Where does the diesel noise come from? I was thinking lifters, but when coasting there is no noise. I started adding 2 cycle oil and no reduction noted. Could it be the injectors? Pretty noisy clicking when going uphill at low speeds especially in the morning before operating temps reached. 161,800 and don't know if the valves have ever been adjusted? Only owned it for 20k miles.

I knew AH64ID had some info on this and I dug up this thread. Says it is smoother at low boost because of more air, and that was with just a stage 1 colt. I am not sure if the power is smoother or if the noise is smoother though, maybe he will see this and confirm. At idle I would expect the engine to be going so slow that there wouldn't really be any air flow issues and the engine already runs very lean. Your experiences seem to say otherwise and I'd like to dig up some more info. Do you have the lift specs on it?

I got to do some digging on my lift pump today. Sorry I was vague in the other post. It is a Carter P4601HP. From what I have found it flows "100 GPH at 14psi free flow". It was a BD Diesel kit. I still have the factory filter housing and the pressure is being read at the injection pump inlet. Thank you in advance.

I got to do some digging on my lift pump today. Sorry I was vague in the other post. It is a Carter P4601HP. From what I have found it flows "100 GPH at 14psi free flow". It was a BD Diesel kit. I still have the factory filter housing and the pressure is being read at the injection pump inlet. Thank you in advance.

I think I was more vague yet I meant lift of the cam lobe. I also have a 12 valve OEM cam here and the profile is kinda interesting. The intake lobe is very sharp as in it peaks then goes back down whereas the exhaust valve is very rounded so it kinda lingers at the peak and neanders back down. I am not sure if that has anything to do with it, sure don't know what a 24V cam looks like.

I think I was more vague yet I meant lift of the cam lobe. I also have a 12 valve OEM cam here and the profile is kinda interesting. The intake lobe is very sharp as in it peaks then goes back down whereas the exhaust valve is very rounded so it kinda lingers at the peak and neanders back down. I am not sure if that has anything to do with it, sure don't know what a 24V cam looks like.

I would say that is how I would descripe the Colt. I don't remember the profile of the old cam, it is long gone. I do remember the intake was sharper than the exhaust but can't say more than that. Unfortunately this is the only picture I have of the stock 24 valve cam. Happy hour started shortly after a long day of tear down.

[TABLE]

[TR]

[TD=colspan: 7]Cummins 5.9 and 4BT Cams Cam Specs

[/TD]

[/TR]

[TR]

[TD][/TD]

[TD][/TD]

[TD=colspan: 2]Duration

[/TD]

[TD=align: right]Cam

[/TD]

[TD=align: right]Lobe

[/TD]

[TD]

ROCKER RATIOS:

12V - 1.75/1 INT/EXH

24V - INT 1.5/1 EXH 1.4/1

[/TD]

[/TR]

[TR]

[TD]Prof. I.D.#

[/TD]

[TD][/TD]

[TD=align: right]@ .050

[/TD]

[TD=align: right]ADV.

[/TD]

[TD=align: right]Lift

[/TD]

[TD=align: right]Sep

[/TD]

[/TR]

[TR]

[TD][/TD]

[TD]INT.

[/TD]

[TD]

159°

[/TD]

[TD][/TD]

[TD]

0.235

[/TD]

[TD]

102.0

[/TD]

[TD]Stock 2nd Generation 12V 1994-1998.5

[/TD]

[/TR]

[TR]

[TD][/TD]

[TD]EXH.

[/TD]

[TD]

204°

[/TD]

[TD][/TD]

[TD]

0.263

[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD][/TD]

[TD]INT.

[/TD]

[TD]

159°

[/TD]

[TD][/TD]

[TD]

0.235

[/TD]

[TD]

107.5

[/TD]

[TD]Stock 2nd Generation 24V 1998.5-2002

[/TD]

[/TR]

[TR]

[TD][/TD]

[TD]EXH.

[/TD]

[TD]

206°

[/TD]

[TD][/TD]

[TD]

0.297

[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD][/TD]

[TD]INT.

[/TD]

[TD]

163°

[/TD]

[TD][/TD]

[TD]

0.237

[/TD]

[TD]

98.5

[/TD]

[TD]Stock 24V C.R. 2003-2007

[/TD]

[/TR]

[TR]

[TD][/TD]

[TD]EXH.

[/TD]

[TD]

191°

[/TD]

[TD][/TD]

[TD]

0.299

[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]Stage 1

[/TD]

[TD]INT.

[/TD]

[TD]

175°

[/TD]

[TD][/TD]

[TD]

0.251

[/TD]

[TD]

103.0

[/TD]

[TD]Hi Torque, bottom end fuel economy cam.

[/TD]

[/TR]

[TR]

[TD] C.332.S

[/TD]

[TD]EXH.

[/TD]

[TD]

206°

[/TD]

[TD][/TD]

[TD]

0.297

[/TD]

[TD][/TD]

[TD]

DISCONTINUED

[/TD]

[/TR]

[TR]

[TD]Stage 2

[/TD]

[TD]INT.

[/TD]

[TD]

175°

[/TD]

[TD][/TD]

[TD]

0.251

[/TD]

[TD]

104.0

[/TD]

[TD]New torquer cam. Better exhaust flow and better fuel economy.

[/TD]

[/TR]

[TR]

[TD] C.341.S

[/TD]

[TD]EXH.

[/TD]

[TD]

210°

[/TD]

[TD][/TD]

[TD]

0.307

[/TD]

[TD][/TD]

[/TR]

[/TABLE]

I "borrowed" this from Colt Cams for the profiles. On a side note I did not know they stopped selling the stage 1.

Man that garage is just filled with neat stuff! I just can't figure out how the thing can be most noticable at idle, when the engine is already running really lean. Up high is where it would be more noticable I would think because thats where the engine starts to really rely on flow. I am betting it has something to do with the profile making the valves open at a different rate. I'd really like to know for sure. I think with the thought of different profiles in mind I may have something for google to get to work on. I couldn't really get anywhere with "swap cams noise changes"

Thank you at the time we had multiple projects going on at the same time and the garage was littered with parts. I went back and reread the posts and it was my bad for some reason I thought lift pump. I was thinking maybe a FASS or Airdog that separate air out of the fuel could quite down injectors and smooth out the idle. I think I will make a video once. My friend has smart phone so I will see if we can make a quality video. I hope to have something by the end of the week. I will let you know.