8 BA Timing Indicator

[Phil Gillespie]

The indicator dimple on the pulley. Is this indicating TDC for No1 or is it 4 degree BTDC. AS when using a timing light you are seeking to line up at idle revs, so answer is?


Phil NZ

 

[V8 Bob]

The timing indicator on all late flatheads is 2 degrees BTDC.

 

[JSeery]

Yep, it is the timing mark, not TDC.

 

[Phil Gillespie]

The timing indicator on all late flatheads is 2 degrees BTDC.

Opps my mistake 2 deegrees BTDC on later flatheads.
So this dimple is at 2 degrees BTDC for No1. Not actual TDC for No1.
Phil NZ

 

[JSeery]

Yep again, it is the 2 deg BTDC mark and not TDC.

 

[Phil Gillespie]

Yep again, it is the 2 deg BTDC mark and not TDC.

Thanks must have been on the keyboard same time as you.
Thanks
Phil NZ

 

[Phil Gillespie]

8BA, Max 1 cam, single stromberg 97, fitted with GM distributor with vaccum advance.
Engine is in a 38 Barrel Nose with 11000 mls since rebuild.


Ol' Ron have read most of the posts including Richards descriptions also.
Seems this with the vaccum advance plus the mech advance is a good set up.
Just got one of those timing lights which allows you to check advance also.
Getting to grips with it and took some readings yesterday.


So disconnected vaccum advance and at idle rpm: 555 got the 2 degrees.
Reconnected vaccum advance and at same idle rpm got 12 degrees. Vaccum: 15 to 16 inch.


Took it up through the range with vaccum advance connected and got the following:


RPM Advance Vaccum & Mech.
652 16 deg
784 19 deg
960 28 deg
1260 28 deg
1580 32 deg
1980 37 deg
2480 37 deg
2520 37 deg.


So these results show a max advance at present of 37 deg. Vaccum advance of 10 degrees.
This appears to be too much in total. So to drop back on mech advance and also some on the vaccum to look at 25 to 28 maybe.
Present set up it goes well. This new timing light is a good tool as RPM also displayed.
Always appreciate comments and advice.
Phil NZ