Anyone know how many teeth there are on the flywheel for a 308 or 328? Are they the same for all years? I'm not concerned with flywheel interchangability, just curious about the tooth count. Thanks, David
not sure but I'd say they are all the same as it's a gear to the starter and the starters are all the same. if it's in reference to your other thread about the digi's the ecu unit doesn't use teeth to count revs, just a crank sensor per bank for TDC
I know that you know this Scott, but you typed too quickly (something everyone, even myself, does occasionally) -- both Digiplex (308i-2V & 308QV) and Microplex (328) have an RPM sensor on the flywheel teeth. Otherwise, the sampling rate would be too low to interpolate when to fire the cylinders during engine acceleration and deceleration. David -- I think you might have to have someone make a physical count. IME, it's not something included in the usual F specs -- e.g., in the TR documentation, the only place it appears is in one of the WSM flywheel figures where a note "Z=146" got left behind in the figure with no other explanation given (and my physical count confirms my TR flywheel has 146 teeth). Or maybe it might be in the Mondial8 documentation when Digiplex was first introduced, but that doesn't guarentee they are all exactly the same -- I have a very vague recollection of the number 144 also being mentioned before (but don't recall the model).
yeah yeah a brain dead moment, I fixed it in the other thread. I'm fighting a screwy AC problem and another no injector driver issue on some other Ferrari's. I'm in the missing teeth mode these days on the stand alone systems and didn't think it thru anyway it's an interesting setup considering the calcs needed to set TDC for bank 1 with out a 'home' stop.
I was more concerned if the count was odd or even...Even it appears to be; now I count! Thanks all for the input! David
the M8 WSM shows a 2* increment for a flywheel tooth so I'd hazard a guess at 180 teeth, but Steve's right they don't give you much info on it.
The 328's tech specs indicate that the tach sensor is 10 deg offset. The image of the flywheel doesn't show all the teeth, but the CS 10 deg mark appears four teeth over. That would work out to 2.5 deg per tooth, or 144 teeth total. But thats a swag from what little docs are available. The SB on testing the sensor just lists an average voltage range at idle, not a scope trace. I didn't investigate closer, because the swag indicated that the rpm sensor resolution was nowhere near sufficient to produce the ignition map claimed for the Multiplex. Given the vintage technology, I'm guessing there's some kind of PLL circuit involved, as a car computer dating from the age of IBM XTs and Apple Lisas probably wasn't doing a lot of high order binary math between sparks.
