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CAT 1693 - Specs and the story on them?

201K views 48 replies 24 participants last post by  midnitetrucker7 
#1 ·
I have been searching around for info on the old CAT 1693. What are the specs, weaknesses, etc. All I know is that it is a predecessor to the 3406. Any info or comments are appreciated. Thanks.
 
#2 ·
Bottom is same as the 06. 893CID, same rods and crank, pre-cup button top pistons, single hole piss type nozzle in pre-cup chamber, etc... The dif is quite substantial on the top. Twin overhead cams, rear drive gears, Airesearch T1810 bolt flange turbo (loud and strong, but not for long) etc... The upside is you'll never lose the bottom end. Pre-cups don't load the crank like DI's. The downside is the leaking and cracking rocker boxes, the "quill drive" to the cams twists (but on the upside the quill drive can be cut and re-welded to any degree of advance to the cams), the air compressor mount, leaking front and rear covers, the ratchet heads for the valve sets strip, no one to work on em, drinks fuel, obsolete in finding castings and parts, etc... The 425's were pretty cool. The 325's kinda sucked. Tons of torq tho. Good luck bud...T
 
#3 ·
Oh, forgot the story. Sorry. History is it was the first big bore Cat truck motor, which was a redesigned uprate from the D343 dozer motor. Worked OK but had a lot of comebacks for leaks and a few big exploders. The biggest downside at the time was the addition of the Brakesaver, which ate everything. Then in the mid 70's Cat brought in Dennis Porter and a couple others to redesign for the Heavy Truck class, hence the advent of the 3406PC. Had a couple bugs, worked them out, the rest is history...T
 
#4 ·
Thanks for the info. So you think a 3406B or C is the best? I am sorta split between the Cat and Cummins 855's of various flavors being a casual spectator and potential future owner.
 
#6 ·
CAT for sure the 3406B i got in my Pete pulls like crazy(after some minor adjustments, thanks Tony), I haven't found a truck that will out pull it yet.
 
#8 · (Edited by Moderator)
Thanks, just looking at that I remember the top turbo mount over the valve covers.. That is some history there... (y)
 
#9 ·
I know of a guy that has an old Pete with a 1693 in it. It runs strong, and he pulls is some. But man do they sound like they are gonna fall apart, (rattle and knock.)
 
#10 ·
I have heard some old guys talk and say that if they are not rattling thats when yo need to start worrying. they do have the some bore and stoke as the 3406 but the block is nowhere close to being the same. My old man says when they used to throw rods, they welded plates over them and keep running them. It is a unique motor you can change rods in them with out pulling the pan off of them. I was an amazing engine due to the fact that the tech. was far ahead of its time. if you wander why i know about them i have 3 of them, two 425s and one 325.
 
#11 ·
855 all day anyday cheap power.
 
#12 ·
The point of the thread isnt to debate which motor is better he is just wondering what the story of the 1693 is, not to say that its better than a cummins. The four and a quarter cat, is that a 1693 or a 3406? I always hear how good they were but was just wondering which model people are refering to.
 
#13 ·
Really didn't have anything to do with Cummins. I wasn't familiar with this CAT and couldn't find much on the net about it. It sounds like a good motor, a bit ahead of it's time but not direct injection. Sort of like the KT cummins in some ways in how it served the trucking industry. I have heard elsewhere that they are pretty durable and easy on bearings.
 
#14 ·
Chris88 said:
The point of the thread isnt to debate which motor is better he is just wondering what the story of the 1693 is, not to say that its better than a cummins. The four and a quarter cat, is that a 1693 or a 3406? I always hear how good they were but was just wondering which model people are refering to.

Most people are probably refering to the 3406, atleast when most of the guys i am around are talking Four and a quarter they are talking 3406
 
#15 ·
I would say that when most people are talking about 425 Cats they are refering to the 3406B air to air motor from the mid 80's and newer, and like you said information is hard to find on the 1693 mostly due to the fact that there arent many left running. Also the last production year that the motor was offered was 1976, again another reason it is hard to find info.
 
#17 · (Edited by Moderator)
They were cats first leap into the OTR truck market. IT was a bit before my time. I have ridden in a truck powered by a 1693 and it pulled strong. But when he fired it up and it settled down to an idle I waited a couple of seconds before going near it. I thought it was going to rattle apart!

Like said previously, when the get quiet that's when you have to worry! Now a day they pretty much live along side the 3408's in the fact that if there running they should be kept running because there a unique part of the history of the modern Semi truck and diesel power in general.

But there fuel sucking pigs and parts are rare and spendy! They Smoke pretty good and can be turned up to really lay power to the ground. But they can, do, and will break when pushed to there limits.

If i had the space to keep one inside and the $$$ to restore them and treat them right I would definitely have one as a toy. Would I run one down the highway ever day to make a living? Definitely not. Just to many better options out there that are cheaper to maintain, easier/cheaper to repair, and get WAY better mileage. And in OTR trucking MPG = $$$
 
#18 ·
kblackav8or said:
What can you do to upgrade one from 325hp?
The main difference between the 325 and 425 was the air-charge cooler, the 425 had one the 325 didnt. A 325 can be made to run with a stock 425 on fuel alone, not sure how they do it but it takes somebody that has been around one before to know exactly what screws to turn.
 
#19 ·
They really are sort of exotic. Got a look at one in person today. DOHC, 4 valves per, turbocharged, 14.7 liter or 893 CID. They are big and unique sounding. I am not against Cummins in any way but these are pretty cool. It is too bad they are somewhat fragile if you abuse them.
 
#20 ·
The 1693 was kind of a prelude to the 3406. They had some good ideas just needed time to refine them. I know the dealer here had to pull a few of them out and change them for Cummins to keep the big customers happy. The early 70’s model 359 Peterbilts had inboard steering boxes so that was a project if I remember right.
 
#21 ·
Just started tearing into one of my 1693s, after working on this thing I think a toddler could tear it apart and put it back together, it is very simple. I will try and get some pics soon.
 
#22 · (Edited by Moderator)
#24 ·
What year did they stop puttin the 1693 in trucks? My buddys buyin a 74 pete with a cat and thats as much as i know, would that be a 1693 or 3406pc?
 
#25 ·
Not 100% sure, but IIRC, the 3406 came out in '77 or '78.
 
#26 ·
Last year was 76 both the 1693 and 3406 were offered 77 was strictly 3406. Thaat 74 Pete might be a 1693 but it also could be a repower, I would have to see some pics of the motor to be sure.
 
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