1986 big cam cummins lovers please click here

Well which do you have high or low flow?

Are you able to get the CPL number from the engine?

 

Join the Cummins 855 facebook page.

 

BEEEEautiful!! The K-100 was top of the line,,,for cabovers. You couldn't have picked a better truck,,,for a cabover. Never knew the difference in the numbers, 3 or 4. I think most of the Cummins I drove, were the BC 3's, but didn't matter. It wasn't like the BC4's would beat a Cat anyway, but for reliability, BC Cummins always hauled the mail for me. Lose the 8LL. I drove a dump truck with one, was the most useless tranmission I ever drove. Since a Cummins isn't really happy with a 10 speed, although most Cummins powered trucks had them, go with the 13, and if you have the cash, taller gears, 3:55's seem a good balance. It's refreshing as heck to see a young guy with a K-100. Great trucks, if it has air ride, that is. Spring ride,,,not so much.

 

This may help you some.
http://ww2.justanswer.com/uploads/J...o_Build_a_High_Performance_Cummins_Diesel.pdf

 

Being a 86 model it should be a Big Cam 4. Should be a tag with a CPL number on the left front of the engine. If the tag is missing look just below the head gasket at the rear left corner of the block, will be a raised area there with the serial number stamped in it.

I myself run a 1986 BC4, tag says it's a 315.... mine is a might more .

As mentioned above there is a FB page titled Cummins 855 enthusiast that has some very good knowledgeable heads.

Good engines but like anything else.... has its limitations.

 

Found out in 1987, the B,C 315 I ran in a Tri-Axle Dump truck. Would fly when I changed out the Button and spring.
Buddy of mine that is good on the old engines. Told me the 315's were the same as a 400. Same pistons and all. Just less fuel, so after that change. That truck ran great grossing 74,000 lbs. Then pulled the bed and third axle off it. Mounted a 5th wheel, and hauled logs with it. Even grossing 100,000 it would pull. After I got out of it, The next guy, melted it down. He had no ideal what the ETG gauge was for.

 

Here's a page with more info on your engine.
Cummins Big Cam engine history with CPL notes

 

Yes that Pyrometer is a major key in protecting the engine when it is HOT .
Sadly some fail to use it, and things go south lol.

400 has lower compression pistons than the 315. 400 times at .070 and 315 at .065 if memory is correct.

Pretty sure 400 & 365 share the same pistons, and most 315, 350, 300 and such share the same piston. Although there is a 350 hp that runs a 14.5 compression piston versus the normal 15.0 if memory serves right. I will have to look in my book out in the garage. It's been a while lol.

My engine is running the same turbo as a 525 red top N14, stock 400 injectors call for 176 injectors, my engine is running 220 injectors. It doesn't pull like a 315 or a 400 . @wore out and @Logan76 can tell you what my engine sounds like, it is a little different lol.

The big pump which I took off was calibrated for a 475 + 100% with the throttle shaft drilled out larger, and has KT and VT Cummins parts in it. It made a 565 ISX engine look like a 6-71 2 stroke Detroit .