How to set the points gap correctly

[Bergie]

I have played quite extensively with points gap over the week end on my Century 100 Villiers carb.



What is the correct method of setting the points gap? I turned the motor to TDC (by removing the spark plug and physically checking) and set the gap to 0,5mm. Then test tank is perfect with prop spinning.

I set the gap to its "widest opening" point, 0,5mm and test tank sputters.

The lock screw I move from the one end of the slot to other before setting the gap, but on the extreme side it refuses to adjust properly, i.e can't get the screwdriver and feeler gauge into the slot at the same time. Adjusting it on this end of the slot by trail and error, the engine runs very badly.

I basically set the lock screw in the middle or the other "adjustable" end of its slot, but in both instances on the same gap the engine respond differently. Am I being stupid or is the cam worn or something? I am sure that for a given gap, it should be irrelavant where the locking screw bites into the slot, yet this appears to effect this engine's running?

Please confirm which method I should use just so I can elimanate this problem.

[40TPI]

Always worth looking in the FAQ section first to solve the common problems...... http://www.saving-old-seagulls.co.uk/faq.htm but for further clarification .....................

Villiers........click on thumbnails to enlarge.



Wipac............ (essentially the same)



And in practice........



Slacken locking screw by turning anticlockwise............



Rotate adjuster screw CW/CCW to open or close points to specified gap whilst checking with feeler gauge............ Tighten lock screw clockwise when correct gap has been set. Recheck gap with feeler gauge. A simple two handed job!

Additional hint: Always worthwhile making sure the points have been scrupulously cleaned after gap setting!

Peter

[Bergie]

I'm doing as you said, I need to double check my procedure to ascertain I am doing it as I should. Right from the start I set the gap at fully open. Originally I think my problem was mostly loose backplate, but after setting the gap at 0,5mm at TDC seemed to smooth the seagull out rather than at fully open. (At TDC position, the gap is not at its widest opening.)

What would happen if the cam follower has been worn and how do I check for wear? I suspect a worn cam follower would open the gap wider and earlier?

[twostrokenut]

I suspect some of your problem may be the fibre heel on the points themselves , (I'm talking Villiers ignition here) , check them for wear.

Andy.

[40TPI]

The crankshaft cam (which is part of the flywheel) is steel on both Villiers and WIPAC magnetos. I am not aware of any published profile information however since the cam works against fibre composite/hard plastic I doubt you would be able to detect any wear in it. Any wear will be on the softer contact breaker arm following the cam. Wear on either the contact breaker arm or cam will reduce the maximum gap and delay timing however this can be taken up by periodic readjustment of the points gap for modest wear. The only practical way to check for wear is by comparison with known good components however unless the points arm is grossly worn such that you can't set the correct gap I'd be very surprised if you could not get a Seagull to run!

Peter

[twostrokenut]

I would totally agree with Peter , in that the points heel would have to be grossly worn to give any major problems.
That said , I have seen numerous Villiers points that are badly worn enough , a common cause of this being engines that have stood for considerable time , rust forms on the cam , and if folk have cleaned and adjusted points without removing the flywheel , this will not be noticed , and the initial running up of the engine , with the rust , and subsequent small pitting , can very quickly cut the fibre heel from the points , hence many people are continually re-adjusting points on engines that have been stood up for long periods.
This is probably more relevant to Seagulls (compared to other Villiers industrial applications) as many of them will have been used in salty conditions.

Andy.

[Bergie]

Thanks guys!

What you said made sense. This particular gull was plucked, boiled, scrubbed and put back together! Flywheel cam is smooth and shiny, points heel is making good contact with cam. Points itself also like new. Even had the flywheel remagnitized with the drill. It sure put some spark back in my life, but the gulls wings are not flapping so well although its flying, it does not like a boats, but the relationship with the bin is quite good!