Engine Transplant

[Eagle Andy]

Hey Guys, I might have opportunity to put a cat 3406 model c in my Eagle. I have a 740 allision 4 speed in now with 8V92 TA any thoughts on the swap.

[TomC]

I have the Cat 3406B 400hp jacket water aftercooled in my truck conversion with the HT740 and 3.55 rears on 11R-24.5. Runs well and I believe that Cat 3406 (B or C) mechanical injected engine is quite possibly the most reliable engine ever made. If you can fit it in (it is tall), would make a great bus engine and you'd probably get 1-3 better mpg. Good Luck, TomC

[luvrbus]

If it is a electronic 3406C with out the donor rig you will have your work cut out for you charge air piping can be a little problem unless you go to a smaller radiator and mount it beside the radiator.

You should get a lot of advice from Eagle owners there is probably 2 times the Eagle bus owners with Cat engines than with the 60 series or Cummins I love on yellow   

[Eagle Andy]

Can I use my 3:36 gears with that set up ?

[wg4t50]

Sure, the 3.36 or even a 3.08 depending on the tranny and final ratio, a 4 speed direct, use the 3.08, if the 4000 series with 2 overdrives, use 3.94 or 3.73.
lots of play area.

[luvrbus]

The 3:36 is the highest for a Eagle with a drop box if you use a 4000 or any other world transmission you need to go down and 4:11 is the best you can get with the drop box it works 

You can do like Sonnie and Wayne and convert to a tag arrangement Sonnie uses a 2:98 with the 740 behind his 3406 or you can go with a Eaton auto like Jim and others with Eagles for gearing

If that is a mechanical 3406 C stay with the 740 Bryon uses a 740 behind his series 60 and so does Pratt with his electronic Cummins both run 3:33 gears

[Eagle Andy]

Well I would use the 740 I already have maybe freshin it up, I would like to use all the same running gear and just do the engine swap. refab mounts and reinforce the cradle if needed.

[TomC]

I don't like to run fast, so with my 3.55 and 11R-24.5 (476rpm), with the HT740's direct drive in 4th, my cruise RPM is 55 @ 1549 (really good fuel mileage); 60 @ 1690; 65 @ 1830 (can do this all day long since 1800 is the continuous rpm rating of this [and most other big truck/bus engines] engine); 70 @ 1971; 75 @ 2112; 80 @ 2253; and top speed of 85 @ 2393. My truck weighs about 32,000lbs now and I like the performance. I'm not changing the rear end ratio. Good Luck, TomC

[Geoff]

Whats wrong with the 8V92TA?  I have a 6V92TA and love it; and I don't have money burning a hole in my pocket for upgrading my bragging rights.

Not worth the change IMO, or is this an Eagle thing?

--Geoff

[TomC]

Unlike you, Geoff, we don't know how to work on the 2 stroke engines-and there are very few good mechanics out there that can work on them. This is the main reason I haven't taken my bus to Alaska-even though virtually everything mechanically on the bus is rebuilt. Come the time when my truck with the Cat 3406B is ready to go, and the first place I'll head to in summer (which summer, I don't know yet) will be Alaska since every engine mechanic still knows how to work on a Caterpillar.  Good Luck, TomC

[TomC]

In fact, most everything on the Caterpillar 3406, I can do myself. The Detroit 2 strokes are just plainly weird with all their idiosyncracies in how to set the injection height, injection timing tool, set the rack, make sure the clearance on the rocker arm is correct, set the governor engine speed limit, set the governor idle speed, set the idle control (forgot the correct term to keep the engine from rolling when idling), make sure the transfer pump has enough pressure, etc. On the Caterpillar-install a new injection pump with the timing marks lined up, hook up the injection and fuel lines, set the idle and timing, you're done. Good Luck, TomC

[wg4t50]

No doubt, the old Detroit engines require a special type mechanic, for me, I had a love affair with them, but realized you better LOVE the engine if you wanted it to be correct, the normal Cat, Cummins mechanic had best keep his fingers out of it or they frequently would over speed and become junk. Its all under the valve covers and buffer screw.  Otherwise they were a great engine.
Today I have the Cummins ISM500 computer engine, will not go back to the DDC for a few reasons after being so spoiled, this thing has the 500 hp & 1550 Ft lb torque, and best is after my last 4700 mile run, then a 1200 mile run, the oil levl has not changed enough to see a change.  Also capable of better mpg, today average 8.5-9.0 the 12V-71 5.9, the 8V-71 6.9 then with the overdrive RTO910 and 8V-92 7.5 mpg.
Had a lot of fun with empty trucks with the 12V.  Today pass cars on mountains, yes I enjoy plenty hp on tap and run down mountains slower than I go up them.

[Eagle Andy]

Tom C hit the Nail on the on the head, mine runs great. I just don't no enough to trust it. I do all my own wrenching and can do anything on our Eagle and i have tryed to teach myself with Cliffords help from a distance, and one can say then WHY did you buy it Well I like the bus my wife like the Bus. and no we don't have alot of money falling out of our pockets  Now my wife is telling me to run it until it breaks and deal with it when that happens there is only 38,000 miles on a undoctumented motor, you all know how that goes lol.

[lostagain]

While modern 4 stroke engines are nice, ( I have several of them in other vehicles), I loved the 4-71 in the Courier 96, and I love the 6V92 in the 5C. To me it is the nostalgia of an era gone by when I used to drive and buses had 2 stroke DDs. I have taught myself how to take care of them. (Still learning...) It is a big part of the hobby for me that I enjoy. Nothing beats the satisfaction of driving the bus after rebuilding or tuning it up, feeling for smoothness and power, looking back for smoke (or lack of) under power, backing it into the shop again to take the valve covers off for tweaking... Going back to the manual and phoning Don Fairchild to understand some intricate detail of setting up the governor just right...

Once it is tuned up properly, it will go to Alaska and back several times with nothing but fuel and oil. And it won't break down anymore than any 4 stroke.

JC

 

[Seayfam]

That's what the new owner thought that bought my MC-6.
He had a mechanic go through it and then tried to drive it from Alaska down to Arizona. About 1/4 of the way into the trip, the liner seals started leaking and filled the pan with antifreeze. He didn't catch it in time and completely destroyed the engine. He got it towed back to Homer and I tried talking him into swapping in a 3406B being as he was going to have the engine out anyways, but his mechanic talked him into just going with a new silver 92 because it was a quick change. Anyways, it will be back on the trip next week, hopefully without any problems.

Sent from my GT-I9300