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[stinkwheel]

Update. My ebay parts look like the real deal, general fit and finish is probably better than the original one.


For reference, what deternines the travel of the auto-advance is how far the pin can move in this square cut-out on the back.


The Hitchcocks springs are way heavier than the standard ones, which is what I want.


With the unit fitted, the advance is pretty much bang-on 22 degrees.

Now confession time. It wasn't pinking. At least I don't think it was. I still couldn't get it to run right with a real knocking sound when under load going up hills. I decided to bite the bullet and drop the compression. Go so far through dismantling it and found this:


That's the inlet side.. So what I thought was pinking was actually it hitting the side of the pushrod tunnel, which for some reason it only does under load:


So that's the third bent pushrod in this engine so-far. I'm not sure I've been wasting my time chasing ignition timing though. I'm pretty sure kickbacks on startup are what's causing this. I had a spare pushrod the correct length kicking about. A very quick road test (lost the daylight and it's raining) showed no more pinking type noises. I'll need to set the tappet clearances again now it's settled and dial in the timing a last time because I'd been tweaking at it and hopefully normal service will be resumed!

[Wheaters]

I’d want to check that the valve spring associated with that pushrod wasn’t getting coil bound.

[Wheaters]

Having seen the photo of the back of the advance plate, I reckon a piece of copper tubing could be pushed onto the round pin, which would restrict the maximum advance a little,

[stinkwheel]

I’d want to check that the valve spring associated with that pushrod wasn’t getting coil bound.

Nowhere near. It's bent 2 exhaust and 1 inlet now. That one has done over 3,000 miles.





I'm beginning to wonder if I need stronger pushrods. Interestingly, the end caps are an interference fit over a 10mm rod. I've just spent the last hour trying to find a suitable steel or high tensile aluminium tube in an appropriate size. I was thinking 4130 steel or 7075T6 aluminium but it's like rocking horse poop. I can get 7075T6 in solid bar but it would be twice the weight of standard.

[Adrian]

For what it's worth, the Indian Bullet points assembly is a copy of the old mid-sixties Lucas C4 points assembly, the ATD is, I think, a copy of the Lucas item used on early side-points Triumph twins. If you can find some original NOS Lucas parts, try them?

A.

[Daiwiskers]

As Adrian said well worth trying
But make sure you get one where the can is Smooth the one's with the can that has a cut out is for right hand side mounting the smooth one is for left side this is the one you need
Hope this helps Dai

[Adrian]

Yes, you need to get one with the right rotation. An auto-advance intended for a 1965 BSA C15 will rotate anti-clockwise when you look at it face on, Triumph side-points twin is clockwise, same as the Indian Bullet. Good tip about the cams.

A.

[Daiwiskers]

The face of the wrong one has a notch cut out of it as you look at it end on

I think that makes more science than how I described it earlier Dai

[Wheaters]

Nowhere near. It's bent 2 exhaust and 1 inlet now. That one has done over 3,000 miles.

Well, It must have failed in overload so something else must be causing a restriction to the valves opening. I’m not up to speed with the history of your engine. Have you dismantled the top end yet to see what’s going on in there?

Alternatively, are the pushrods jumping out of engagement at the rocker shaft end and then getting jammed?

[stinkwheel]

I'm pretty sure it's kickbacks on startup that are causing it. Although the first one could have been a huge over-rev on a fluffed gearchange causing it to jump off the follower.

It's just had the top-end rebuilt after a piston failure and seizure, about 100 miles ago. That rod was straight when I did it and everything else loked tickety-boo. No violent incidents, over-revs etc since but quite a few backfires on startup.

I've ordered some 7075 alloy solid bar to make up a set of rods but they'll be (comparatively) heavy. Maybe not as heavy as steel tube ones would be though. I'll need to do some maths.