With regards to valve train maintenance, could someone tell me what the proper re torque figures are for 330 Heads and the general consenses as to what everyone is using for 330 intake/exhaust valve clearances. I see different numbers used from different reads, i.e.: Bishops book to owners manual.
Thank You
Cory
Maintenance specs
Re: Maintenance specs
Cory: I can't believe nobody else has responded to your questions, so I will take a crack at them:
1. Re-torquing the heads- The shop manual calls for 58-60 lbs/ft of torque. For a re-torque, I DO NOT loosen any nuts, I just pull each nut in sequence to the 58-60 loading. If any move, I do them all again until none move. Some cars (Alfa) call for loosening each nut, but I have never done that with a Ferrari. Others may have different opinions.
2. Valve Clearances- Historically, for 250 and 275 motors, bushed rockers used .006/.008" clearances, needle bearing rockers used .008/.010". 330 motors used .006/.008". However, for a still unexplained reason, the factory, starting about engine #8,300, for both 275 and 330, started building all engines with .008/.010" valve clearances. I have tried both settings and find very little difference. No discernible difference in noise, and a very small difference on the dyno.
Interestingly, 365 single cam motors specify .008/.010" in the manuals, but the Build Sheets show .006/.008" clearances.
I do not think you can go wrong with either setting. What you will notice is that the clearance varies as the roller is rotated. The rollers and bushings are almost never exactly round. So where the roller is positioned when you check the clearance will effect what you end up with. I used to always check each valve to find the "tightest" roller position, and then set the clearance at that point, so I would never have a clearance less than my setting. Eventually, I got lazy and do not worry about that anymore. It was all just too anal, and the engines do not seem to care about those small variances.
1. Re-torquing the heads- The shop manual calls for 58-60 lbs/ft of torque. For a re-torque, I DO NOT loosen any nuts, I just pull each nut in sequence to the 58-60 loading. If any move, I do them all again until none move. Some cars (Alfa) call for loosening each nut, but I have never done that with a Ferrari. Others may have different opinions.
2. Valve Clearances- Historically, for 250 and 275 motors, bushed rockers used .006/.008" clearances, needle bearing rockers used .008/.010". 330 motors used .006/.008". However, for a still unexplained reason, the factory, starting about engine #8,300, for both 275 and 330, started building all engines with .008/.010" valve clearances. I have tried both settings and find very little difference. No discernible difference in noise, and a very small difference on the dyno.
Interestingly, 365 single cam motors specify .008/.010" in the manuals, but the Build Sheets show .006/.008" clearances.
I do not think you can go wrong with either setting. What you will notice is that the clearance varies as the roller is rotated. The rollers and bushings are almost never exactly round. So where the roller is positioned when you check the clearance will effect what you end up with. I used to always check each valve to find the "tightest" roller position, and then set the clearance at that point, so I would never have a clearance less than my setting. Eventually, I got lazy and do not worry about that anymore. It was all just too anal, and the engines do not seem to care about those small variances.
Re: Maintenance specs
Dyke
As always, thank you for sharing your invaluable knowledge. Have a good holiday season
Regards
Cory
As always, thank you for sharing your invaluable knowledge. Have a good holiday season
Regards
Cory
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- Posts: 1906
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- Location: San Francisco Area
Re: Maintenance specs
Dyke, do the roller bearing followers tend to spin more true than the bronze ones?
What is the rationale for wider clearance for the the roller type?
Thanks.
john
What is the rationale for wider clearance for the the roller type?
Thanks.
john
PF Coupe
Re: Maintenance specs
John: I do not know the answer to your questions. It is possible that the wider clearances had more to do with the Tipo 130 cam profile that was used in most of the "roller" race engines. Maybe, they just wanted some additional safety measures during long races to keep the valve clearances from closing up too much.
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- Posts: 1906
- Joined: Wed Sep 04, 2002 12:13 am
- Location: San Francisco Area
Re: Maintenance specs
Thanks Dyke. With the bronze insert bushings it's not uncommon to have .001" difference in the clearance as you turn the roller. Does this happen with the roller type as well?
john
john
PF Coupe
Re: Maintenance specs
John: Yes, both types can give varying clearances around the roller.