Engine Markings????

[Speddmon]

Hey all,

First off I did search. Maybe I wasn't using the correct search parameters, but I did look.

I have a question about the multi in my deuce. I never really cared much about it until I was looking at a post by another member trying to re-time his hydraulic head. cranetruck posted a few images from the TM about the timing marks and procedure and I noticed that the timing mark used for the LDT and the LD are different, and that's when I figured I better find out just what I have.

I know the most of the deuces have the LDT in them. I also know that the LD's were originally non turbo engines, but that some of them may have been converted over.

The engine tag in my truck is badly worn and you cannot make out anything on the tag except for the fact that it is a Herculese engine...you can barely even see that it is a multifuel on the tag. Are there any markings on the engine that would let me know what engine this is for sure, before I run into a situation when it will matter and I don't know what I've got?

It is a TD block and was rebuild in 1994. From what I've read the TD was a later change made to the engines so i'm thinking I don't have an LD that was converted to turbo. But how can I tell what it is for sure? Is there another casting in the block I can look for or something? I can almost rule out the LDS as well, since it doesn't have enough power to be the LDS.

By process of elimination I could assume that it is the LDT, but we all know what happens when you "assume"...I want to be positive of what it is.

Thanks in advance

 

[uscgmatt]

My tag looks just like yours, if you get up close with a rag and wd-40 you should be able to read the stamped info. Which on mine was LDT-465-1D and at the bottom right 89. Hope this helps.

 

[drgreg]

If it is a TD block I would bet my left one it is a LDT.

 

[oldshep]

ldt

 

[doghead]

Simply put, LDT stands for Liquid cooled, Diesel, Turbo.

So, if you have a turbo on your engine( I can tell in your picture, you do), that makes it an LDT, no matter what it was when first built or installed in the truck. (unless it is an LDS)

The important thing to know, would be, is your IP timed to the LDT mark(if you have a turbo, or is it still timed to the LD mark, if it was built without a turbo originally.


btw, LDS stands for, liquid cooled, diesel, supercharged! It is not really supercharged(just a turbo), it was only called this, to distinguish it from the LDT 130 hp engines.

 

[Speddmon]

DH, or maybe some of the other experts.

Would a converted LD (now and LDT) still timed as an LD at the hyd. head cause a pretty good loss of power? Cause this thing seems like a dog to me, even slight grades on the highway affect it....it will pull them in 5 high, but it's floored and the RPM's drop down to about 2200 or so. Once it's down to 2200 RPM's it seems happier, and just chugs up the grade, but the one I drove back from PA for Mahdey had way more power than mine does.

Edit; By the way, I am going to buy a pyro and turn up the fuel some when I get back to working and get some cash. But I'm wondering if I wouldn't be better served to verify the timing of the IP before I do any of that???

 

[gimpyrobb]

If it is a TD block I would bet my left one it is a LDT.

Well, uh, I just brought a motor home from the GA rally and it is a non-turbo LD motor with the TD stamp on it. Guess we should call you "righty" from now on?

 

[gimpyrobb]

Tom, from what I was told by Stretch, the timing being off makes the motor louder, not weak in the way of power. Get the pyro first. Also and ld motor that has a turbo added is now an ldt. So, if yours has a turbo, you need not worry if it is/was an LD. There are also markings on the IP that state what motor it is for. That could help you find out more info too, since the motor's passenger side tag is in such poor shape. Call with any questions.

 

[elkhunter]

I have a 1972 AM General and a Hercules LDT- 465 - 1D and the tag is dated Oct 1987. Its a turbo and quiet.

 

[wsucougarx]

I have a 1972 AM General and a Hercules LDT- 465 - 1D and the tag is dated Oct 1987. Its a turbo and quiet.

Quiet?

 

[elkhunter]

Non- whistler!

 

[Speddmon]

Tom, from what I was told by Stretch, the timing being off makes the motor louder, not weak in the way of power. Get the pyro first. Also and ld motor that has a turbo added is now an ldt. So, if yours has a turbo, you need not worry if it is/was an LD. There are also markings on the IP that state what motor it is for. That could help you find out more info too, since the motor's passenger side tag is in such poor shape. Call with any questions.

Thanks Gimp,

That helps to clarify some things. I do have a few more questions though. You said the IP's are marked for what motor they go with, I have to assume that an IP that was originally meant to be on an LD motor can still be re-timed and made to run just fine with an LDT?

Also, I was reading a little (actually I just started dabbling into it) on turning up the fuel. Unless I read the post wrong, I thought it said that if your FDC is bypassed and the fuel wasn't turned up, it can cause the truck to have less power. Is this true, anybody know? My FDC was internally bypassed by the military, and they even went to the trouble of scribing a nice little note on the brass plate bolted to the top of the FDC to let me know this...LOL. What I do not know is if they ever turned up the fuel? If they didn't could this be a good reason for my lack-luster power performance??? Or does the FDC being bypassed have absolutely nothing to do with it???

 

[Jake0147]

The very short version of the FDC is that it "turns down" the fuel rate for fuels with a higher energy content. Bypassing it makes it "sense" lighter fuels, thus a maximum fuel rate. It is based on viscosity, which is what it actually measures... Bypassing it gets the maximum fuel rate, since no highly viscous fluid (which among the authorized fuels means "high energy fuel) will be sensed.
The FDC is bypassed externally... An "internal bypass" wouldn't be a bypass at all. It would sound more to me like somebody "wedged" the compensator (by adjustments or otherwise) to keep the fuel rate at the compensater's maximum compensation.

 

[Speddmon]

Some interesting developments since last posting on the subject.

I talked to some members about the FDC, and read up on bypassing the FDC a little.

Turns out my FDC, even though it is marked "Internally Bypassed" was also bypasses the correct way (Externally). Since I never looked into the subject before, I didn't really know what to look for, but when you're looking for it, it stands out like a sore thumb...see picture.

Now, back to the lack of power issue. When the FDC is bypassed, you need to turn the fuel down some at first. Since this was done by the military and they do not use pyro's...is it safe to assume that they just turned the fuel down a certain amount to be on the safe side?? If that is the case, then it's also safe to assume that my lack of power could be caused by that same issue, of them turning down the fuel rate without anything to measure the EGT's to tell them how much was too much.

My next step is going to be getting a pyro and turning it up and playing with it some to see where I like it best.

 

[rlwm211]

DH, or maybe some of the other experts.

Would a converted LD (now and LDT) still timed as an LD at the hyd. head cause a pretty good loss of power? Cause this thing seems like a dog to me, even slight grades on the highway affect it....it will pull them in 5 high, but it's floored and the RPM's drop down to about 2200 or so. Once it's down to 2200 RPM's it seems happier, and just chugs up the grade, but the one I drove back from PA for Mahdey had way more power than mine does.

Edit; By the way, I am going to buy a pyro and turn up the fuel some when I get back to working and get some cash. But I'm wondering if I wouldn't be better served to verify the timing of the IP before I do any of that???

The Multifuel is not a powerhouse by any stretch of the imagination. If you are pulling hills in 5th, and staying over 2200 you are getting about the best the engine can offer. It is only 140 hp and very low torque as compared to many diesels today. I am not sure where the top of the torque curve is but I would bet that you found yours at 2200.

The design of these engines is for endurance and efficiency. Driven properly your truck and engine will last far longer than any civilian vehicle you can find. The fact that you make speed is indicative that the engine is doing what it can. Run it any harder and you will only shorten the life of the engine.

2200 is considered by many here, myself included, to be the desirable cruising RPM and to run any faster simply wears the engine out and risks throwing various internal parts all over the outside of the engine. Do a search on deuce engine failures and you will find a host of strings about how these engines will self destruct if they are abused and sometimes for no obvious reason.

I care for my truck enough to want to do what is right to keep it in as good of shape as possible including driving the truck as per the manual. You can turn up the fuel and do all sorts of things, but understand you are tampering with a pretty well designed machine.

Just my two cents

RL

 

[Speddmon]

The Multifuel is not a powerhouse by any stretch of the imagination. If you are pulling hills in 5th, and staying over 2200 you are getting about the best the engine can offer. It is only 140 hp and very low torque as compared to many diesels today. I am not sure where the top of the torque curve is but I would bet that you found yours at 2200.

the issue I'm having though , is that I'm not pulling hills, I'm driving up what I consider SLIGHT grades on the highway, not hills. The truck drops from 2400-2500 down to 2200 to get up the hill. I've driven other trucks (stock) that had way more power than mine does. I drove one home straight off the base for another member, and the hills we were pulling in PA were much more of a grade than I'm driving around here, and his truck pulled them fine, 2400 rpm's with pedal left over....mine is floored to get to 2400-2500 on flat ground.

 

[rlwm211]

I apologize for missing that portion of the trhead you posted. I would check the fuel filters and also the air filter to make sure those are in proper working order. Any reduction in fuel supply will be felt in top rpm operation. Also an air filter can look clean and still be quite filthy. The air filter is washable. There is an article in the references section regarding that procedure.
Once you have verified that all else is well, proceed with your efforts to increase power by adjusting the pump.

Best of luck

RL