Power differences in my deuces?

[blacktop]

I Really cant find any info to answer my question. I have 2 deuces, 1st is a 1969 model with C turbo,white engine, around 800 hours .The FDC Is still hooked up. My 2nd truck is a 1970 model, D turbo, herculies engine and around 300 hours. The FDC has been bypassed, it was that way when I bought it.
The 2nd truck (1970)feels like it has twice the power of the first truck. My 69 seems very doggy on hills and dosent accelerate very fast. I know these trucks are not hot rods but the 1970 model I have will pull hard going up hills( no downshifting) and flat out acccelerates almost as fast as you can shift. I am concerned that it may be set up two much. There is a small amount of black smoke under load on the faster truck. So-is my 1969 truck a dog or is my 1970 truck over fueled. They both start very well and run great. Any Ideas? Thankyou for your info.

PS these are the only deuces I have driven.

 

[cranetruck]

Difference in fuel delivery, get a pyrometer....

 

[swbradley1]

Blacktop,

My first Deuce runs like a scalded dog with his rear on fire. Pulls going uphill and has a lot of throttle left at 55mph (no, I'm not saying go faster).

My second Deuce has significantly lower performance.

1. "C" turbo with FDC
2. "D" turbo bypassed FDC

Just the opposite of yours.

Get a pyrometer.

sw

 

[cranetruck]

The fuel delivery threaded rod (Stop Plate adjustment) is a good indicator of amount of fuel made available to the IP.
With FDC in the circuit: About 0.3 inches showing
Wit FDC bypassed: About 0.2 inches showing

I'm still collecting data on this, so any new input is welcome....

 

[scrapman]

Pyrometer. Adjust your fuel under load conditions. Transmission 1st gear, transfer case low range apply brake & throttle simultaneously until you have throttle wide open and enough brake to hold engine RPM in the 1800 to 2200 range. o-1000* supersafe 1000-1150* good if watched closley 1175*+ DANGER Will Robinson!!!

 

[BKubu]

I believe Bjorn is correct. But other factors could be at play here, too. Even the deuces that have been rebuilt were mostly rebuilt 15+ years ago. Which truck was rebuilt and when? As with any motor vehicle, they were subjected to varying use, abuse and maintenance (or lack thereof). I definitely think these factors play a part in the performance of the truck. Also, you never mentioned anything about the tires...they are often overlooked. If the air pressure in the tires on one truck is low, this will impact the power. Make sure you run several tanks of clean fuel and conditioner through the trucks and change the filters a few times after you get the truck. Dropping the fuel tank to clean it out wouldn't be a bad idea either. Then, see what you've got.

My third car is a 1990 Dodge minivan. I've driven in friend's minivans that have more and less power than mine and some of them are older and newer than mine. Maintenance, condition, and use mean something.

 

[bryan70546]

what is a FDC is it good are bad

 

[cranetruck]

The FDC (Fuel Density Compensator) adjusts fuel delivery according to its viscosity so that any one or mixture of fuels specified for the engine will produce the same power output. Works for #1, #2 diesel, kerosene and gasoline. However, if biodiesel or veggie oil is used, which has higher viscosity, but less BTU/gallon, the FDC works incorrectly.
It relies on a metal to metal seal within and may leak fuel into the crankcase, so is bypassed routinely. Picture above is of the FDC.

 

[scrapman]

A large number of multifuels had the FDC bypassed by the military for emission reasons and had the fuel adjusted to run primarily on #2 diesel. There is usually better performance to be had by increasing the fuel rate into the 1000*-1100* range.

 

[bryan70546]

thanks for the info

 

[gimpyrobb]

A large number of multifuels had the FDC bypassed by the military for emission reasons and had the fuel adjusted to run primarily on #2 diesel. There is usually better performance to be had by increasing the fuel rate into the 1000*-1100* range.

Thats not quite true. The turbos were added for emissions. The FDCs have a habit of dumping fuel into the crankcase, thats why alot were bypassed. The FDC's purpose is to keep the power output at the same level, no matter what fuel is run through the motor. So, fuels with less BTUs have more fuel dumped into the cyls, fuels with the most BTUs were cut down. Bypassing the FDC is like running the motor "wide open". It seems like you get a big boost in power, when you actually are getting the most fuel delivered possible. You can burn your motor up real easily. A pyro is the best way to tell when something is going to melt.

 

[scrapman]

Yes, I will concede that the turbo was the 1st big step towards emission control by introducing more air (oxygen) for a more complete burn. The next step was FDC bypass to standardise fuel & settings to achieve more uniform results in the emissions produced. This is a example where a full and complete answer could & would cover several pages. We could even say the FDC was invented as part of the moon landing cover up. But with everyone's response alot of information can be gained and all who participate benefit.

 

[SasquatchSanta]

Pyrometer. Adjust your fuel under load conditions. Transmission 1st gear, transfer case low range apply brake & throttle simultaneously until you have throttle wide open and enough brake to hold engine RPM in the 1800 to 2200 range. o-1000* supersafe 1000-1150* good if watched closley 1175*+ DANGER Will Robinson!!!

Have you tried this?

I did a rolling "load" calibration test a year or so ago and found it next to impossible to hold the engine at a given RPM in high range on the transfer case. I can't imagine using low range.

I can't find my old post which also gave the TM I followed but if memory serves me properly the TM calls for high range, first gear and doing tests at 1600 RPM for the droop and (I think) 2000 for the main fuel setting. The TM stated a manifold (boost) pressure spec for both RPM ranges. If the boost was too low, turn up the droop of main setting and if it was too low, turn down.

Regardless of what the TM says, I won't do these tests again. I think it's too hard on the truck. You basically have to stand on the accelerator while standing on the brake pedal. The truck does NOT like it. I think it's a good way to tear something up.

 

[scrapman]

Yes, I have used this method quite often with sucess & no broken parts. I usually am able to complete the test in 50 yards or less so I'm not loading the brakes for an extended period of time. As far as driveline strain goes, it is not much different than pulling up a steep incline under a heavy load. It is a steady pull without a shock/jerk motion.

 

[SasquatchSanta]

I found the thread that covered the tests I did last year. The TM is 9-2910-226-34.

Here is a link to the page that tells about the tests: http://www.steelsoldiers.com/deuce-modification-hot-rodding/24388-ip-pump-calibration-economy-2.html

I found these tests very difficult to do.

 

[SasquatchSanta]

I see where you were reading EGTs instead of boost pressure. This may be a more universal way, possibly even better method of testing.

Also, where I may have experienced a lot more violent bucking may be in the fact that I was not only trying to hold the engine back with maximum fuel but also to slow it down 200 RPM.

It sounds like you were picking an RPM and then applying brakes and fuel to hold that RPM.
Attempting to knock a couple of hundred RPM off of the engine speed with the brakes while applying maximum fuel was not plesant. I was afraid Rosie was going to hand me a drive shaft or two

Thanks for your input

 

[scrapman]

Yeah, that is how I do it, motor up to x-rpm apply brake then as rpm begins to drop apply more throttle to maintain rpm at desired level until full throttle is achieved. Read boost & EGT let truck settle at idle, make adjustments & repeat. You can get high HP #s on a dyno if you rev the motor up 1st then pull it down with the waterbrake, but it is a false reading. Proper use of a dyno is like the procedure as outlined here. Throttle/brake/throttle/brake until you have full throttle @ x-rpm then ease off the brake taking your readings at whatever intervals you determine until you reach your max rpm or when power & torque drop significantly. And once in awhile you do use the broom & dustpan in the dyno cell, but that is racing.

 

[SasquatchSanta]

What you're doing/suggesting makes more sense than that the TM calls for. Reducing the RPMs from 2,600 to 2,400 and 1,800 to 1,600 in low gear under full throttle with the brakes is really stressful.

 

[bassetdeuce]

Yeah, that is how I do it, motor up to x-rpm apply brake then as rpm begins to drop apply more throttle to maintain rpm at desired level until full throttle is achieved. Read boost & EGT let truck settle at idle, make adjustments & repeat. You can get high HP #s on a dyno if you rev the motor up 1st then pull it down with the waterbrake, but it is a false reading. Proper use of a dyno is like the procedure as outlined here. Throttle/brake/throttle/brake until you have full throttle @ x-rpm then ease off the brake taking your readings at whatever intervals you determine until you reach your max rpm or when power & torque drop significantly. And once in awhile you do use the broom & dustpan in the dyno cell, but that is racing.

Any complaints from the neighbors?

 

[blacktop]

I installed a pyro scrapman had sent me (wow that was fast! your payment is on your way) I tryed the brake-w.o.t. test there was so much going on I only watched the pyro, it hit 1000 before I had to shut it down before going through the fence. On the road at 55 mph it runs about 850 degrees, if you stomp on it it will run up to 950. On a long fairly steep grade at 55 it will run aroun 1050 and wide open up a steeeep hill at 55 I hit 1150 degrees. I have come to the conclusion that with me driving and the type of use I do I should be safe. What do you guys think? Thankyou scrapman for sending the pyrometer.