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Member
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Discussion Starter #1
Hey guys,

I am in a bit of a pickle. I bought an 86 Kenworth k100 and it has the Big Cam 400 Cummins. Before I dump money into this truck and fix it up, a friend of mine has offered to sell me his 87 Kenworth k100 with a 3406B Cat. The Cat has been inframed 75000 miles ago. From the reading I have done on here, it seems people on here either love the Big Cam motors or hate them.

So what are the pros and cons of each motor? I want to be able to daily use this truck if I so wish.

Thanks
Matt
 

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Big Cam Power!!!!!
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484 Posts
Hey guys,

I am in a bit of a pickle. I bought an 86 Kenworth k100 and it has the Big Cam 400 Cummins. Before I dump money into this truck and fix it up, a friend of mine has offered to sell me his 87 Kenworth k100 with a 3406B Cat. The Cat has been inframed 75000 miles ago. From the reading I have done on here, it seems people on here either love the Big Cam motors or hate them.

So what are the pros and cons of each motor? I want to be able to daily use this truck if I so wish.

Thanks
Matt
Both are good motors, you could be buying your friends headache, Cats are more expensive to work on Cummins are somewhat less expensive to work on both are good motors again can't go wrong with either one even tho I'm a Cummins man
 
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Senior Member
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What LOG HAULER says is true both good engines, both behave differently the cat makes its torque down low and is a smooth quiet engine. the cat starts up clean for the most part and high idle can be set without worry about it bouncing off the governor while you go back and grab your coffe cup.

The cummins can be cheaper to work on. jakes well needs to spin a little faster to do the same job. if it's not step timed it may be smoky on start up until it has warmed especially if turned up. doesn't start quite as well in cold weather. can be a real pain to get to hold a stable hi idle for warm up

If you can drive both trucks for at least half an hour I would recomend it, see which one suits your driving style. Glad you are buying up the cab overs , leaves the conventionals for me:woohoo
 

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248 Posts
The cat is.gonna have better resale at least in my area. I played with both a fair bit and in my opinion the cat is gonna have a much better torque curve than the big cam. Though I did get a little better mileage out of the cummins. If you ever plan on hopping it up in my case the cat held up much better. These two engines were in the same truck. I pulled a four axle container chassis grossing 102,000 the cat defiantly done a better job. Both can be a reliable engine with proper maintenance. I had problems with the thrust bearing in the big cam. It did have the large gear pump on it and oversized injectors in it. Also played around with the variable timing on it, but never thought I ever had it set right. It was a terrific engine for me, went 800,000 and I was always playing with it trying to squeeze a little more out of. I finally put a hole in a piston. But with that many miles on it and as hopped up as it was I figure that the last 300,000 miles it was on borrowed time anyway. If its a low flow cooling system I highly recommend converting it to a high flow.system if your gonna hop it up at all
 

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As it has been said previously both are good motors. When you drive both to compare before making a decision make sure you drive each properly in their respective powerbands. Cummins love to rev (1600-2100+)
 
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