simple how-to ignition timing

[trekkor]

Could someone point me to a thread or give me the steps I need to time my new 2.6 motor.

Built on a '74 7R case.

Webers, no vac advance.

What's the target degree at what rpm?

I'm really close to a great running motor.
Still snorting and popping a bit.

Thanks


KT

[Steve@Rennsport]

Optimal ignition timing depends on many things including:

1) Compression ratio

2) Camshaft profile

3) Fuel octane

4) Maximum outside air temps


Once you have that data, one can offer some constructive suggestions,...

[trekkor]

OK.

9.5:1
Solex cams
91 octane pump gas
max air temp 110, usually sub 90, high 80's.


KT

[911pcars]

An early S distributor and about 5º initial timing will get you in the ballpark. The total advance is about 30º BTDC.

However, to optimize the advance curve for any non-factory spec engine, I'd recommend some chassis dyno time where the operator tracks an optimal advance curve throughout the useable rpm range, then send the distributor to someone like Steve to replicate the mechanical curve with some margin of error for variations in operating condition.

Sherwood

[trekkor]

I should have full advance by 3500 rpms, right?


KT

[911pcars]

Originally Posted by trekkor

I should have full advance by 3500 rpms, right?


KT

The S advance curve is all in by around 2500 rpm.


Note: distributor speed = 1/2 engine speed

Sherwood