Finally bypassed the FDC in my deuce.

[ageregunner]

Last week I bypassed the FDC in my 1971 M35A2. Today I finally got to take it out on a test run to see if the differences described in several Steel Soldiers posts, would apply to my truck. The difference in hill pulling was simply unbelievable. Hills that made me downshift all the way down to third gear, could now be pulled in fifth. My EGT display now has become a vital part of this truck, as I now can easily hit the 1200 degree F limit. But that being said, the improvement to the performance of this truck is amazing. Thanks for all the posts on bypassing the FDC. The procedures shown were easy to follow. I highly recommend all deuce owners to install EGT gauges on their trucks, and then bypass their fuel density compensators.

 

[rustystud]

Last week I bypassed the FDC in my 1971 M35A2. Today I finally got to take it out on a test run to see if the differences described in several Steel Soldiers posts, would apply to my truck. The difference in hill pulling was simply unbelievable. Hills that made me downshift all the way down to third gear, could now be pulled in fifth. My EGT display now has become a vital part of this truck, as I now can easily hit the 1200 degree F limit. But that being said, the improvement to the performance of this truck is amazing. Thanks for all the posts on bypassing the FDC. The procedures shown were easy to follow. I highly recommend all deuce owners to install EGT gauges on their trucks, and then bypass their fuel density compensators.

Just be careful as now you have the ability to fry your pistons ! Just because you have a "Pyrometer" installed doesn't mean it cannot happen either. In just a moment pulling hard you can reach the critical temperature that will destroy your engine. I once had a Semi-Truck reach 1400 F in minutes pulling up I-5 . I just glanced down to the gauge and realized what was happening and let off the fuel in time. They do make Pyrometer alarms that you can buy.

 

[gimpyrobb]

Well, at least with the pyro, he has an educated idea of whats going on inside.


Just cause a truck is stock, that doesn't mean it won't fry something, especially if lugging the motor!

 

[cattlerepairman]

I have a pre-turbo thermocouple in my LDS. FDC is bypassed and I am still wary of the power it has. No way would I turn it up more, even though it seems to hardly get up to danger temps, ever. That thing pulls like a freight train. The key is to drive it right; downshift and keep the rpm up, do not torture it at low revs with the pedal mashed to the floor. Lugging sees the temps climb fast and even then, lifting the pedal just a tiny bit produces a noticeable drop in pre-turbo temps.

 

[ageregunner]

Just be careful as now you have the ability to fry your pistons ! Just because you have a "Pyrometer" installed doesn't mean it cannot happen either. In just a moment pulling hard you can reach the critical temperature that will destroy your engine. I once had a Semi-Truck reach 1400 F in minutes pulling up I-5 . I just glanced down to the gauge and realized what was happening and let off the fuel in time. They do make Pyrometer alarms that you can buy.

Thanks for the response, Rusty. My electronic EGT unit has an alarm, which I have set for 1100 degrees F. It lights a bright alarm light on the display, but after reading your reply, I will probably use the alarm contacts to energize a loud audible.

 

[FloridaAKM]

I bypassed the FDC in the '85 Deuce yesterday, but have not had a chance to drive it due to the missing HH parts that were broken. Floridianson suggested it since all of the injector lines were removed & it was just a matter of removing some fittings & lines &plugging them & lengthening the output of the secondary filter to the HH. If it works as well as you guys mentioned, I will probably do it to the '87 Deuce as well. I do have the necessary EGT gauges to help mind the temps while driving. Thanks for your reports.

 

[frank8003]

Last week I bypassed the FDC in my 1971 M35A2.~ My EGT display now has become a vital part of this truck, as I now can easily hit the 1200 degree F limit. But that being said, the improvement to the performance of this truck is amazing. ~ I highly recommend all deuce owners to install EGT gauges on their trucks, and then bypass their fuel density compensators.

The FDC was stuck, [failed] as described by rustystud in copious notes.

 

[Floridianson]

I have a pre-turbo thermocouple in my LDS. FDC is bypassed and I am still wary of the power it has. No way would I turn it up more, even though it seems to hardly get up to danger temps, ever. That thing pulls like a freight train. The key is to drive it right; downshift and keep the rpm up, do not torture it at low revs with the pedal mashed to the floor. Lugging sees the temps climb fast and even then, lifting the pedal just a tiny bit produces a noticeable drop in pre-turbo temps.

Agreed if you lugging it will get hot fast.
This is my GMC 3500 when I go to pass someone for just maybe 30 seconds.

 

[cattlerepairman]

Thanks for the response, Rusty. My electronic EGT unit has an alarm, which I have set for 1100 degrees F. It lights a bright alarm light on the display, but after reading your reply, I will probably use the alarm contacts to energize a loud audible.

I think you are very much on the safe side. The consensus from many threads seems to be that you do not want to see more than 1250-1300 pre-turbo, so you do have a little wiggle room.

 

[MudMarine]

Two questions,

1. (On topic) where's the best place to get said EGT gauges from? I've seen some of the surplus aftermarket dealers here advertise their kits but those don't look like they come with any kind of alarm

2. (Off topic)
I keep forgetting to ask and haven't found a smoking gun thread, but the LDS motor is the one that give more power and RPM right? Part 2, what trucks came with LDS, 5-tons?

Sorry for hijacking the thread a little!

 

[Fatalid]

The digital aftermarket gauges have a programmable alarm light and relay, so you can hook that up to the buzzer or something along those lines...

http://www.auberins.com/index.php?main_page=product_info&cPath=5_21&products_id=147

 

[gimpyrobb]

Two questions,

1. (On topic) where's the best place to get said EGT gauges from? I've seen some of the surplus aftermarket dealers here advertise their kits but those don't look like they come with any kind of alarm
I have used Stewart Warner and Hewitt on my trucks, been happy with both.
2. (Off topic)
I keep forgetting to ask and haven't found a smoking gun thread, but the LDS motor is the one that give more power and RPM right? Part 2, what trucks came with LDS, 5-tons?
Yes mostly 5tons, some deuces were surplused with them but only a tiny amount

color added

 

[MudMarine]

Thank you both! Hopefully I can make a deal on a 5 Ton motor I found near me then!

 

[gimpyrobb]

Honestly, if you tune you LDT, it will have similar power to an LDS. I certainly wouldn't go through the effort of a motor swap for the little gain gain you'd get.

 

[cattlerepairman]

Here is a good thread for a late night read: https://www.steelsoldiers.com/showthread.php?56041-LDS-VS-LDT-and-the-real-differences

Basically, if you have a late model LDT, swap in the rocker assembly from an LDS and tune, as gimpyrobb said, for LDS power.

 

[ageregunner]

The digital aftermarket gauges have a programmable alarm light and relay, so you can hook that up to the buzzer or something along those lines...

http://www.auberins.com/index.php?main_page=product_info&cPath=5_21&products_id=147

This is what I have in my deuce. Just ordered a Sonalert to wire into the alarm relay contacts.

 

[MudMarine]

Here is a good thread for a late night read: https://www.steelsoldiers.com/showthread.php?56041-LDS-VS-LDT-and-the-real-differences

Basically, if you have a late model LDT, swap in the rocker assembly from an LDS and tune, as gimpyrobb said, for LDS power.

You weren't kidding about this being a long thread! I'm about 30 pages deep so far

 

[rustystud]

You weren't kidding about this being a long thread! I'm about 30 pages deep so far

You can always just go to the last ten pages and read the final results. Though that is kind of a spoiler.
Hey MudMarine, where you in the Marines ? Since you mention Mud does that mean you where a "ground pounder" ? I was in Tanks ie:1811 Tanker. Fun times had by all !

 

[MudMarine]

You can always just go to the last ten pages and read the final results. Though that is kind of a spoiler.
Hey MudMarine, where you in the Marines ? Since you mention Mud does that mean you where a "ground pounder" ? I was in Tanks ie:1811 Tanker. Fun times had by all !

I am currently in the Marines as a Maintenance officer. I used to use this handle back in highschool on the Pirate 4x4 boards so I figured I'd recycle it here.

 

[rustystud]

I am currently in the Marines as a Maintenance officer. I used to use this handle back in highschool on the Pirate 4x4 boards so I figured I'd recycle it here.

An NCO or actual OFFICER . I was a E-4 in Tanks then later transferred into Motor Transport.