Measuring Piston Position

[V500]

Measurements to four decimal places are ludicrous on engines built 60 years ago by unskilled assemblers, and that have been "rebuilt" X number of times, had parts swapped around, and run on vastly different fuel to when it was built.
A stick down the plug 'ole, done properly, is more than adequate for these basic engines.
Not to say that accuracy isn't desirable, just that the "tolerances" are too wide for four decimal places to make much difference.

[limeyrob]

Is that a Kettle you've just bought?  I had one many years ago. Quite liked it but the handling was odd.  A65 was way better but the kettle engine and brakes were very good.  It was so smooth it actually needed a gear indicator.   It handled quite well 2 up but had a weave at speed one up.
Re-piston position - I'm using old ally knitting needles with notches filed on.  They are about 3/32 and go near as damn it vertical which avoids the whole angle plus piston dome correction since anything angled is moving across the dome.

[Rob Neal]

Snuck into the garage this morning, don't tell!  Picture of the ignition timing marks set at 34 degrees/7,7343mm BTD.  The other pictures show the valve timing marks.  Tried to highlight these to show up better.  Marks looks to be in the same positions as those shown in the Haynes manual diagram.  It would be easier if BSA had the marks align in a straight line and so remove any ambiguity with the set up.  Just my view!  Does anything look outrageously out of whack do you think?

[DAVE BRADY]

Hi,

BSA could have done better with these marks but yours do look right.  Although I have Boyer and Pazon fitted, I would say that your Vape looks right for the anti-clockwise seat up.

Dave.

[limeyrob]

The same diagram is in the BSA Workshop Manual page B33.  Looks like Haynes copied it and replaced the pencils in the original with arrows, still it confirms Haynes got the details right.

[Rob Neal]

Thanks everyone for taking the time to respond.  I'll now check the valve opening/closing position relative to the crank position in degrees btdc.  Will let you know when(if) I get it fired up correctly!

[limeyrob]

Can you revert to points to de-bug it and get it running then swap back to electronic?
This is a very common issue on old Land Rovers when owner swap out the mechanical dizzy for an electronic one and get all sorts of issues but never think to swap back and see what difference that makes.
When I had my A65 I fitted a Lucas RITA system, made a huge improvement, but the RITA was very tough and had a simple static set up that was within a few deg.

[Rob Neal]

The bike came with an old electronic ignition fitted so I don't have any of the original mechanical system to hand.  I fitted a brand new ignition and have also tried a second system which the supplier kindly lent me to try out.  I have nice sparks from both set ups so hopefully all is well here.  I'm now looking at valve timing.  Both cylinders give 140psi readings on the compression test which is good and I've confirmed earlier with club members that I have the valve timing marks set up correctly.  Covering the RH carb with my hand shows good vacuum being generated but the left one has hardly anything.  Valves must be seating correctly otherwise the left to right compression readings would, logically,  differ significantly.So valve timing?  I'm trying to check the point at which the valves open in terms of degrees of engine rotation as per the manual specs. I have a 68-103 cam fitted which is in good condition with new bearings installed and end float set by T&L engineering.  I'm measuring the beginning of the valve lift with a gauge resting on the top of the valve spring.  As soon as the gauge reads movement I check the timing disk.  Is this method correct as I cannot get anywhere near the figures (ATDC, BBTD etc) quoted for valve openings in the workshop manual.  The timing disk has been set using a dial gauge to find TDC so confident this is correct.  Any thoughts?

[limeyrob]

Do you have any theory as to how the valve timing could be wrong? If the camshaft and gear are the correct A65 parts there's not much left. I can only think one of the Woodruff keys is missing in the camshaft or crank gear, perhaps fell out as the gear went on and now its out of place.
I would do a basic visual check with a pencil in a plug hole to get TDC then rotate with a spanner on the crank and watching the valves and timing trigger.  You can easily see which cylinder is on what stroke.

Is it possible to cross 2 push-rods? Its so long since I built an A65 I cant remember. Unlike an A10 you can see the push rods are all seated and go to the correct rockers.

[Rob Neal]

I have checked the pushed rods and am sure they are correct, shorter ones at the back opening the inlet and the longer ones opening the exhaust. I even considered the rocker arms but these will only fit one way round and they are seated ok.   I will take a look at the woodruff keys.  I'm sure they were in place when I  fitted the gears but as you say, there's not much else that can be wrong! Thanks for your time on this. Rob