512BB valve lift

Good day Simon,

Attached is taken from the 365 and 512 BB/BBi service manual. I could not find any specific references to which car the data is for and so I assume it is correct for all models. If not, perhaps one of the experts can chime in.

Cheers,

Sam

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Never seen "40% PMS" nor "48% PMI" before for specifying a cam timing event -- any one know how to translate, or are those just typos ?

 

also never have seen this. valve timing is measured in degrees ( ° ) and not in %

sorry, never have measured

 

Thanks, those figures do a lot to explain things, and I now get why PMS = TDC and PMI = BDC in Italiano -- with "S" = superiore = upper (top) and "I" = inferiores = lower (bottom).

 

Valve timing is different for each model.

 

the main question has been not about the timing, it was about the valve lift and there in still no answer

 

Asked and answered. I knew they were very close to 9mm and thats what the only book on the subject says. The heads are nearly identical and the valves are identical. There would be no reason to change.

The 365 had 66 degrees of overlap. the 512BB had 70 degrees and the BBi 22 degrees.

 

the overlap says nothing about the valve lift

 

Good day Romano,

You are taking the "%" symbol too literally. The document was no doubt (hand) typed at a time (pre desktop computers) where the user's typewriter did not have a degree symbol and so they use the "%" symbol instead.

Cheers,

Sam

 

Good day Rifledriver,

I knew this for valve timing, but was unsure about the lift.... e.g. if it was the same across the models or not. Sadly, my comment was not as specific as it should have been. That said, thanks for clarifying!

Cheers,

Sam

 

I am unaware of any Ferrari engine other than competition versions or a great many special ordered that ever used more than 9 mm lift. That naturally decreased when 4 valve heads were adopted.

 

Brian: In addition to the Tipo 130 Colombo competition camshaft, The 275 Two-Cam Tipo 213 camshaft also is 10 mm lift at the valve (less lash).

 

Have you measured the intake duration and compared them to the intake duration values calculated from the BB512 OM and BBi512 OM cam timing specs? They are different:

BB512 intake duration = 260 deg
BBi512 intake duration = 244 deg
(Exhaust duration is 244 deg on both, and what Sam posted must be 365BB as it doesn't match either on intake nor exhaust.)

Wonder if you have BBi512 cams as that relatively lower intake lift (and less duration) is something that they did on the various K-Jet models (as K-Jet requires less overlap vs carburettors).

 

Thanks Dwight. I have a little experience with both.

 

That is what I'm thinking. I have only had one of these apart, an early 78, and the cams were the exact same spec as a 76-77 308 intake camshaft with about 9mm lift and 235 duration @ .050.

Adding to this: I have now seen Daytona's with 2 camshaft specs now. One with 252 duration @ .050 and the other 235 @ .050, both with about the same lift, 9mm.