LD-465-1C and FDC Question

[Reaper651]

Hey All,
Had enough of trying to search for it. I'm getting a 1971 M35A2 with the LD-465-1C(non turbo) engine. There are a lot of threads on here about how to disable/bypass the FDC and if its worth doing. I have also read that it helps with mileage and gives you a bit more power. Problem is, most of these threads are all geared towards turbo charged 465's. My questions are, on a NON turbo charged Ld-465, does the FDC ever have problems, is it a good idea to bypass it but set it so it wouldn't be that hard to hook back up and is it true that you will get a little better mileage and a little more power if its bypassed especially with a non turbo engine? I figure if you give it more fuel, its goin to need more air. I was thinking to bypass it because I will only run Diesel through it and it makes no sense to me to run it through the FDC but I definitely want to be able to hook it back up if I had to.

Also, is it possible to put a turbo on a regular LD-465-1C, or has the turbo charged version been changed to handle the increased manifold pressure? Is it worth doing?

Thanks in advance.

 

[ATPTac]

I don't know why you couldn't/shouldn't bypass the FDC on a non-turbo truck (maybe someone with more experience on non-turbo's can correct me if I'm wrong). The advantage of bypassing it is if it starts to leak you can contaminate your oil with fuel. Adding a turbo is as simple as getting a turbo and the corresponding exhaust components. These turbo's run 7-12psi on average depending on if your fuel is turned up. You'll see a little more power out of a turbo truck, not a ton, more noticeably you'll have reduced smoke out of the stack.

 

[Merc1973]

FYI, Mine has a LD-465-1c as well, but upon rebuild in 1989 a D-turbo was added.

 

[wb1895]

My deuce was a non turbo when I got it. The FDC should be bypassed as it is identical to all of the turbo trucks, this will save you troubles down the long road. As far as adding a turbo, buy the turbo, exhaust kit, oil lines and bolt it on. That is exactly what I did with mine, and I could not be happier. If I were you add the turbo, and bypass the FDC.

 

[Reaper651]

Thanks for the advice everyone. Fuel in the oil!?! Yeah I think I'm going to bypass the FDC for sure. I wonder is there any mechanical action going on inside the FDC to wear out? I was just thinking if its bypassed it won't be doing anything so it wouldn't wear out I would think. I need to check out the TM's on this, for that matter I need to just print them all out so I can read them without my eyes trying to focus on the d^mn computer screen. Lol lots of paper and ink cartridges but would be worth it.
As far as the turbo goes, eventually I might install a turbo, or take this engine out, find a military rebuilt LDT-465-1D in that awesome crate they come in, install it and put my LD in the crate for safe storage and have a spare motor. I think the 1D motors are higher horsepower than the 1C's, I wonder what they did and I wonder if they are reliable or less because of the power increase? I remember back(which wasn't that long ago) when it was not un-common to see deuces and 5 tons running around the job site as water trucks, And it seems that people always used to bad mouth the reliability of the multifuel. I wonder if the FDC was the main issue? The little bit of research I have done on the multi fuel has shown me that they are built a lot like an industrial engine; oil jets for the piston/cylinders, removable piston liners, and 2, three cylinder heads instead of one long one that all the companies for some reason have gone to(A BIG MISTAKE IMHO). The only thing that it doesn't have is a spacer plate which would be nice, but it doesn't seem to make a difference.
Thanks again for the advice.

 

[welldigger]

All the fdc does is retard the governor when a more viscous fuel is run through it. I highly recommend bypassing the fdc. More trouble than its worth.

I also recommend adding a pyrometer when you do bypass your fdc. This is because without the fdc doing anything it defaults to max fuel and you may need to back the fuel delivery down a bit. This is where the pyro comes in handy. You can watch your egt's before and after the bypass procedure and see if anything needs to be adjusted.

 

[ATPTac]

No problem man, good luck with your truck.

I wouldn't say the FDC causes the engine to be problematic (unless you start dumping fuel into the oil). Most of the time its due to lack of maintenance, and understanding that these aren't typical diesel engines. If you're thinking about swapping out the engine, I'd try to source a LDS, you'll get more power.

 

[Reaper651]

I will definitely look into the LDS motor, and look into getting a turbo put on the current engine. Right now my objective is to get the truck paid for and to my house. This deal couldn't have come at a worst time but its kinda a once in a lifetime deal for me, so I'm going for it. The new motor is something for the distant future, but I do want to eventually have a bunch of spare parts for this truck. As far as installing a Pyrometer, it sounds like this would be a good thing even on a non turbo engine? Very interesting about how the FDC works. I was also wondering, Can and should I remove the FDC from the Injection pump altogether? Or just bypass it and leave it on? I imagine, the I.P. would need some kind of new back plate if the FDC is removed. It also sounds like I can still run other fuels besides diesel with the FDC removed, but I must be careful with the throttle. I'm going to drive it a little bit before bypassing the FDC and I will put a pyro on my parts list. Oh I can't wait to get this truck!!! Thanks again everyone for all the help.

 

[ATPTac]

Yes, a pyrometer is a good thing regardless, especially if you're going to be bypassing the FDC and if you ever plan to tweak around with the fuel. And yes you can still run alternative fuels with the FDC bypassed, all it does is set the flow of fuel. What makes these engines multifuel is the injector and piston design, the FDC just adjusts the fuel curve for difference viscosity fuels.

Believe me your parts list is going to get very long pretty quick, it sounds like you're a lot like me and like having spares to just about everything on the truck... It's not a bad thing, it just makes an already somewhat expensive hobby even more expensive .

 

[welldigger]

Leave the fdc in place. Just bypass it. Assuming of course the truck has one. Not every injector pump has one.

 

[gimpyrobb]

I agree with most of what has been said here. I don't know that swapping out a good motor for an LDS is worth the effort. You can get an LD or LDT to similar output power as an LDS by having your injectors in top shape and adding a turbo to your system. As long as you have a pyro on the exhaust, you can fine tune the truck to have good power.

 

[brianp454]

FDC Bypass

I have a couple FDC Bypass videos on YouTube. If you look for them you will find them. My screen name is brianp454. Bypassing the FDC is highly recommended and doesn't take much effort.

I also have a new D turbo if you're interested.

Good luck with your truck!

 

[ATPTac]

I agree with most of what has been said here. I don't know that swapping out a good motor for an LDS is worth the effort. You can get an LD or LDT to similar output power as an LDS by having your injectors in top shape and adding a turbo to your system. As long as you have a pyro on the exhaust, you can fine tune the truck to have good power.

Well, he was saying he might want a spare engine. If I had the funds and space for it, and was going to get a spare engine, I'd probably opt for an LDS if I could find one in good shape. But then again, I haven't gotten around to tuning my truck in to see what kind of power I can get out of my LDT.

 

[Reaper651]

Thanks all. I was wondering about the LDS-465 versus a LD-465-1c with turbo installed. Is there a difference between the two aside from different fuel output? Can you make a turbo charged LD-465 run like a LDS-465 without sacrificing reliability?

 

[gimpyrobb]

Yes.

 

[18operator]

Hey there brianp454,
I did watch your you tube vid 1st start up. The fuel line you used, what is the manufacturer and where did you find it?
I'm looking to do the same thing with mine. Did you put a pyrometer on too?

 

[Floridianson]

18operator try and call you local NAPA and see if they still carrie the synflex line and DOT fittings. If you have a local truck parts /service center close to you they should carrie what you need.

 

[jbayer]

I just bought some Synflex (yesterday)at my local Napa for the same thing.

Did notice that inside diameter of the 3/8" Synflex is slightly smaller than the original.
Original single wall Nylon tube I.D. is .270". The original inner sleeve O.D. is .270", and the I.D. is .240".

New 3/8" Synflex tube (which is reinforced double wall, inside being nylon) has I.D of .250". The new matching inner sleeves have an O.D. of .250", and I.D of .225".
What this means is using the new is Synflex there is .015" less diameter for fuel flow.(At the ends of the tubing, through the sleeves)
Roughly 4% less.

I don't know if this amount will matter. I'm still going to put it on since my original tube will not reach the Hydraulic Head.

Oh one more thing. The original Ferrules are not symmetrical. They only get installed one way. Shorter/ flatter on the nut side.
The new ones are like standard plumbing Ferrules, symmetrical, can install either way.
I can't find the original type, so I'm reusing the old ones.

 

[peashooter]

Oh one more thing. The original Ferrules are not symmetrical. They only get installed one way. Shorter/ flatter on the nut side.
The new ones are like standard plumbing Ferrules, symmetrical, can install either way.
I can't find the original type, so I'm reusing the old ones.

You can get the original type fittings from Mcmaster.com they are on page 178 + 179 of their online catalog under "HIGH PRESSURE QUICK ASSEMBLY COMPRESSION FITTINGS"
A couple links to some common ones on our trucks are:
http://www.mcmaster.com/#50815K164
http://www.mcmaster.com/#50815K104
http://www.mcmaster.com/#50815K168
http://www.mcmaster.com/#50815K106

 

[Floridianson]

Here is a good discription of what a FDC does from TM troubleshooting the 465. After the FDC is by passed it does not defalt to full fuel it goes to the highest setting the main fuel adjustment is set at. Nothing being the same after bypassing the FDC you will need to check boost. Depending on where your main fuel is set you might need to go down as said or up to tweek. It is allways recomened to put on a Pyro if you want the most out of tweeking. If you want to keep close to the way the military had them then 12lb of boost has showen to be safe. With a pyro and boost gage we can take them higher and the Pyro will tell you when to take your foot off the throttel or down shift. If your truck runs real hot then just back down the main fuel till you get in your comfort zone.( 1200* or below) on hard pulls. I have played with the main fuel adjustment and taken it to full fuel. That is bottoming out the inner nut on the main fuel adjustment and decreased the smoke cam angle. I would never tell anyone to do what I did and I did not leave these setting that way. I also have more trucks and motors than common sence but a Deuce can be a different animal with real full fuel. If you looking to watch you fuel waist then after you get your main fuel set to where you want it you will need to back off the droop screw if your pump has one. Read the TM troubleshooting the 465 and it will walk you through everything from fuel to checking boost with useing the brakes to produce drag to creat boost.