E: Engine BTH Electronic Mag Timing Comet -Q?

[vibrac]

One thing to watch is the rock in the peg in the BTH and the play in the cogs. its a long way from the half time pinion to the mag drive the clearance of 4 tooth interfaces are involved always approach the timing mark from forward engine motion (never 'adjust' it by moving backwards) but conversely ensure the peg is in the center of any rock of the BTH hole
My figure 34 BTDC

 

[Jez Nemeth]

Talked to Pete at BTH about the electronic FMC1 for singles -quite clear that the starting point for the unit, and recommended BTDC was 36 deg, units are set for that.

I'm assuming that changes down from that will suit particular set up's better -

My consideration is finding an accurate way of measuring TDC initially, using a Gauge Dial helps some...Deg wheel has it's inaccuracies too, and as Vibrac mentioned the backlash from the BTH ignition cog being another point of potential inaccuracy.

David mentioned, and I agree -don't think there's any real way of getting it right, or totally accurate without putting on a rolling road and testing -strobe is only good to keep the accuracy once set.

 

[Bill Thomas]

I would have thought Jez , If you set up a strobe on your belt drive,
And marked TDC , Found by say the middle of 30 degrees before and after , Or any other amount,
Within reason,
Then you have a bit of slack on your 3 stud body fittings, To move back and forth ?,
Your looking for about 2 to 4 degrees at tickover ?.
Cheers Bill.

 

[timetraveller]

I second Bill's method for finding TDC. A solid stop down the plughole, at, say, 45 degrees and then use a degree plate to find the before and after TDC and then split the difference. Then go back and check it at least once more. I use an Allen screw down the body of a dismantled KLG plug.

 

[BigEd]

I second Bill's method for finding TDC. A solid stop down the plughole, at, say, 45 degrees and then use a degree plate to find the before and after TDC and then split the difference. Then go back and check it at least once more. I use an Allen screw down the body of a dismantled KLG plug.

Agreed. Using a dial gauge to find TDC is likely less accurate because of the very small movement of the piston on either side of TDC.
Whatever method you use there is always the possibility of inconsistency but taking up all the play going forward every time will give more consistent results.