The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Greybeard on 11.06. 2018 10:29

Title: My simple BTDC device
Post by: Greybeard on 11.06. 2018 10:29
I quickly made this up to set the mag timing. The rod is a tent peg and the top plate is a bit of scrap ally. I got the piston at TDC, made a mark on the rod then measured and made another mark at the correct place.
Title: Re: My simple BTDC device
Post by: KiwiGF on 11.06. 2018 12:10
I quickly made this up to set the mag timing. The rod is a tent peg and the top plate is a bit of scrap ally. I got the piston at TDC, made a mark on the rod then measured and made another mark at the correct place.

I use a similar method for my b31 and it is surprisingly accurate *smile* (the a10 is BTH electronic mag so timing was a once off degree wheel/strobe job)
Title: Re: My simple BTDC device
Post by: stanwhite on 13.06. 2018 17:32
I had a new, old stock spark plug...  For my 1972 Cortina that I sold back in 1986!

Thought it may be useful, so got busy with the milling machine and the lathe. And then discovered a "gotcha"

The plug hole has an internal lip at its outer side, so when I had made the "timing pin" to run as vertical as possible, it would not go in the hole. It does now, I tapered it...

My pin is just a couple of degrees off vertical, and that is insufficient to need to do trigonometry to get the "right" reading, so the pin is calibrated in 16ths, and at the top, 32nds...

The 4mm pin runs in a small brass tube, with a slot milled in the side of the spark plug to enable the tube to run at as much of an angle as possible. The tube is the "Araldited" into the spark plug body.

There is no chance that the pin could jam in the hole. Quite the opposite...  As the piston comes up, it "blows" the pin out of the hole! Nuisance, but a good safety feature, so I am not tempted to drill another hole through to relieve the air pressure.

I've gotta pull my mag off...  Oil is being a "Houdini" again, where the mag joins the rear of the timing cover.... Hence I made the "timing pin".

Greybeard, just saw your other post re not happy again... *problem* Real sorry to hear that...Be careful with those £175 "diamond encrusted" cam followers!

Cheers,

 Stan.
Title: Re: My simple BTDC device
Post by: Greybeard on 13.06. 2018 17:42
I had a new, old stock spark plug...  For my 1972 Cortina that I sold back in 1986.

Thought it may be useful, so got busy with the milling machine and the lathe. And then discovered a "gotcha"

The plug hole has an internal lip at its outer side, so when I had made the "timing pin", it would not go in the hole. It does now, I tapered it...

My pin is just a couple of degrees off vertical, and that is insufficient to need to do trigonometry to get the "right" reading, so the pin is calibrated in 16ths, and at the top, 32nds...

Cheers,

 Stan.

Lovely, looks like Punk art!

Reference the Ford Cortina spark plug: My brother-in-law tore the sidewall out of a brand new tyre on his Vauxhall Viva in about 1970. That tyre is still in his garden! I think he's hoping someone may invent a way of repairing it, but then he'll need to find a Vauxhall Viva to put it on!
Title: Re: My simple BTDC device
Post by: stanwhite on 13.06. 2018 18:10
Lovely car, I had one of those! I could use a timing light on it though...  As I still can on a Morris Minor, and my '78 Z1R.

Oldest thing I got is a radio. My Dad bought it when I was born, in 1949. I have done a small amount of work on it, still works very well..

I am still figuring if it is possible to use a timing light on my '61 A10 GF. I figure I could, but I might get a bit "oily"...! But in the meantime, my timing pin will suffice. At the moment, I figure it could be "over advanced". It has badly bitten my right ankle a couple of times, I actually thought it was busted the first time... My GF acquired a few "new names" at the time...   *razz*

Again, sorry to hear of your woes  *sad2*

Cheers,

 Stan.
Title: Re: My simple BTDC device
Post by: Greybeard on 13.06. 2018 18:31
I have the radio from my childhood. It's a Murphy. My parents bought it in the late 1940's.
Title: Re: My simple BTDC device
Post by: Triton Thrasher on 13.06. 2018 19:07
I usually use a pencil. Easy to put marks on with a knife.
Title: Re: My simple BTDC device
Post by: stanwhite on 13.06. 2018 19:14
I thought of a pencil...  Then thought I would probably be messing with the timing for so long, I could bust it. (Or worse, drop it down 'ole...! )

Probably the best is a drinking straw. A paper one, if anything goes wrong, the engine won't suffer...But I had an unloved plug, and some brass rod, a lathe, and a milling machine. And an "other half"  who is still not convinced of the justification for the machinery! ;)

Nice radio BTW Greybeard  *smiley4*

Cheers,

 Stan.
Title: Re: My simple BTDC device
Post by: Bsareg on 13.06. 2018 20:02
I too thought a pencil down the plug hole would be a good idea. Working on the goldie, pencil in, rock engine, snap. Pencil lying on top of piston in three pieces. Luckily I'd just bought one of those tiny cameras doctors use for "internal examinations". Working like a keyhole surgeon, with a steady hand my nephew fished them out the way they went in. I'll not be using a pencil again !!
Title: Re: My simple BTDC device
Post by: Triton Thrasher on 13.06. 2018 20:29
Well, there’s no doubt a pencil will break, if you break it!
Title: Re: My simple BTDC device
Post by: stanwhite on 13.06. 2018 22:27
Could always try a steel nail....  If that falls in, a magnet can come to the rescue....

My brass pin cannot fall in, it is placed in the hole of the "screw in" part, after that is screwed in. However.....  You can bet that "something unforeseen" will complicate matters sometime!  *problem*

 Cheers,

 Stan.
Title: Re: My simple BTDC device
Post by: duTch on 13.06. 2018 23:12

 I use a hi- tech small ss ruler with measurements that I line up with a mark on the oil feed pipe usually held vertical with a small zip-tie that seems to have jumbled ship but gave me a chance to utilise my new hi- tech banjo safety clip (NOT currently in timing mode)

Just took this pic for the purpose, and found one of my hi-tech street sweeper bristles that may also find its place in line
Title: Re: My simple BTDC device
Post by: RichardL on 13.06. 2018 23:40
Since this topic has reared its not-ugly head again, how can I resist showing my version (again). In my last go round with timing, I finally tried a timing disk, so my 1/32" graduations were not put to much use for BTDC, but great for TDC. I use a bent strip of thin sheet metal held to a head bolt with neodymium magnets as the indicator.

Richard L.

https://www.a7a10.net/forum/index.php?topic=368.msg99758#msg99758
Title: Re: My simple BTDC device
Post by: duTch on 14.06. 2018 01:47

 I'm a big fan of neom...ne neodymium (copied and pasted so if it's wrong is not my fault *smile*) where was I... oh yeah magnets,  good for a multitude of things like the bottom of a steel tin or tray to hold loose nuts and bolts and stuff- I just bought 100 12mm ones for various things...

 Now I'll pretend to stay on topic by *suggesting* that the stick really only need three marks ;
1 about 30 mm or so down to determine before and after tdc to roll back and forward and split the difference  for mark #
2 tdc, and #
3 chosen timing  mark

Title: Re: My simple BTDC device
Post by: RichardL on 14.06. 2018 04:26
Hmm? I wonder how my timing would be 1/32" more advanced? Darn! My timing mark is in the wrong place. Darn! My indicator moved, etc. To be honest, I don't get the bit about rocking back and forth between two arbitrary marks to find TDC.

 I suppose it's possible to use a three mark method, but I figured I could take advantage of my tools that aren't in the garage, that is, AutoCad drafting program. I know not everyone has this at hand, so I'd be happy to share the graticule image with anyone who wants to try it. (I've decided in advance not to be troubled if no one asks.)


Richard L.
Title: Re: My simple BTDC device
Post by: WozzA on 14.06. 2018 05:44
I must be the tight ar$e of the forum..  *red*
I use a plastic straw, a piece of brazing rod, & a hunk of tape..
Works for me..   *wink2*
Title: Re: My simple BTDC device
Post by: Brian on 14.06. 2018 06:02
This is BSA's suggested way to do it.