Big Cam 400

**Chris M.** · 04.07.2012

Okay so i am not exactly new to the scene but i am slightly stumped. Im looking to buy another truck that has a Big cam 400 cummins. The truck is 80s 359 and a 9 speed. I dont know what the diffs are. I am just a little sceptical on this motor trans combo. Some general input would help. I haul western-midwest states pulling a reefer and maybe jumping into the curtain van world. I do go up White Bird in Idaho a lot so (way cooler than Cabbage and Sherman) pulling power is fairly important. I understand that this in not a fuel efficent motor but general mpg. Im not replacing this truck for the other, just another truck for me. There is tons of information on this motor which is great but most of it is on mods and trick stuff.

**DieselDummy** · 04.08.2012

Biggest thing you wanna get is the engine serial number, this will tell you alot about the motor. Another is the CPL# which you will find out when looking up serial#. Ususally the CPL will also be stamped on the pump tag on the upper left.

**DieselDummy** · 04.08.2012

**DieselDummy** · 04.08.2012

Big Cam 400-imageuploadedbytapatalk1333885185.683371.jpg

Pump tag

Big Cam 400-imageuploadedbytapatalk1333885209.943840.jpg

Engine serial number is stamped on block, if tag on front cover is gone.

You ca sign up on Cummins quick serve for a free account and look at up to 5 serial numbers before you pay.

**rjones56** · 04.08.2012

Run under normal conditions-probably 5 t0 5.5 mpg.

**Chris M.** · 04.08.2012

Awesome thanks for the replys. I should be able to get the numbers later today along with the pump

**ohio_redneck75** · 04.08.2012

i have a 400 bc in my 89 volvo lots of motor mods done to it. the average mpg i have been getting is 6 to 6.5. its a higher rpm motor than the newer cummins 1700 to 2200 is the sweet spot with mine

**DieselDummy** · 04.08.2012

Just finished up my dual feed line and fuel pressure gauge.

**Crusty** · 04.08.2012

Long ago in a galaxy far away there were cummins diesels fondly refered to as 'shiny 290's'.These motors were high rpm motors that shifted around 2700 rpm. Not a typo. Twenty seven hundred. They got around 4 mpg. Mack low rpm models around the same HP/torque were getting TWICE that. (cut back and dogged out, but they did it) Not to be out done, Cummins cane out with their 'big cam' series with 9 speeds. Much lower power band = fuel savings. That is the extreamly short answer.