1986 F-250 XLT 6.9 idi C6 switch to 300 4 speed

[nic55kel]

Finally got started on this project. The truck is in remarkable condition for this area with very little rust.

I am switching out the 6.9 because it doesn't like the cold and I no longer like the noise and smoke and stink.

Project vehicle a couple of years ago - still looks the same. A patch of rust on the roof.

Just don't find trucks in this condition around here

The undercoating is still in good condition

Just about ready to pull the motor

The donor truck is a 1982 extended cab with a 300 and 4 speed, not quite sure which one.

The truck has less than 100,000 miles on it, owned by one family from new and was driven by mature drivers, but it has sat for a couple of years.

I agreed to buy the truck about a month ago but still waiting for the seller to pull his camper off of it!!!

I have not heard it run yet but I am optimistic as I judged the seller to be very honest.

A few decisions to make.

Not sure if I want to go to the expense and trouble of putting the Gear Vendors behind the 4 speed, but it sure would be nice.

I think I will stick with the diesel rad as it is fairly new and all aluminum. It would definitely require a winter front in the cold.

I hope the donor truck has a working tach in it as the diesel tach has about 50 pulses per rev vs 3 for the gas, although may be possible to modify the electronics on it - good arduino project?

Research makes me think that this will be a much easier conversion that going to the 4.9 with the E4OD.

One nice thing about taking apart the old diesel, every thing is covered in an oily film and the fasteners were surprisingly easy to remove.

As far as I can tell the diesel fuel system should be compatible with gasoline, anyone know for sure?

Thanks in advance for any help or suggestions.

Bob - North of North Dakota

 

[StraightSix]

Bob,

That looks like a blast to me. Ive been daydreaming about doing the exact same thing.

There is a guy over on full size bronco that converted a bullnose with a 302 and an e40d to a 300 with a zf5 and a hydraulic clutch. His username is "abandonedbronco". He takes good pictures and does good work, it might be woth reading over if you want to see a really clean auto - to - manual conversion.

As for the GVOD - just my two cents. In my bronco, Ive got 3.55s, a slightly moddified 300, and an np435 (1-1 top gear), all on roughly stock diameter tires. When I bought the thing I was convinced I would need to do something for OD. Ive gotten less and less concerned about it as time goes on. Im at 2000 rpm to make 50 and 2600 for 65. It breathes well a little past 3200ish,but I dont do that much. It makes its best torque around 1500-2000 and the power feels good from 2000-2500ish. So, if you're taking votes, my vote would be to skip the gvod assuming you have 3.55s or 3.73s unless you really want to routinely go faster than 60-65. Mine will happily cruise at 75 on the interstate, I just think its a bad idea for a variety of reasons.

[nic55kel]

Bob,

That looks like a blast to me. Ive been daydreaming about doing the exact same thing.

There is a guy over on full size bronco that converted a bullnose with a 302 and an e40d to a 300 with a zf5 and a hydraulic clutch. His username is "abandonedbronco". He takes good pictures and does good work, it might be woth reading over if you want to see a really clean auto - to - manual conversion.

As for the GVOD - just my two cents. In my bronco, Ive got 3.55s, a slightly moddified 300, and an np435 (1-1 top gear), all on roughly stock diameter tires. When I bought the thing I was convinced I would need to do something for OD. Ive gotten less and less concerned about it as time goes on. Im at 2000 rpm to make 50 and 2600 for 65. It breathes well a little past 3200ish,but I dont do that much. It makes its best torque around 1500-2000 and the power feels good from 2000-2500ish. So, if you're taking votes, my vote would be to skip the gvod assuming you have 3.55s or 3.73s unless you really want to routinely go faster than 60-65. Mine will happily cruise at 75 on the interstate, I just think its a bad idea for a variety of reasons.

StraightSix, thanks for the encouragement.

Thanks for the heads up on abandonedbronco I took a brief look and there is a lot of good info to work through.

I appreciate your thoughts on the OD. The truck has a 3.55 axle and I am quite happy to cruise at 65. I am a great believer in KISS and also not convinced as to how great the fuel saving would be. I know the fuel economy would increase but I don't believe the GV claims of 20%. It is still going to take as much power to overcome rolling and air resistance so the only saving is on engine friction and then there is the additional loss of the GV OD which although small is still a loss.

You have pretty much convinced me to put it together without the GV and see how it feels. If I really want an OD best to wait until I can locate a ZF5.

 

[StraightSix]

StraightSix, thanks for the encouragement.

Thanks for the heads up on abandonedbronco I took a brief look and there is a lot of good info to work through.

I appreciate your thoughts on the OD. The truck has a 3.55 axle and I am quite happy to cruise at 65. I am a great believer in KISS and also not convinced as to how great the fuel saving would be. I know the fuel economy would increase but I don't believe the GV claims of 20%. It is still going to take as much power to overcome rolling and air resistance so the only saving is on engine friction and then there is the additional loss of the GV OD which although small is still a loss.

You have pretty much convinced me to put it together without the GV and see how it feels. If I really want an OD best to wait until I can locate a ZF5.

Awesome! Im glad I could help.

If Im not mistaken, your 82 probably has a non hydraulic clutch. if so, do you plan to keep it, or convert to hydraulic?

are you interested at all in any engine performance upgrades? if so, there will never be an easier time to swap to EFI exhaust manifolds since you are already going to have to install new exhaust anyways. the only catch is that if you install EFI exhaust manifolds you will either need to go to an aftermarket intake or you will need to make some changes with your factory intake (provide heat source to intake, egr, etc).

if you decide to go with upgrades to your fuel/air induction system, Id be thrilled to send you a parts sheet for the stuff I used. it wouldn't be all inclusive, but I wrote down the part numbers for everything that wasnt trivial to figure out.

John

[nic55kel]

Awesome! Im glad I could help.

If Im not mistaken, your 82 probably has a non hydraulic clutch. if so, do you plan to keep it, or convert to hydraulic?

are you interested at all in any engine performance upgrades? if so, there will never be an easier time to swap to EFI exhaust manifolds since you are already going to have to install new exhaust anyways. the only catch is that if you install EFI exhaust manifolds you will either need to go to an aftermarket intake or you will need to make some changes with your factory intake (provide heat source to intake, egr, etc).

if you decide to go with upgrades to your fuel/air induction system, Id be thrilled to send you a parts sheet for the stuff I used. it wouldn't be all inclusive, but I wrote down the part numbers for everything that wasnt trivial to figure out.

John

Hi John, Yes I am sure that the 82 has the mechanical clutch linkage. I will see what kind of condition it is in before I make a decision on that. I don't have the parts to convert to hydraulic so that will encourage me to stick with the mechanical one.

As for the performance upgrades. I do have a 96 EFI 4.9 parts truck and also an unused walker Y pipe so exhaust manifolds for sure.

I don't think that there is an EGR on that engine. I had an 86 F150 with a carbed 4.9 and it had no EGR and no cat converter. Some sort of exemption here in Canada if over a GVWR threshold in those years.

I haven't heard the 300 run yet so once I get some compression and oil pressure readings I will decide how deep into it I want to go. It would be nice to put an Offy intake and a mild cam in it. Will have to wait and see how well the engine runs.

Thanks for the offer on the part numbers, if you have it easily available I would be very interested but don't go out of your way as I am not sure if I will do more than the exhaust manifolds.

Rainy today and so no progress. Hope to pull the old 6.9 on the weekend and also get the transmission out. Snow in the forecast after that so that will put me on hold for a few days as this is an outdoor project. Hopefully by then the donor truck will be here.

Bob

[FuzzFace2]

Hi John, Yes I am sure that the 82 has the mechanical clutch linkage. I will see what kind of condition it is in before I make a decision on that. I don't have the parts to convert to hydraulic so that will encourage me to stick with the mechanical one.

As for the performance upgrades. I do have a 96 EFI 4.9 parts truck and also an unused walker Y pipe so exhaust manifolds for sure.

I don't think that there is an EGR on that engine. I had an 86 F150 with a carbed 4.9 and it had no EGR and no cat converter. Some sort of exemption here in Canada if over a GVWR threshold in those years.

I haven't heard the 300 run yet so once I get some compression and oil pressure readings I will decide how deep into it I want to go. It would be nice to put an Offy intake and a mild cam in it. Will have to wait and see how well the engine runs.

Thanks for the offer on the part numbers, if you have it easily available I would be very interested but don't go out of your way as I am not sure if I will do more than the exhaust manifolds.

Rainy today and so no progress. Hope to pull the old 6.9 on the weekend and also get the transmission out. Snow in the forecast after that so that will put me on hold for a few days as this is an outdoor project. Hopefully by then the donor truck will be here.

Bob

You can also find abandonedbronco information over Ford Truck Enthusiasts in the motor performance area for the six motors.

I run a 300 / NP435 and Advance Adaptor's over drive in my 81 Flare side and a 2.75 rear gear.

Thing is the speed limit here is 70 MPH and if not doing that or more you will get run over!

I can tell you I am turning 1800 in OD @ 70 MPH and that is the same RPM @ 55 MPH in 1:1

Non-OD @ 70 MPH is 2500.

At 75 MPH 2700 RPM non-od / 2000 RPM in od

At 80 MPH 3000 RPM non-od / 2200 RPM in od

I can also tell you my MPG did not change between not using OD and using OD but the lower RPM is less wear on the motor. All my shifting is done below 2000 RM.

I am running EFI exh manifolds into a Walker Ypipe and stock exh system / tail pipe out past the rear tire, no cat.

I do have a heat plate on the factory intake, factory YF carb and air filter assy.

I love the little 300 motor as it pulls good at low RPM and loads of room to work on it.

Dave ----

[nic55kel]

You can also find abandonedbronco information over Ford Truck Enthusiasts in the motor performance area for the six motors.

I run a 300 / NP435 and Advance Adaptor's over drive in my 81 Flare side and a 2.75 rear gear.

Thing is the speed limit here is 70 MPH and if not doing that or more you will get run over!

I can tell you I am turning 1800 in OD @ 70 MPH and that is the same RPM @ 55 MPH in 1:1

Non-OD @ 70 MPH is 2500.

At 75 MPH 2700 RPM non-od / 2000 RPM in od

At 80 MPH 3000 RPM non-od / 2200 RPM in od

I can also tell you my MPG did not change between not using OD and using OD but the lower RPM is less wear on the motor. All my shifting is done below 2000 RM.

I am running EFI exh manifolds into a Walker Ypipe and stock exh system / tail pipe out past the rear tire, no cat.

I do have a heat plate on the factory intake, factory YF carb and air filter assy.

I love the little 300 motor as it pulls good at low RPM and loads of room to work on it.

Dave ----

Hi Dave, thanks very much for the info regarding OD gas mileage that confirms what I was thinking. Nice to save wear on the motor and I am sure it is more pleasant in the cab with the lower engine RPM. The intended use for this truck will not have me screaming down the highway at more than 70 mph so not seeing a huge amount of value added as far as the OD.

I have looked for a dyno graph that gives lbs fuel per hp/hr for the 300 but only found one for a jeep inline six but the curve looked fairly flat up to about 2800rpm so thanks again for confirming that.

I am wondering how much difference do the EFI manifolds make with the YF carburetor and with the coolant heat under the carb how much of a driveability difference during engine warm up.

I too love the low rpm torque of the 300. I put many miles on an 86 F150 with NP 435 and 3.08 rwd and a lot of that was highway miles and an OD would have been nice but it really wasn't an issue. What I really like is the simplicity and low maintenance of the drivetrain, it is pretty much a road going farm tractor.

Bob

[ArdWrknTrk]

You can also find abandonedbronco information over Ford Truck Enthusiasts in the motor performance area for the six motors.

I run a 300 / NP435 and Advance Adaptor's over drive in my 81 Flare side and a 2.75 rear gear.

Thing is the speed limit here is 70 MPH and if not doing that or more you will get run over!

I can tell you I am turning 1800 in OD @ 70 MPH and that is the same RPM @ 55 MPH in 1:1

Non-OD @ 70 MPH is 2500.

At 75 MPH 2700 RPM non-od / 2000 RPM in od

At 80 MPH 3000 RPM non-od / 2200 RPM in od

I can also tell you my MPG did not change between not using OD and using OD but the lower RPM is less wear on the motor. All my shifting is done below 2000 RM.

I am running EFI exh manifolds into a Walker Ypipe and stock exh system / tail pipe out past the rear tire, no cat.

I do have a heat plate on the factory intake, factory YF carb and air filter assy.

I love the little 300 motor as it pulls good at low RPM and loads of room to work on it.

Dave ----

Abandonedbronco is a member here.

You can tag him in your reply to notify him of this thread. 💡

[FuzzFace2]

Hi Dave, thanks very much for the info regarding OD gas mileage that confirms what I was thinking. Nice to save wear on the motor and I am sure it is more pleasant in the cab with the lower engine RPM. The intended use for this truck will not have me screaming down the highway at more than 70 mph so not seeing a huge amount of value added as far as the OD.

I have looked for a dyno graph that gives lbs fuel per hp/hr for the 300 but only found one for a jeep inline six but the curve looked fairly flat up to about 2800rpm so thanks again for confirming that.

I am wondering how much difference do the EFI manifolds make with the YF carburetor and with the coolant heat under the carb how much of a driveability difference during engine warm up.

I too love the low rpm torque of the 300. I put many miles on an 86 F150 with NP 435 and 3.08 rwd and a lot of that was highway miles and an OD would have been nice but it really wasn't an issue. What I really like is the simplicity and low maintenance of the drivetrain, it is pretty much a road going farm tractor.

Bob

It is 37 miles each way to work and all but 4 are on the high way of 65 to 70 MPH.

I dontknow how much ther EFI manifolds add as I never drove the truck with out them or the intake heater. I knew I would be driving the truck when it was cold and why I did the coolant heater when rebuilding the truck.

I like that "it is pretty much a road going farm tractor."

Abandonedbronco is a member here.

You can tag him in your reply to notify him of this thread. 💡

I did not know he was a member on here also.

Dave ----

 

[ArdWrknTrk]

Hi Dave, thanks very much for the info regarding OD gas mileage that confirms what I was thinking. Nice to save wear on the motor and I am sure it is more pleasant in the cab with the lower engine RPM. The intended use for this truck will not have me screaming down the highway at more than 70 mph so not seeing a huge amount of value added as far as the OD.

I have looked for a dyno graph that gives lbs fuel per hp/hr for the 300 but only found one for a jeep inline six but the curve looked fairly flat up to about 2800rpm so thanks again for confirming that.

I am wondering how much difference do the EFI manifolds make with the YF carburetor and with the coolant heat under the carb how much of a driveability difference during engine warm up.

I too love the low rpm torque of the 300. I put many miles on an 86 F150 with NP 435 and 3.08 rwd and a lot of that was highway miles and an OD would have been nice but it really wasn't an issue. What I really like is the simplicity and low maintenance of the drivetrain, it is pretty much a road going farm tractor.

Bob

It is 37 miles each way to work and all but 4 are on the high way of 65 to 70 MPH.

I dontknow how much ther EFI manifolds add as I never drove the truck with out them or the intake heater. I knew I would be driving the truck when it was cold and why I did the coolant heater when rebuilding the truck.

I like that "it is pretty much a road going farm tractor."

Abandonedbronco is a member here.

You can tag him in your reply to notify him of this thread. 💡

I did not know he was a member on here also.

Dave ----

If you click [assignment] right above the post button you can scroll all the members of the forum.

I saw that username the other day when I tagged Ron (Reamer) about diamond plate rail and gate caps for a Flareside.