NHC250 and timing

[jwaller]

what role does timing play in a diesel engine?

I'm not new to tuning and such but I got to thinking and thats what usually gets me in trouble but I can't stop thinking about how to get some more power from my 818.

here are some what if's and I hope some on here can help.

I am getting 1200 deg under load and I'm told that is the max temp I want to see with this motor.

??? can I advance or retard the timing some so as I can get more fuel in and make more power??? or will that not make any difference.

and for those that want to answer and not tell me to look it up; how do I set/check the timing and what should it be set at?

 

[WillWagner]

No lookin' that up here. The manuals do not go into that detail. The base timing is done thru a key in the nose of the cam. Fine timing is done thru the gaskets on the cam boxes. Unless you have lots of white smoke at start up, don't mess with the timing. If you want HP, you only need to turn the throttle shaft screw. If you want RPM, put a button in it. Keep in mind, the NHC is NON piston cooled. Juice it up and you WILL hang a piston. However, late blocks could have piston cooler block offs, meaning, the cooling rifle has plugs that look like PC nozzles, but aren't. They are only blanks, so you can buy a set of PC nozzles and give it a tad more fuel. The only way to tell..if it looks like there are nozzles in there...is to take one out. You will need new o-rings to re-install it
HTH, Will

 

[AMGeneral]

Ok,The Cummins PT type system is based on the pressure/time principle,(hence the PT).The pump actually for lack of a better description is just a pressure pump/governer,the actual timing for the fuel delivery is accomplished by the camshaft providing sufficent pressure to atomize the fuel entering each individual injector via pushrod and rocker arm mechanically actuating the injector at the approiate time.So the only way to advance or retard the timing is to advance or retard the camshaft in relation to the crankshaft.Not sure if that's possible in stock form and the engine stay together.

 

[jwaller]

ok. so this is another dead end. thanks for the info guys.

I for the life of me just dont understand how you can have an engine this large(CI's) and not make any more power.

FWIW I'm pretty sure I have this thing running about as good as any 250 out there. it makes slight black smoke and runs very strong when bobtailing. it's just a dog when towing the load.

 

[WillWagner]

Remember, it's non turboed and limited by the no piston cooling issue. You could make bunch of power...for a very limited time then hang the pistons. The big cam and small cam are the same dimensions. A big cam will fit, just groom the exhaust and intake over, then you could make more power w/o piston damage.

 

[jwaller]

well thats what I am trying to do. make some power without going over 1200 deg egt. I know if you go over it you will damage the motor. I'm not sure what you mean by groom the exhaust and intake over. do you mean porting and polishing or what?

I'm all for swapping cams, somebody just tell me where to get one.


I just finished reading some info in the 260-34 on injector timing and it's different to say the least and not adjustable really. not like the multi or the gas motors I'm used to working with