Another cam degreeing question.

correct. Off the top of my head I don't even remember what the WSM calls for with my 12 I just use 1 and 12 because both stare me in the face.

 

Given you have manufacturing tolerances, probably not a big deal although #1 is the standard. I'd be willing to bet if you set the timing perfect on #1 then check all others you would find variances. Piston height, pin location, rod length, crank bearing journals, none of these features will be dead balls. Stack up on tolerances will cause a variance

 

Yes. One cylinder may be perfect and the others out (in theory). To make it 100% across the board you would need to adjust the rod length in each piston and we know that's not practical at all.

 

That is why it does not matter. Ferrari did not make sure 1 and 5 or 1 and 7 to be more accurate than the other holes. In fact cam timing is just a close approximation of and ideal running. Each engine cam timing may be different for optimum targets. At the end of the day that is why racer cam time put and put down laps to test. Then they change timing until lap time increases then they go the other way until a sweet spot is found.

 

Carl, if #1is the TDC for the whole engine why move the dial gauge to the other bank ?
Sark

 

Hi Sark,

Cam are set up individually on each bank with crank at #1 to TDC and all the cam shaft marks lined up. That is the end of the "set-up" phase. Then 1/6 is cam timed for precision and then 7/12 is cam timed for precision. That is the end of the "cam timing" phase. Cam timing optimizes running. I swear 90% of the cars out there are just "set-up" and run just fine. I bet there is not much much to be gained by cam timing. I have never run a ferrari back to back on a dyno to see what the effect is on HP and torque from set-up to cams timed. I have raced my 348 racecar cam timed then played with cam timing changes to see if I could get more power and the effort was just not worth it. I saw no statistical advantage given the problems with reproducibility on dyno's, air temp correction factors, race tire degradation, and my own ability to run consistent laptimes with deltas in 10ths of seconds to name a few issues. So if you are just setting up cams you will be just fine.

 

Separate belts, separate cam timing. Most Ferrari V8s are set up like two four cylinders on the same crank and the V12s like two six cylinders on the same crank. Separate ignition systems, separate cam timing systems, and separate exhaust systems on many models. On a Daytona and most earlier V12s, the 2 distributors for each bank were set up so each set of points ran 3 cylinders, even though there was only one chain driving the cams.

 

Hi Carl, I do agree 100%. When I was younger I was interested in expensive stereo systems because they were the only ones with higher price tag and better laboratory proven performances without knowing that human ear is not going to appreciate that.

Sark

 

Terry, bear with me for a moment. This is my understanding that TDC is a vertical mechanical movement measearment of a piston in a cylinder and has nothing to do with cams, valves and clearance between them. I assume when the # 1 cylinder is at TDC stroke in bank # 1 then the cylinder # 7 or # 12 in bank # 2 is at TDC stroke too. ( since they are driven by one crank shaft), Unless this statement is not true and actual TDC measearment at # 1 is different from # 12. ( mechanical wear and tear ). In that case doing cam tuning at TDC # 12 might be different from doing cam tuning when # 7 is at TDC on the same bank. Any body done any final cam tuning at one bank reference to another cylinder at TDC on the same bank to see if the final values are same.

Regards, Sark

 

Sark, your assumption that when #1 is at TDC, #12 is also, is incorrect.

When #1 is at TDC only #6 will be at TDC also.

#7 & #12 will be 60 degrees BTDC.

Study the firing order of our 12's and/or make a crankshaft motion diagram over the full 720 degree engine cycle, and you'll understand.

 

Thanks

 

Part of the issue is the factory reference marks are set based on TDC of #1. Those marks are useful for assembly purposes.

 

No. No reason to think #3 is any better or any more accurate than #1. The reality is though with modern machining technology things are very consistent. In the old days I remember seeing Ferrari V12's with a head off and you could easily see by eye the difference in protrusion of one piston to another. I had a good machinist friend once tell me he did not dare index (making sure all the crank throws were the same stroke and exactly 60 degrees from one another)a Ferrari V12 crank because some were so bad there was not enough material there to correct it. At a couple of points in their history between old worn out machinery, everything human operated and employee relations at the factory, workmanship could get pretty bad. We saw some really terrible machine work over the years. It has been quite good since the late 80s for the stuff done in house. About that time they stepped into the 20th century. Subcontracted parts are a very different story. Blocks, heads, cranks, cams and steel rods are done in house. Everything else is subcontracted.

When timing a motor out of the car I use which ever end cylinders are handier.

 

That was just what their level of ability was.

Read Speed with Style some time and see what Mark Donohue had to say about Ferrari.

They did not win due to technical superiority. They won races because there were there every weekend, usually with good drivers trying their hardest with whatever limited resources they had.