cummins bc vs. cat

Only the later years of the Big Cam were low flow if my memory is right. I still remember the first low flow setup I ever seen, Pop bought a nearly new 1987 Freightshaker with a 444 in it, odd looking Varmit compared to what I normally drove.
Example... I'm at this time working on a Big Cam IV with low flow, it is a 1986 model engine. If my memory is correct all Big Cam 4's were low flow, I could be wrong. But I'm converting it all over to a high flow setup and putting the N14 air to air on it.

 

Sounds about right. I don't believe the BC3's were low flow but I'm pretty sure all the 4's were.

 

I have '86 BC3 has the high flow cooling system

 

Sorry it is a '85

 

The low flow is an abomination, they only used it on truck engines, every industrial engine I have came across uses a setup like the BC1-3.

The 444s were trick ponies, chrome crossover tube and aluminum rocker covers set them apart with the black paint.

 

I think 84 or 85 was first year for the low flow....could be wrong. The engine I'm building dated 1-86, so it will be a big cam 4 with high flow cooling and air to air when I'm done.

 

I seem to recall the issue with the low flow was it had more of tendancy to overheat than the high flow.

 

Big Cam 4's were the only low flow engines. All previous were high flow. Low flow works fine generally at stock power levels as long as the system is in good shape. Turn it up and it will overheat. That's the only bad thing about the BC4s, other than that those motors were greatly improved over the previous Big Cams.
I've got a Big Cam 1 now and previously had a 3406C that was all mechanical. After having both I prefer the Cat. Both motors were 350s turned up to 400 and I can't really tell any difference in power between the two. My Cat was geared way too low which hurt mileage and power. The Cats don't like to turn RPMs and the Cummins love the RPMs. Here's my opinions on the two motors based on my experiences.
Cat:
Motor is MUCH quieter and smoother.
Will crank at any temperature as long as it will turn over.
Didn't get as good of mileage as my Cummins, but probably due to gearing.
Jake brake was totally useless, even after a rebuild. It did nothing.
Parts are very expensive, at least from Cat.
4:10 gear is way too low. I would never go lower than 3:55 with these motors.

Cummins:
Very noisy, rattly motor compared to the CAT. Motor noise is much louder inside the cab.
Exhaust noise is at least 3 times as loud. Whether this is good or bad depends on the driver lol.
Very cold natured. Keep it plugged in or a can of ether handy.
Jake brake is awesome. I didn't know how good one could be until this truck.
3:73 gear seems perfect for this motor.
Cannot use a throttle stop to hold the RPMs up. The PT fuel system is too erratic and it will never stay where you set it. Major pain when it comes time to warm it up in the mornings or build air up quickly.
Exhaust temps are higher on this motor with much less smoke than my Cat had. I'm guessing its because this motor doesn't have an intercooler.

I don't think you'd go wrong with either motor. I prefer the Cat but am definitely happy with the Cummins.

Justin