engine and drivetrain Yanking CD's (timing) chain!

[wegweiser]

Alright CD.....(and we'll discuss this more over beers in Connecticut some time!)

I’ll take issue with the use of timing lights as the be-all, end-all gospel of tuning. Sure – they’ll get you in the BALL PARK…but that’s it.

1 or 2 degrees MATTERS.

Consider how many different ignition distributors were used on the 02 series (3?…4?…anyone know where I can get a “real” 009 tii distributor and not the replacement 002 unit????)

Consider also how many different compression ratios were used from year to year, US vs. Euro

Consider how many people out there have OTHER than perfect compression per their owners’ manual (it’s probably either LOWER due to wear, or HIGHER due to engine mods, head resurfacing, or just plain carbon build-up!)

Now…imagine you’re standing there with your static timing light trying to focus on the little steel ball on the flywheel, with the engine at 800-er something rpm, and all your vacuum lines disconnected or plugged per the factory repair manual. Consider all the above variables – and then ponder the thought that BMW offered only TWO….count ‘em TWO flywheels for the manual cars – one pre 74 and all tii, the other 74 onward.

Doesn’t seem so “ precise ” given all the other stuff they changed, does it?

I’ve always been taught to shoot for setting the maximum permissible ignition advance, say at 3800 rpm. This generally yields the best performance, if at the sacrifice of no longer masking a wonky, worn out, flogged distributor weight/spring/shaft apparatus. To do this – you actually need an adjustable / dial type timing light. I use the front crank pulley, marked at TDC #1 and go from there…..and by “go from there” I mean…..use my EARS and ASS and experience, to dial it in.

I ain’t blow’d one up in 20+ years this way.

Your mileage may vary. The factory settings are good for the inexperienced, or for those worried about piston meltdown…but they RARELY yield the best performance (HP) gains.

paul

[KFunk]

I'm with you Wegweiser. However, I prefer just rotating the distributor till I get what I want. Timing light on the flywheel just gets you a weak engine that'll run OK. Advance it all you can and take it for a drive.

My compression is really bad, though.

By the way, thank you for throwing in a completely random picture at the end of your post just to confuse us. -2 points for being a car, and not a motorcyle w/sidecar.

[JohnC]

I tend to want to do things "by the book", but I just recently timed my tii using the "Italian" method (so I've heard it called - No slur intended 'cause I is one!). I started by timing to the ball at a lower RPM, which was too advanced - pinging. I backed off little by little until I could accelerate uphill with no pinging. Runs great!

[peteinjp]

I tend to want to do things "by the book", but I just recently timed my tii using the "Italian" method (so I've heard it called - No slur intended 'cause I is one!). I started by timing to the ball at a lower RPM, which was too advanced - pinging. I backed off little by little until I could accelerate uphill with no pinging. Runs great!

I was taught this way when I worked at an independent bmw shop. Static time then find a hill in 3rd gear. The biggest variable had not been mentioned yet and that is fuel quality. The specs for euro and US cars differ in relation to fuel quality or so it seems in the factory manual. Here in Japan I dialed my tii in with factory settings on a new distributor curved within spec (9.5:1 stock bottom end fresh e12 head, rebuilt/ replaced entire injection system.) It pinged at high engine speeds WOT on slight inclines. Had to pull it back a couple of degrees. The gas here just isn't as good as 94 octane in the states.

[CamB]

With our fuel, I have a narrow window - too much advance and it pings, too little and it won't rev to where I need it to (6000-6500)rpm. Mine was set with an adjustable light off TDC on the front pulley.

[wegweiser]

The "completely random" picture is of a vintage Ginetta G16 - possibly among the sexiest racecars ever put on pavement....and it has an M10 powerplant. I've seen this very car beat the SNOT out of big American V8s at the track...over...and over...again.

English company

German motor

good driver!

Paul

[wegweiser]

...using a timing light allows you to DOCUMENT things - I have a binder with timing and carb settings, noting weather conditions, etc. It's as close as I can get to actually dyno-ing the thing (no time, saving money for move).

The exception to my philosophy on timing might be tiis...where having the pump and distributor correctly timed to each other (ie: sending off the parts to a tii guru in California or Chicago) is worthwhile, make sure the injectors are checked and tested, too. Expensive, time consuming, etc...but if I had an early 10:1 tii motor - I'd save the pennies and do it that way for sure.

I've ridden in only a few (2?) tiis that really lived up to the hype of the 70s motoring press (real Euro spec piston early ones) ...and they were set up THAT way.

Paul

[Mike Self]

getting in the ballpark with timing light and dwell meter. Unfortunately the ballpark meant my new rebuild (284 Schrick, 9.5 pistons) was pinging constantly--on premium. Loosened dizzy clamp, backed of a smidge and... no ping.

After reading on the board that one could run midgrade or even 87 octane regular with 9.5 pistons, I filled with midgrade; with a little more backing off I get just a hint of ping on large throttle, low rpm acceleration.

My late, much-missed father-in-law would be proud of me. That's how he taught me to do timing...

mike

[jimk]

I see the point of all the performance timing discussions and I do the same (only I bring out the laptop and modify my timing map).

But I defend CD's factory prescription because for the average beginner who it is that most of the "how do I time it" questions come from, his method will produce a fine running car that doesn't talk back if fuel is bought from station B instead of station A.

Super performance tuning is fine if you don't mind lifting the hood whenever conditions change slightly. (People will begin to think these are junk if you have to tweak them all the time!)

[Mike Self]

and got excessive pinging. Thus I had to back off (retard) my advance to get rid of the pinging--and incidentally made the car idle more smoothly and start better hot (at least I think they may be results!)

And at least for me it was easier to do it by ear. What I probably need to do is have a dizzy expert recurve my distributor for more precise advance to take advantage of the higher compression and hotter cam and still avoid pinging. Unfortunately dizzy places are getting harder to find...

mike

[TobyB]

turn into after 20 or 30 years

most people discover that the 'right'

setting doesn't work for them, either.

Better, I think, to say- 'start here and see what happens'

than to proclaim from the mountaintop that

"THIS IS THE WAY"

and confuse the pants off the occasional wrench

who's stuck with a dog of a car when it's

'on the ball'

I've found flywheels with no ball, 2 large holes for the

sleeve (so that the ball's wrong) cranks with no sleeve (!!!)

and all the other permutations that will make the ball method wrong.

I put timing marks on the front pulley, made a good pointer,

and am happier. BTW, I run 37(ish) degrees total, (over 4500) and the rest

of it's down to the crapo springs that reside in the distributor.

Incidentally, you don't make max power with max advance. Depending on

the engine, you usually make max power well before it starts to ping...

ideally, you want to run the minimum advance that gives you the maximum

power output- which, of course, means the dyno.

Nothing wrong with the butt- dyno, btw...

blah.

Toby

[Guest Anonymous]

Hey, I'm blinded by the flashing light. Which direction do you point this thing anyway?

P.S., I find some of the sounds emitted by my Bosch equipment quite melodic.

[wegweiser]

mid grade fuel in your fresh 9.5:1 engine MIKE in Beavercreek????

Indeed - you save an entire $2.40 on every tank full!

Those 9.5s deserve better than 87 or 89 Octane, don't you think! :-))

*slaps forehead*

Paul

[Mike Self]

premium setting and I have no ping on midgrade. And the idle is smoother and it starts better. Seems to me like I made an improvement ;-)

mike

[tjones02]

That is, SMOKE cars w/ more than twice its horspower using an M10. Including the McLaren M8A Can-AM and Porsche 935 in pic 3! :-) Waaayy cool!