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Old 12-08-17, 10:11 AM   #1
JohnFP
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Default Problematic F Type

Hi all, I have an F type which I bought from an estate. Having spent two days trying to get it started I am seeking help. It has a Spark and I have checked timing by locating TDC through crank inspection hole. It hardly tries to go and appears to be blowing through the carb, the valve timing looks about right but I am wondering if the camshaft is in the wrong place. It has good compression.

Anyone know the valve timing so I can put a dial gauge on the pulley and check or are there easy to spot timing marks for the camshaft.

Thanks
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Old 12-08-17, 11:01 AM   #2
Lister M
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Where is the hole for the timing marks, I have an F and a mate has one and there is no hole, the timing marks are on the flywheel, any chance of photographs.
It doesnt have a camshaft as such, the valves are operated by an offset shaft off the end of the crank.
Martin P
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Old 12-08-17, 08:19 PM   #3
wolseley phill
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I suspect the OP is referring to the crank case inspection door.

If both valve rockers are moving as you rock the crank about TDC, then the cam timing is about right.

Is it possible to time the mag 180 degrees out on an F?

Phill.
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Old 13-08-17, 06:22 AM   #4
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Default Spark

I believe it works on a wasted spark system, so firing for every tdc.
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Old 13-08-17, 06:51 AM   #5
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The magneto only operates once every firing cycle.

Martin P
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Old 13-08-17, 07:03 AM   #6
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Is the mag chain driven or a direct drive with a flexible coupling?
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Old 13-08-17, 04:55 PM   #7
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Hi again, so I have attached a picture of the Camshaft drive gear taken at TDC, there is a small triangle on the cam gear which does not have anything to line up with so I am guessing that should be at the top when on TDC, does anyone know?

Any help with the position of my Camshaft will be appreciated, it does appear that the valves are opening and closing later than I would have expected, advancing the cam to align the mark at the top when at TDC will advance the opening closing sequence to a more expected pattern.


My enquiry seems to have triggered some debate about Mags and sparking, it can be seen from the picture that the top gear which is the Mag drive, the gear is same diameter as the crank gear, bottom one. This means the Mag runs at engine speed and will spark twice during one Otto cycle. There is a power spark and then another one after exhaust stroke and before inlet stroke which means the spark does not do anything and is referred to as "A wasted spark". This is also used an many car engines including the later Fiat 126 2 cylinder engine. There is no rotor arm or distributer cap as normally recognised, the coil has two HT connections and both plugs are fired at every TDC, meaning that always one spark is wasted, hence wasted spark system.


Excuse my ramblings which I cannot repeat in Latin, I did Metalwork, Woodwork, Technical Drawing and 3 sciences at school.
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File Type: jpg ListerCam.jpg (54.7 KB, 40 views)
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Old 13-08-17, 05:32 PM   #8
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Short history of the F type, there were two types, one that looks like a D type and one like yours, I own the D type style, they didn't make many like yours and then went back to the original design as it was more successful, it helps to identlfy which type thats why Rob asked. Top dead centre is timed, for both, from the Flywheel rim from stamped markings, if these have gone then when the flywheel shaft key way is pointing directly down then the piston is a TDC and the valves are stationary. Check the direction of rotation and turn the flywheel until TDC is 2" away from its position, this is where the points should open, rough guide.

Martin P

p.s. I dont understand Latin either
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Old 13-08-17, 05:39 PM   #9
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Ignore the timing marks and do it from first principles. Mesh the cam gear with the crank at tdc, and the valves 'on the rock' (I.e. exhaust closing, inlet opening).

Check carefully, if any of the marks now line up they might be the correct ones, I've known marks to be wrong from new.

Set the magneto at points opening, spark, at about 15 degrees before top dead on the stroke with the valves shut.

That's a basic start for virtually any four stroke, get it running and you can tweak from there.

Good luck!

Dan
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Old 14-08-17, 05:57 PM   #10
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Ok, got it going, problem was valve clearances were 3thou at bottom of cam but near lobe they were all over the place, put them to 10 thou and eventually after a lot of wanging it went.

Does not want to start once I switch it off, not sure why yet, suspect some carb problem but totally worn out after three days of winding it over.

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