how good are older cummins big cam engines?

Just don't let it Jake in the high RPM's. 1600 is lots otherwise you may break a head bolt.

 

I think the 475 twin turbo was a rare engine to begin with, compared to the 400 and even the 444. So finding info might be difficult.

 

FWIW, the first engine to get a "jake" brake was a non turbo N series engine back when Clessie Cummins invented it and was testing it.

 

BossHogg: When I worked at Cummins in Indy in 84-86 when the Big Cams first came out. The Big Cam's were a good engine if you kept up on valve adjustments if not it would wipeout a Camshaft and bearing changes were critical because of bearing composition. They had a problem with head gaskets leaking because of the upper counter bores. Otherwise I could get 400 HP Cummins to pull 365HP at the wheels with factory settings and they got 5-5 1/2 MPG at that time.

 

I am building a Big Cam III using 20/40 lower press fit liners, 14.5 Dual Ni Resist pistons and .77 cam timing. It seems that the 14 to one pistons are no longer available. Injectors flowed to 200, large gear fuel pump and turbo round out the setup.

The engine if rebuilt correctly will be better than it was when originally manufactured.

 

Is this forum still alive?

 

I'd say it is now LOL....

 

Great engine. I'd take it over anything. Also can be greatly upgraded for power. I've driven 350, and 400 big cam. Love them.