Engine/Transmission (1994 - 1998) Pump timing question

[DPinkston]

When I look at a chart of timing data for a particular CPL or group of CPLs the left hand column lists degrees BTDC, the right column lists plunger lift. There are about 6 data points in each column. The data plate on the engine states the timing as well. Am I understanding this correctly that these charts are simply tools to let you know where you are BTDC by looking at your plunger lift?

Is the difference in timing between the various CPLs due to injector cam profile, injector pop off pressures, delivery valve size, emission requirements, or all the above? In the timing suggestions I have seen for enhanced performance I have not seen anyone recommend different timing points for a particular type of pump (160, 180, 215). Is this true or did I just miss something? Does anyone have a timing chart for a CPL 2174 they can email me?

Thanks,

Danny

 

[mikel]

Hello,



Ok, first off go here for the plunger lift chart, it covers CPL 2174.

Am I understanding this correctly that these charts are simply tools to let you know where you are BTDC by looking at your plunger lift?

I wouldn't use plunger lift to try and find TDC, search the forums for any of several good posts that tell how to find TDC by turing the exhaust valve rocker adjustment down and rolling the engine over by hand. The pump gear could have slipped and if it has and you use plunger lift to find TDC then you won't have true TDC.

Is the difference in timing between the various CPLs due to injector cam profile, injector pop off pressures, delivery valve size, emission requirements, or all the above?

If you mean 'Is the difference in base timing from the factory due to... ' then I'd say emissions more than anything. If you mean 'Is the difference in pump plunger lift that is needed to get the timing that I want due to ... ' then I'd have to say it's due to the profile of the cam in the injection pump.

In the timing suggestions I have seen for enhanced performance I have not seen anyone recommend different timing points for a particular type of pump (160, 180, 215). Is this true or did I just miss something?

You're not missing anything. Most people agree that 15-16 is safe with stock parts and makes for a nice running truck.



FWIW I run 15. 5 degrees on my truck.



I hope I understood what you were asking and did a decent job answering.



Mike

 

[DPinkston]

Hello,



Ok, first off go here for the plunger lift chart, it covers CPL 2174

Just what I needed, Thanks!

I wouldn't use plunger lift to try and find TDC, search the forums for any of several good posts that tell how to find TDC by turing the exhaust valve rocker adjustment down and rolling the engine over by hand. The pump gear could have slipped and if it has and you use plunger lift to find TDC then you won't have true TDC.

I wasn't trying to find TDC by going by the plunger lift. I was just wondering if I was interpreting the charts correctly. If for example I measure my lift at 4. 1mm and I know the crank is at TDC, then that means I am at 12. 0 degrees of advance. If it measures 4. 9mm then I am at 16. 0 degrees of advance.

I hope I understood what you were asking and did a decent job answering.



Mike

You did an excellent job of answering. I wasn't sure I could word the questions so that someone could understand what I was asking.

Danny

 

[mikel]

I wasn't trying to find TDC by going by the plunger lift. I was just wondering if I was interpreting the charts correctly. If for example I measure my lift at 4. 1mm and I know the crank is at TDC, then that means I am at 12. 0 degrees of advance. If it measures 4. 9mm then I am at 16. 0 degrees of advance.

Ok, I misunderstood that one sorry. Anyhow, what you just said about measuring plunger lift with the crank at TDC is exactly correct.



Mike