Timing M10

[ClassicRacer]

Can someone please direct me to a good article on engine timing for my M10. And any tips on how to improve engine performance from my 1979 USA 320i.
We just completed a valve job and it is running good, just not sure its running great.

Thanks in advance.

Mike

[uwbuurman]

If you have an US 320i it is a m10, not m20. M20 is a straight 6.

[ClassicRacer]

My bad, M10 4 cylinder.

[Jeroen]

ok so you mean info for adjusting ignition timing? Depends if you have the early 2.0 or the faceift 1.8 version.

M10B20 -8/79: 25°bTDC @1750 RPM. Contact angle: 59-65°
M10B18 9/79-on: 25°bTDC @2300 RPM

Remove and cap vacuum advance/retard hoses from the ignition dizzy. Inspection hole above flywheel near firewall.

[ClassicRacer]

Build date is 11/1978, How do I know if I have the Facelift or not?

[uwbuurman]

Pre facelift is 2.0, so b20. Post facelift is 1.8, so b18. Yours beeing from the same month and year as my 323i, is pre facelift. It has some facelift features, but unmistakenly has the pre facelift body and dashboard, if not changed by previous owners. So Chrome mirrors on the door, front valance with a long plastic strip, taillights without foglight to name a few.

[ClassicRacer]

So now that we know I have a pre facelift any tips or tricks to ensure I have set my timing correctly? We pulled the vacuum to the distributer and rev'ed it to 2200 RPMs and set timing with this method using a timing light.
Is there any special additive I should run in my fuel system? It seems to idle with a bit of what could be described as a miss.