engine and drivetrain 74 Tii distributor question - which is best?

[Tiger75]

I have a 74 Tii stock engine. Have removed decel valve.

Stock distributor is the 013 - mec advance and vac retard.

To get the best performance ( for street not track) should I plug off the vac retard because isn't it just for emissions?

I have a spare dizzy that is a 002 that I rebuilt - of course no vac diaphram. Should I use it instead ?

Anybody got a distributor curve for the 013? - it is not in the Factory Repair manual.

[c.d.iesel]

the advance curves ARE contained in the BMW Repair Manual - you must be missing pages - it shows curves and diagrams for about 13 different distributors. For optimum performance - LEAVE it all connected and adjusted to the factory spec. for your year - using a timing light - really.

There is no horse power gain with what you suggest. There is MORE horse power LOSS with non-factory adjustments. Get those correct first.

This also goes for your fuel injection adjustments

[jgerry2002]

The curve is listed... by rpm. The biggest difference that I can see as that the advance at 1k rpm is higher on the 013. Otherwise from 1500 rpm onwards they are essentially the same (1 degree difference in range), though the 008 has 1 degree more total advance.

They are both timed the same... 25btdc at 2700rpm.

I am using a 008 mechanical... someone had a regular '02 distributor in my tii, rather than an 013. I pulled a near perfect 008 out of a parts car years ago so I figured I'll give it a shot.

[Andy74tii]

I was in your same situation. My mechanic disconnected the decel valve, then had to recurve (also rebuilt) my 013 dist to compensate for no vacuum retarding. He said it would have been about the same difference as using a good 008 or 002. The car has run much better ever since, but if I had an 002 available, I probably would have used it. Definitely a performance improvement without the decel valve, though, for sure.

[jgerry2002]

That decel valve is a nightmare when it goes crazy. When I first bought my car my idle would jump from 1k to 3k rpm. The damn valve was stuck. I removed it and went direct to the distirbutor, at least the idle stabilized. My car still had very marginal power, very flat down low and lazy up top with wrong distributor. Bent injection linkage did not help either.

[70roundtail02]

Sorry to thread Hyjack a bit here but have a question in relation to using Crane or Petronix, on the Tii. Does one have to keep with a distributor or can you go with one of those? I ask because I have a crane setup currently and might be dumping the tii engine into mine.

Thanks guys

Tristan