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r686st

vmac to mechanical conversion

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Hi Everyone it's Kyle again and I haven't posted much in awhile.... I have a 1992 Mack Superliner (RW613) with a E7-350. It has the vmac computer/speed sensor and I want to convert it to mechanical. Can anyone tell me the parts needed and the part numbers? I know I will need a pedal, linkage and probably a new injection pump. Will the manual pedal out of an R model work? The more info and sooner you can tell me something the better because my driver is pulling his hair out because the truck is so slow.

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Any thing that is causing it to be slow can be repair and there is nothing wrong with the Vmac.But you can chance it by replacing the fuel pump and injector lines.If i was going to do this i would call manders 952 4691899.Talk to them and tell you are looking for a 350 HP chance over and he can tell you and should have what you want in used parts. I am running one now myself.

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My Mack dealer does not do any work on pre-2000 year model Macks. So that is out of the question... I have been told that this sure does liven the truck up. My other local mechanics don't want to have anything to do with it either. I have been told that it could be out of time so that may have something to do with it. However, no one has the literature needed to brush up on the vmac system.

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does the driver hate the performance in lower gears? or is it just in high gear? if you unplug the speed sensor does the truck perform ok? if not does the engine reach full rpm (free revving )? does the truck have proper manifold pressure under load ?

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It seems the truck is a slug in the low gears but the last two gears it pulls well. The truck has a 9 speed eatonFuller transmission, 4.17 gears and a new air-to-air under the hood. Where should I unplug the speed sensor? How do you recommend checking the manifold pressure?(boost gaugeIMG_0129.JPG.20ea08af71115078b0a604b7345082ee.JPG is a good indication???)

Edited by r686st
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23 hours ago, theakerstwo said:

Any thing that is causing it to be slow can be repair and there is nothing wrong with the Vmac.But you can chance it by replacing the fuel pump and injector lines.If i was going to do this i would call manders 952 4691899.Talk to them and tell you are looking for a 350 HP chance over and he can tell you and should have what you want in used parts. I am running one now myself.

I agree call Manders but the phone number is 800-469-1800 ask for Bill

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I think you better just sell it to me. 

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I will sell it but you won't like the price:) LOL

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Um...a Mack garage that doesn't work on anything older than 2000??? Sounds like you best find a new Mack garage, that's the most ridiculous thing I've heard.

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State Line Mack in Fitzwilliam, NH was doing tires on an AC (their AC) the other day. Not uncommon to see a B model their for work... 

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At my local mack dealer( Capitol Mack in Baton Rouge) you are lucky to see an RD!!!

Edited by r686st

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9 hours ago, cstaples said:

State Line Mack in Fitzwilliam, NH was doing tires on an AC (their AC) the other day. Not uncommon to see a B model their for work... 

They are the best!! 

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I spoke with Mander's diesel and no help on the mechanical parts. The parts guy said I could add "stage 2" injectors and that should help.  I think I am going to have the overhead run and timing checked. After that I am hoping ya'll can give any suggestions on what to do?

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Did the vmac I's have torque limiters? Just an thought. Fuel pressure must be good if pulling good at higher speeds. Boost loss due to exhaust leaks could cause that scenario. Connect airline to intake manifold and run through window with 60psi gauge. Can also try unhooking 1 sensor at a time and running it in its default until you have a change. Boost sensor, engine position, engine timing, speedometer. Does it smoke? Are egts high? Try skipping a gear to see if it pulls better.

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The truck doesn't smoke to amount to anything just a light haze of smoke when accelerating from a stop. The egts were extremely high(1200 degrees if you were to keep your foot in it) for the first few months I ran it until the water pump went out. I changed the water pump and thermostat and they stay in a safe range of no more than 900 on the hardest pull. What does a pump and thermostat have to do with egts???? I know the gauge tells the story though. 

Edited by r686st

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Nothing!  You got boost leaks or a lazy turbo in my opinion  Have the charge air system checked for leaks and if you find nothing replace the turbo! also depending where the truck is from some trucks were built with a cold weather charge air bypass for quicker warm up if it has this make sure it aint stuck in by pass mode!

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I have a 1995 ch with the electronic 350 and a 9 speed and I think it is great.  Purchased it when it was about 5 years old.  First thing we did was pull the injectors and pump.  The injectors were wore and this really spruced it up. The engine now has 22000 hours and 1,400,000 km.

I added a turbo boost gauge as well and maximum pressure for it is about 26 lbs in the cold weather.

I have 2 other ch's with 427's and one with a 454.

We drag raced the 350 and the 427 each hauling tandem loads of grain in the field and they stay side by side until you get to the last couple gears so I see no reason why it should feel doggy.

Also I've never seen my pyro over 900 degrees ever on the 350

Hoping this helps you a bit

Glen

Edited by Glensts

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