512 BBi Ignition Timing Spec?

Your 224/81 OM shows the "10 degrees @ 1000 RPM and 29 @ 5000 RPM" is correct. What is your "source" for the other information (both are very large amounts -- 38 deg at 5K RPM would be an even more unacceptable amount at 6K RPM)?
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FWIW, I use the timing curve above on my '83 BBi (note the error in the english translation for static timing). My timing is digitally controlled (mech advance is locked out, springs removed, etc.). I have knock sensors as well, so I can see that the engine is content with those numbers.

Side note, you can go higher in total advance (32 deg at 6300 RPM) without getting knock on pump gas, but I haven't really seen any benefit.

You might have seen different numbers in the workshop manual – which has numbers for the 365 and 512 BB.

 

18 ° at 1000 rpm? that is very high and strange to me. I know no engine with such a high number at idle

 

Unless that "Service Training" manual has a separate ignition section for each model, I'd guess that they just copied the 365GT4BB information (and only gave the high limit values). The OMs show three clearly different ignition maps/specifications for the three models. I will say that they made it very confusing in some of the text they use in the OMs (by not being clear about when they are talking about what's happening at the dist vs what's happening at the engine), but, fortunately, each has a dist advance vs dist RPM graph. My reading/translation of the OMs:

365GT4BB OM
static engine timing at idle = 16-18 deg BTDC
distributor advance at 2500 dist RPM = 10 deg of dist rotation
distributor advance at 3300 dist RPM = 13 deg of dist rotation
engine timing at 5000 RPM = 36-38 deg BTDC

BB512 OM
static engine timing at idle = 5 deg BTDC
distributor advance at 2500 dist RPM = 15 deg of dist rotation
distributor advance at 3200 dist RPM = 16 deg of dist rotation
engine timing at 5000 RPM = 35 deg BTDC

BB512i OM
static engine timing at idle = 10 deg BTDC
distributor advance at 2500 dist RPM = 9.5 deg of dist rotation
distributor advance at 3150 dist RPM = 11 deg of dist rotation
engine timing at 5000 RPM = 29 deg BTDC

 

Yes (as will be the valve event timing marks).

 

you are sure you still have the original flywheel in your car?

 

You can "confirm" the location of the marks on the flywheel relative to the PM1-6 mark by knowing (or counting) the total number of teeth on the flywheel (call this "Z") and then calculating 360/Z to get degrees per tooth and then counting the teeth from PM1-6 to any other mark.

 

Nerd alert!......I just counted 147 teeth on a BBi flywheel (FPN #118367). Approximately 2.449º /tooth

Someone want to confirm?

 

In the WSM for cat-equipped TR, they kindly put a note "Z=146" on the flywheel diagram (page D64), but it doesn't appear on the non-cat TR flywheel diagram (page D6). Are you sure that you didn't miscount by 1?

 

Absolutely n o t sure. I did count twice, but I went from a picture, and two of the quadrants were well in focus, and the other two, not-so-much.
Also,, the part number for a 512BBi flywheel is different. (118367-BBi Vs 123923-TR). Probably would be the same gears (?)

Thanks for checking

 

I don't know either for sure that they would be the same (and for doing this estimate it doesn't matter much). The flywheels are almost always different part numbers (even for different versions of the same model) because the ignition and valve event markings are different.

 

BTW

I observed that the 10º at idle was not the best for my BBi in terms of tip-in throttle response, and starting. I actually backed off a couple of degrees and found this improved. I put it back to 10º a couple of times and my observations were consistent.

What I am curious about but have not checked this is the 29º @ 5,000 rev point. Car runs very well.

YMMV / IMHO / FWIW

 

I've experimented between 0 and 15 static, and I find a little less than 10 "feels" a little better as well. That's also impacted by base idle and A/F (eg, retarding timing to compensate for too much idle air is a false positive that the car "likes" lower static timing). So if everything else is correct, anything between 5 and 10 deg seems to work pretty well (IMO).

I run between 5-12 deg at 1,000 (ECU automatically advances/retards timing to control idle speed), 22 at 2,000, 29 at 5,000, and 32 deg at 6,300+. No knock on pump gas.

 

Can you elaborate on "idle air"? Do you mean lean greater than 14.7 AFR likes less advance? Or rather, if it's lean, it needs to have timing retarded?

I have ECU controlled mixture to produce stoich to make cats happy. It's a California thing. The motor runs better when back a little from 10º. Love to know if richer makes a difference? However, The engine does start much better when backed off from 10º. Also, it knocks on pump super, but then again, the CA fuel does not satisfy the BBi OM requirements (octane too low). Many variables.

Well it runs terrific, so can't complain, just curious. Thanks!

 

By "idle air", I mean the air that gets through via the idle bypass screw. Assuming this is letting in more air (and A/F is stoich), then idle RPM will be a little higher; which can be "corrected" by retarding timing a little. This will bring the idle back down, and give a little chop (makes the BBi cams sound less flat). Not sure this is really the "right" thing to do though. That said, I'm able to monitor and digitally tweak pretty much everything, and I still like the static timing shy of 10 deg when warm. I actually have the timing above 10 when cold (along with more air and more fuel). Not really sure that's possible in the stock configuration (AAV / cold start valve / WUR aren't changing timing).

FWIW, I set the idle A/F to 0.99 lambda (99% stoich). I have cruise lambda at 1 (stoich). By 5k WOT, I'm around 0.87 (~12.8 AFR). No knock on 92 octane. In general though, I do think these engines like to run fat up top (according to my butt-dyno).

Side note, I always used pure gas when I had CIS, but since the EFI/ITB conversion, I've been using regular pump (w/ethanol) without any issues.

 

Your comment "it knocks on pump super" is a bit surprising (29 deg BTDC at 5000 RPM is already very conservative so you wouldn't want even less). Are you sure that your WURs are adding enrichment at high load (i.e., they are dropping the control pressure when no vacuum is applied)? Also, your "ECU controlled mixture to produce stoich to make cats happy" should not be working at high load -- have you ever measured your O2 sensor voltage(s) at high load? The O2 voltage(s) should drop to 0.1~0.2V DC (rich) at high load. Do you have some sort of added throttle position switch to "tell" the ECU: "I'm on it so add enrichment, and don't try to run stoichiometric"?

 

I'm kind of mixing both posts together, but hopefully it tells the story clearly.

Thank you for the posts! It's great that you have those ultimate mixture controls throughout the rev range. With a lambda feedback (Bosch - Johnson Controls box) for emissions, you get any mixture you like, so long as it's 14.7 give or take a very small amount. It's this way at idle - all the way up the range just short of WOT. Then a switch will supply a fixed duty cycle to the freq valves when it is high enough up the rev range. The system is all operating correctly given pressure feedback measurements duty cycle measurements and exhaust sampling etc. What we don't have in CA is readily available higher octane pump fuel. The Ferrari Owners Manual for the Boxer calls out higher octane than the 308, {98-100 O.N. which is more like 93+ AKI}. There's the whole RON / MON / AKI values you grind through which confirms the Euro standard called out is higher than the max 91AKI available. (Thank you Wikipedia for the great detailed summary.) By the way, in the great state of WI, they have unleaded 93 AKI at regular gas stations for roughly half the price of CA 91 AKI. Anyway, I'm able to get some 100 AKI unleaded, and add the measured amount to raise the octane to 93AKI this cured the knock. If you have a higher octane fuel, and more mixture controls capability, then I can't reproduce this. After the cats, the car blows very stringently controlled HC/CO/NOx required for a 1984 emission-controlled vehicle.

This sounds a bit blasphemous I know, but please keep in mind that the F40 when tuned for CA had a HP jump from 478 to 525, all from dialing in more carefully the engine management. And the newer Ferrari's that satisfy CA are not short on power. 700+, .800+, 900+ are good numbers!

That 0.87 lambda or 12.8 AFR is great to know. This confirms some of the same results I saw when setting up the WOT switch. The awful part was the knocking at low rev's when accelerating, which the better octane takes care of. I do want to check more carefully the 29º deg BTDC at 5000 RPM. I suspect I could be leaving some ponies on-the-table. My neighbors are gonna love me!

 

If you're basically 14.7 until high RPM / WOT, then that might explain the knock. Essentially, you have to push through a lean condition before you get the fuel you need. Sounds like the best thing you can do to protect your engine is to make sure you're flooring it

By the way, I misremembered my A/F settings (I'm constantly tweaking). I just went and took a screenshot of my current fuel mixture aim table. I'm actually at 0.85 lambda at 5K/WOT (12.5 AF). If it's easier to grok the table, consider 35 kPa to be ~0% throttle, and 100 kPa to be ~100% throttle.

(0 kPa isn't really relevant since switching to ITBs – they just don't build as much vacuum as the stock plenum setup did).

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