire. Surefire is similar to the Boyer. Graham

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Phew.....I was going back to check stuff!

Two different heat range plugs? One hot, one cold?

brg404 said:

Two different heat range plugs? One hot, one cold?

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Oh no. Two Denso IW27 plugs. And different pairs tried, both used and new. I was looking for a misfire until the coil went and was replaced!

SteveA said:

That is why I said put a spacer under the clip, half a notch. Also remember Mikunis have 5 slots on the needle, not the 3 that Amal uses..

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I’m always forgetting that people fit these foreign precision instruments.

I know it's a much more complicated installation, but I'd like to see EGT's on both cylinders and compare those to the plug temps. EGT's are a much better indication of mixture, and might help separate mechanical vs. mixture causes.

Would things like combustion chamber size, valve seats, or ring gaps also be contributors to one cylinder running hotter?

I'd imagine the combustion chamber volumes would be different on every head ever produced, or when cast from the original, one side is slightly larger than the other.

Or piston rings walking about in a running motor and maybe harmonic vibration got one cylinder to line up to create blow by through the gaps??

seanalex said:

Would things like combustion chamber size, valve seats, or ring gaps also be contributors to one cylinder running hotter?

I'd imagine the combustion chamber volumes would be different on every head ever produced, or when cast from the original, one side is slightly larger than the other.

Or piston rings walking about in a running motor and maybe harmonic vibration got one cylinder to line up to create blow by through the gaps??

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Question 1: well, yes.

My cylinder head is an Australian cast Fullauto, it has not been modified for larger valves and it's pretty much as it left Australia. Valves have been reground lightly a couple of times, and it'll probably get done again over the winter, unless I can think of a really good excuse not to take the head off!

I suspect that John Sneed US made Fullauto heads are as accurate as you can get, until somebody big valves it..

The pistons and barrels in use this year are different to last year, same differential readings. Gaps were measured, not adjusted and rings initially positioned with gaps separated. I would imagine blow by, when it occurs, doesn't depend on the nicety of gaps being aligned, pressure will escape where it can.