3406B 400HP - Diesel Forum

brahamfireman · 11-07-2006, 10:36 PM

what all is done to the 3406B to differentiate from the 400HP and the 425HP? all I ever see is the 425 HP never the 400, well the truck I am looking at is a 400, upgraded from [img]/ubbthreads/images/graemlins/shrug.gif[/img] 350??? 375??? I dont know just said "upgraded to 400HP" on the rebuild sheet the guy gave me.

I know you can turn the fuel screw or plate whichever that B model has, I dont recall at the time, either way 400 just won't cut it [img]/ubbthreads/images/graemlins/biggrin.gif[/img] [img]/ubbthreads/images/graemlins/biggrin.gif[/img]

Diesel Rod

ProDriver18 · 11-08-2006, 02:21 AM

I don't really know what the difference is. But, in the late 80s I drove a long '85 Freightliner conventional with the 400HP 3406B, 15 speed with 3:90 rears on tall rubber. I pulled a 42' hopper bottom and hauled grain and feed products. The pump had been bumped up by a Cat mechanic and that truck had no idea of what a load was. It didn't care how much you put on it. It was like, don't worry about the mule, just load the wagon. I embarrassed more than a couple of 425 Cats and 444 Cummins with it which were the big motors of the day.

dondiesel444 · 11-08-2006, 06:39 AM

I had a 3406B 425 hp, now I have a 3406C 350 hp. the difference is night and day, the 350 was a complete dog when I got it. I turned the fuel screw and the truck has more power, but still not as much as a stock 425 hp. I am guessing I have close to 400 hp, but probably not that much. my Dad has a 425 hp 3406C in his truck, and the noticable differences are his turbo is wastgated and twice the size of mine (mine is NOT wastgated) and his intercooler is also twice the size of mine. those are the only external differences I can see, I think the pistons and valve train are the same, but I am guessing the injection pump timing and specs are completely different.

I wish I had 425 to start with....I miss my old B motor.

04HDF250 · 11-08-2006, 10:09 PM

Depending on S/N break range, compression ratio could be 15.2 or 15.6, nozzles might be different which would mean different fuel settings. It all depends on which S/N's you are dealing with. 7FB, 3ZJ, 4MG...... lots of variables in those old mechanicals.

brahamfireman · 11-08-2006, 10:12 PM

well right now all I have is the vin, no engine number but after sunday I will have pics and most likely the number for ya.

Diesel Rod

grounder · 11-09-2006, 10:09 PM

There are also different plungers & Barrels in the Pump.It all depends on what it is.Going overboard on the Fuel or Timing Adv. will Burn it down if you are Not careful.I have seen more than a few pistons split across from a Hole being Burnt through the crown.Just a word of caution.

rvannatta · 11-10-2006, 01:06 AM

Part of the issue with the 3406B at 425 was that it was a little much in torque for the available transmissions of the day. the word on our '89 binder is that the engine is tweaked a bit at the factory to reduce the max torque to meet the max torque of the 18 speed behind it. At that time the engines had sort of gotten ahead of the transmissions.

This is why the classic 5 and a 4 suddenly disappeared in the 80's
is that the boxes wouldn't handle the torque rise ......

Something that wasnever an issue when the engine of the day was a DD8-V71 or a DD 2 cycle anything

dondiesel444 · 11-10-2006, 06:17 AM

I have tuned my fuel screws out on my 3406c 350 hp, it's definaly making more power but my gauge readings are 25 psi and 800 degrees max. I know this motor must have more b/c it's not even close to running hot. it puffs a little smoke when I get on it, but nothing like a turned up B motor. I wish someone knew what I could do to get more power out of it, ANYONE??!?!!?!

brahamfireman · 11-18-2006, 07:14 PM

[ QUOTE ]
Depending on S/N break range, compression ratio could be 15.2 or 15.6, nozzles might be different which would mean different fuel settings. It all depends on which S/N's you are dealing with. 7FB, 3ZJ, 4MG...... lots of variables in those old mechanicals.

[/ QUOTE ]

well I got it home last weekend, Engine Serial Number 7FB76166. found the plate that hinds the mithical screw [img]/ubbthreads/images/graemlins/biggrin.gif[/img] just have not pulled a load with it yet kinda want to see how it pulls before I giver the fuel.

Diesel Rod

binderman78 · 11-18-2006, 07:38 PM

[ QUOTE ]
I have tuned my fuel screws out on my 3406c 350 hp, it's definaly making more power but my gauge readings are 25 psi and 800 degrees max. I know this motor must have more b/c it's not even close to running hot. it puffs a little smoke when I get on it, but nothing like a turned up B motor. I wish someone knew what I could do to get more power out of it, ANYONE??!?!!?!

[/ QUOTE ]take the c model pump off and put a b model pump on it. you willhave to go to a mechanical linkage but it woll make a truck out of it [img]/ubbthreads/images/graemlins/smokin.gif[/img]

dondiesel444 · 11-18-2006, 09:16 PM

what do you mean mechanical linkage? you mean throttle linkage? my truck already has mechanical throttle pedal linkage. actually the pump on this C motor looks very similar if not identical to the B pump on my old truck. I guess the internals are different between the pumps??

binderman78 · 11-18-2006, 09:21 PM

the c model im thinking of has a tps no mech throttle linkage it was cats piss poor attempt of going elec. the precursor of the e model

catdiesel0631 · 11-19-2006, 01:44 PM

You are refering to a "PEEC" engine....totally different.

lets get some facts strait here.

YEs this engine was ORGIGINALLY a 357hp engine par dyno from the factory---I looked up the spec on your engine.

YES it makes a WHOPPING 1097ft/lbs of torque [img]/ubbthreads/images/graemlins/smile.gif[/img]

And moreover this engine had or still has a factory 1800rpm governor spring. The spring needs to be changed out internally in order to get more RPM's outa the beast.

WITHOUT looking, some of the hard parts of the engine that I think are different

....Pistons
....Turbo
....guts of the fuel pump
....and most importantly you dont have a spacer plate between the block and the oil pan. USde for higher torque/hp rated engines to g=keep the block from cracking. Easy adder

Easy things you can do to fix this..

Bump the timing up alittle on it to give it some PEP. Turn the fuel screw in a few rounds and slap a larger turbo on there.

Hard to say whether or not some of this stuff has been done or not but that will get you in the right direction [img]/ubbthreads/images/graemlins/cool.gif[/img]

binderman78 · 11-19-2006, 06:54 PM

thanks for correcting me I was wondering when you would show up its been a while since i worked on one.

brahamfireman · 11-21-2006, 11:03 PM

[ QUOTE ]
lets get some facts strait here.

YEs this engine was ORGIGINALLY a 357hp engine par dyno from the factory---I looked up the spec on your engine.

YES it makes a WHOPPING 1097ft/lbs of torque [img]/ubbthreads/images/graemlins/smile.gif[/img]

And moreover this engine had or still has a factory 1800rpm governor spring. The spring needs to be changed out internally in order to get more RPM's outa the beast.

WITHOUT looking, some of the hard parts of the engine that I think are different

....Pistons
....Turbo
....guts of the fuel pump
....and most importantly you dont have a spacer plate between the block and the oil pan. USde for higher torque/hp rated engines to g=keep the block from cracking. Easy adder

Easy things you can do to fix this..

Bump the timing up alittle on it to give it some PEP. Turn the fuel screw in a few rounds and slap a larger turbo on there.

Hard to say whether or not some of this stuff has been done or not but that will get you in the right direction [img]/ubbthreads/images/graemlins/cool.gif[/img]

[/ QUOTE ]

I take it this is for me, in replay to my original question?

If so thanks much and would I have to go straigh to Cat to get different Gov Springs and the Pan spacer???? or can I find em else where?

Diesel Rod