Timing...another opinion....

[BCFAST]

Had a nice visit with a long-time Cummins mechanic. He works only on B and C motors, but almost exclusively marine. 12 hours a day, every day, for 20 + years... . that's all he does... so it stands to reason, the guy knows his stuff. Anyway, he INSISTS that advancing the timing will murder the pistons in 6 months~! The marine engines can get away with it because of different pistons, but the road motors will burn up. I was telling him about my future plans for my Ram and he wished me luck... . of course, he didnt think I'll ever get even CLOSE to 400hp. LOL I told him briefly about some of you crazies, and his response was, "I'd love to see it!... they wont last very long".

 

[Cooker]

I have heard the same thing from different diesel mechanics at different shops here in town. At first I thought they were idiots, but now I'm starting to wonder if they were not so stupid after all.



I be very interested to hear more on this topic.



Thanks,

Ryan

 

[C Schomer]

At this altitude it's safe to advance about 4* on any engine. Craig

 

[DieselB59]

Okay, four years and 80K miles ago, I was told something similar by someone just as uneducated. Now, sitting at 16 degrees BTDC, I can see that they are all wrong! I have taken the head off to do a gasket replacement just to freshen things up, and the pistons and cylinder bores are all mint. In another 80K, I'll pull the head off again and smile once more, knowing that mouths and opinions have one thing in common... ... . EVERYBODY HAS ONE!

 

[illflem]

Chris, good to see you back posting again. I have a lot of respect for your input, keep it up!!!

 

[DieselB59]

thanks!

Thanks, Bill! I had been silent for a while. Though I was still checking in to see what was going on, I had lots of changes in my career and my personal life that I had to contend with first. It's incredible how fast the time flies now that I'm taking care of so many B series engines as a full time job. It's like having your cake and getting to eat it too. I am back in full swing now.

 

[HEMI®Dart]

Chris,



I was reading somewhere that said diesel fuel has an ignition delay of 13° (crank degrees) , depending on cetane content. So if a guys timing is @ 16° BTDC, fuel is injected at 16° BTDC, crank rotates another 13º before fuel ignites, so you really have about 3° BTDC combustion?

 

[DieselB59]

Well, resistance to ignition actually has to do with a few things. Atomization, Spray pattern, and Compression. All can and will be affected by different Cetane ratings.

 

[Smoker]

I think it depends on how far you go with timing before the pistons start to pit, melt , scar, whatever. When timing is set high enough to get what some would call "spark knock", it probably is doing damage. I know of two daily driven trucks that are set at 30*. It is true that they won't last as long with timing this high, but they will still go a long, long time. Keep in mind though that these trucks are built motors. I have my timing set at 26*. I have never had the head off of my truck and have never had any problems,... . yet. However, my truck is only used about once a weekend for dating and the rest of the time I use it for a pull truck. Since I intend to build the motor this winter, I thought I would test the factory pistons and see how much they can take. I'll take some pictures this winter and post them when I take the head off. Now for my disclaimer. I would not recommend doing this to a truck that has factory pistons if there is no intent of replacing them in the near future.