Big cam III in a 5ton?

[WillWagner]

RE: Re: RE: engine swap questions

5 1/2 in. bore x 6 in stroke. A 2100 governed engine will trun 2500 rpm at high idle, no/low load. They will run at 2400 rpm, but the only thing you'll get besides 9 mph more is real bad mileage. I have had vehicles on the dyno with 855s in them that turned 3000 + rpm. They get real quiet at around 2700!

 

[Bigmillman]

RE: Re: RE: engine swap questions

Sorry. I have to agree with the others. Don't mess with a good thing. If you are truelly trying to do more, maybe a different truck is in order. I would hate to see you munch up your pocketbook when you might be better off expanding your fleet by one.

 

[steelsoldiers]

RE: Re: RE: engine swap questions

For higher road speed and more out of the box power options, you could go with a 939A2. With that series you get an 8.3CTA, which already has power parts for sale on the net including bigger injectors and fuel plates. TST makes some power items for them. You also get straight air brakes and that would be a huge plus with the increased road speed and weight. They will run 65 MPH all day with the 14R20 super singles. The big tires and CTIS (IF it works) would be a plus in the sand. My CTIS worked just fine and would air the tires down to 10 PSI in SAND mode. I was definitely in the minority to have a functional CTIS though. Even a 939A1 truck would be an improvement. The Allsion 5-spd auto does a much better job of keeping the NHC250 in its power-band. No big jump between 3rd and 4th any more!

 

[madsam]

RE: Re: RE: engine swap questions

I have a question for anyone who has seen these engines blow? what is the top 5 failures one of these 855s go boom? Is is piston melt down, or rod failure or valve issues?

 

[madsam]

Re: RE: Re: RE: engine swap questions

They get real quiet at around 2700!

Does that = broke?

 

[Bulldog06]

How close are the engine mounts if you replace the Cummins 250 small cam in the M813's with a 855 big cam. I reviewed the above notes but did not see a response from anyone that had actually made this swap.

 

[G744]

A governor is your friend, not a 'flexible' device to sate your 'instant gratification' desires.

Don't monkey with it.

The only time they will let you down is going downhill in a gear that seriously overspeeds your engine and the result will usually catch up to you quickly.

Dennis

 

[simp5782]

How close are the engine mounts if you replace the Cummins 250 small cam in the M813's with a 855 big cam. I reviewed the above notes but did not see a response from anyone that had actually made this swap.

You need to cut the cross member and weld in a flat piece of metal for the big cam mount to sit on top of.