People still need to be taught this I guess

Are you talking about marks at the other extremity of the camshafts ? Because the ones on the pictures are not very close.

 

OK, thanks.

 

Brian- Cam four must have been finished on Friday afternoon, so no scribe/chisel mark. Those assembly marks are not too close on the front, but there are lots of Ferraris out there running poorly because someone used them for cam timing.

The scribe lines on the rear of the cams on my 575M were very close after degreeing the cams, but the circle was way too small for accurate timing. Plus you had to use a mirror to see them since they were scribed before the engine was installed. Great check, though, just to give you a warm and fuzzy.

 

Brian- Maybe not a Friday Ferrari, after all. Sorry, Tony.

 

Verify valve timing via degree wheel and dial indicator. Do it properly once, then routine maintenance of belt changes should be easy from there ever after. Power to be had by timing it properly aswell as extended header life.

 

I believe they are called witness marks

 

I find it amazing that the factory marks (assembly marks, witness marks, index marks, what ever you want to call them) are so random. It would take about 1/2 hour do design a jig such that the cams could be marked accurately. Given knowledge of the cam lobe geometry, the correct lash, and what the lift should be with said lash at TDC, there is only one angular position which will achieve that. After that, the changes in timing can only arise from wear of difference due to belt length tolerances, the latter amounting to about 1 degree variation max.

 

Do you think the inaccuracy of the marks be noticeable in the driving performance?

 

I'm aware of those things. Might have made sense in 1947. Since the introduction of CNC machining, inexcusable.

 

The answer is yes. This just happened.

A member on Fchat took his 456 to a well known but non-Ferrari specific shop for some exhaust work. While it was there, the shop found that the left bank cat converter was glowing red. They tried everything from FPR, plugs, wires, vacuum leaks, and checking the cam timing by inspecting that all marks lined up. The declared that timing was fine and they narrowed it down to a plugged cat converter or a bad ECU. Either was going to cost big.

My friend told me about their diagnosis and I told him to take it out of the shop because I knew what the cause was and I will get it fixed for him. The friend tried to take it out of the shop, and the shop said the car is disassembled on the rack and they would fix it if "your mechanic can tell us what is wrong with the car."

Since he is a good friend, I told them that the cause was one of the bank cam timing was off. They found it, fixed the issue with a proper redo of the cam timing using a degree wheel.

Sheesh, this is from a professional mechanic.

 

I own a concourse level 550 maranello that I got cheap because the previous owner a former Fchat'er. Having Past records are a joke because the past adds no value while highlighting malpractice. Two different big name Pro shops in my area replaced cats twice never understanding cats are a symptom not a cause. Finally a Cat fire scared the previous owner into saying uncle. He now drives Porsches and I own my second perfect 550. Proper Cam timing is a wonderful thing.

 

Mitchell is a real credit to the Ferrari community. I've been grateful he's lives near me and often cracks some hard cases. That said, I have no umbrage toward the shop I took it took either. They have always been courteous, honest, and forthright.

It reminds me of the story we 've all heard.
Refrigerator breaks, call in a mechanic - he hits the fridge, and it starts working again. He presents a bill for $100; the owner says - I could have done that. The mechanic says
Hammer: $10
Knowing where to hit them with a hammer: $90

I learned a lot of cam timing. Specifically, those marks are "assembly marks" for general guidance; the wheel is a must.

 

Brian, from the photos it looks like you use Redline Assembly lube during a service. Is this what you use?

Brian Brown
San Francisco Motorsports

 

Thanks for posting this. Great info since I am timing my motor soon.