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

[StraightSix]

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.

"Word on the street" about the intake manifold heat plate is that its fairly important, especially up where you are. My bronco is pretty cold natured after removing the stock exhaust heat to the stock intake manifold. Once it warms up its great, but even in the mild ga winter (30f mornings are pretty typical) it needs a minute to warm up and get its feet under it.

Ive heard that there can be issues with fuel condensing inside of the intake manifold at really low ambient temps. Ive never seen anything to support that rigorously. What people alledge could happen is liquid fuel running down the manifold toward #6 and lean burn towards #1. Im not sure I beleive all of that, but it does need warm up time for sure.

I would also think that the water plate could be providing some cooling in hot weather which is more common down here. I had occasion to measure temps in my engine bay with an IR gun a while back and the intake stayed at about 185f consitently after warm up, despite the truck idling for well over an hour and the intake sitting right over the exhaust.

[StraightSix]

"Word on the street" about the intake manifold heat plate is that its fairly important, especially up where you are. My bronco is pretty cold natured after removing the stock exhaust heat to the stock intake manifold. Once it warms up its great, but even in the mild ga winter (30f mornings are pretty typical) it needs a minute to warm up and get its feet under it.

Ive heard that there can be issues with fuel condensing inside of the intake manifold at really low ambient temps. Ive never seen anything to support that rigorously. What people alledge could happen is liquid fuel running down the manifold toward #6 and lean burn towards #1. Im not sure I beleive all of that, but it does need warm up time for sure.

I would also think that the water plate could be providing some cooling in hot weather which is more common down here. I had occasion to measure temps in my engine bay with an IR gun a while back and the intake stayed at about 185f consitently after warm up, despite the truck idling for well over an hour and the intake sitting right over the exhaust.

I tell people that are skeptical of my 300 that the bronco is a tractor with highway gears pretty regularly.

[ArdWrknTrk]

"Word on the street" about the intake manifold heat plate is that its fairly important, especially up where you are. My bronco is pretty cold natured after removing the stock exhaust heat to the stock intake manifold. Once it warms up its great, but even in the mild ga winter (30f mornings are pretty typical) it needs a minute to warm up and get its feet under it.

Ive heard that there can be issues with fuel condensing inside of the intake manifold at really low ambient temps. Ive never seen anything to support that rigorously. What people alledge could happen is liquid fuel running down the manifold toward #6 and lean burn towards #1. Im not sure I beleive all of that, but it does need warm up time for sure.

I would also think that the water plate could be providing some cooling in hot weather which is more common down here. I had occasion to measure temps in my engine bay with an IR gun a while back and the intake stayed at about 185f consitently after warm up, despite the truck idling for well over an hour and the intake sitting right over the exhaust.

Any time you combine a venturi and the latent heat of phase change from a liquid to a vapor things get cold.

These are the laws of thermodynamics and have nothing to do with bias or superstition.

Your sweat evaporates.

It cools you off.

If you wipe yourself down with alcohol it feels even cooler, because alcohol evaporates more readily that saline.

Hold an air tool that uses constant flow on a hot day. (something like a die grinder or DA sander)

That tool is going to get cold.

Pressure drop is responsible.

The same way Bernoulli's principal draws fuel out of a carburetor's jets and boosters.

We have air moving from a higher pressure to a lower pressure. (except this time it is ambient pressure to that of manifold vacuum)

In extreme cases this will lead to humidity actually freezing -carb icing- and this is one of the reasons Ford uses a CWM in the stock air cleaner that should provide a near constant 105°F.

 

[nic55kel]

Any time you combine a venturi and the latent heat of phase change from a liquid to a vapor things get cold.

These are the laws of thermodynamics and have nothing to do with bias or superstition.

Your sweat evaporates.

It cools you off.

If you wipe yourself down with alcohol it feels even cooler, because alcohol evaporates more readily that saline.

Hold an air tool that uses constant flow on a hot day. (something like a die grinder or DA sander)

That tool is going to get cold.

Pressure drop is responsible.

The same way Bernoulli's principal draws fuel out of a carburetor's jets and boosters.

We have air moving from a higher pressure to a lower pressure. (except this time it is ambient pressure to that of manifold vacuum)

In extreme cases this will lead to humidity actually freezing -carb icing- and this is one of the reasons Ford uses a CWM in the stock air cleaner that should provide a near constant 105°F.

I understand that the manifold requires heat, I have experienced carb icing, when I worked in a nickel mine North of the 55th parallel (nic55kel), and so my concern is more does the coolant heated manifold work as well as the stock configuration?

 

I am retired now and no longer have to drive in all weather conditions so not a major concern but I would expect that the warm up time is longer with the coolant as the source of that heat, just wondering if it is very noticeable.

Has anyone any experience with the coolant heated manifold at around 0 deg F?

As Jim points out maybe the CWM setup pulling air from around the exhaust manifold would be the best solution for a quicker warm up and driveability in cold weather.

Project delayed by weather as it is very wet out and we have snow in the forecast for this weekend.

Bob

 

[ArdWrknTrk]

I understand that the manifold requires heat, I have experienced carb icing, when I worked in a nickel mine North of the 55th parallel (nic55kel), and so my concern is more does the coolant heated manifold work as well as the stock configuration?

 

I am retired now and no longer have to drive in all weather conditions so not a major concern but I would expect that the warm up time is longer with the coolant as the source of that heat, just wondering if it is very noticeable.

Has anyone any experience with the coolant heated manifold at around 0 deg F?

As Jim points out maybe the CWM setup pulling air from around the exhaust manifold would be the best solution for a quicker warm up and driveability in cold weather.

Project delayed by weather as it is very wet out and we have snow in the forecast for this weekend.

Bob

It certainly doesn't get hot as fast as having the raw exhaust playing against the intake manifold plenum floor, but it does work as the coolant warms.

And I'm pretty sure that it is bypassing the thermostat.

So it should warm long before the radiator sees any flow.

[FuzzFace2]

It certainly doesn't get hot as fast as having the raw exhaust playing against the intake manifold plenum floor, but it does work as the coolant warms.

And I'm pretty sure that it is bypassing the thermostat.

So it should warm long before the radiator sees any flow.

The heating of the intake from either the stock exh manifold or coolant and the heated air through the air filter do 2 different things.

The hot air through the air filter keeps the carb from icing as it is HOT air going into the carb.

The heating of the intake keeps the air / fuel mix mixed. If you were to cool off the mixture the fuel would drop out of the air and pool on the intake floor and "spill" in to each hole.

Look at compressed air systems, when the air it hot the water stays in it, cool off the air and the water falls out of it. Same happens to the air / fuel mix.

The heated intake keeps this mixture mixed!

Now I run EFI exh manifolds with the factory intake & carb.

I also have the coolant heater for the intake.

As for the heat to the air filter there is no easy way to add the tin to the EFI to capture the heat but have the vacuum hooked up so the flapper should work.

I do have air pulling from down that area of the exh manifolds and from in front of the radiator support.

I have used my truck when in the high 20's wich only a short warm up.

I keep it in the house garage so it is a little warmer, back it out side and let it run while I grab the last few things and turn off lights.

I have only had it sputter 2 times that could have been from the carb icing but not sure?

It is a 2 mile drive from my house to the high way and only 1 light of 3 I get stopped at other wise on the high way for the next 35 miles.

Same when I leave work, fire it up, text wife on my way home and into gear and maybe under 1 miles to the high way if I go that way or then back roads at 45 MPH. I only have 1 light either way before getting on high way or 3 milea before next light andb the motor have some temp in it by that time.

When I did the EFI manifolds I knew I was going to drive it when cold and why the intake heater install.

Dave ----

[nic55kel]

The heating of the intake from either the stock exh manifold or coolant and the heated air through the air filter do 2 different things.

The hot air through the air filter keeps the carb from icing as it is HOT air going into the carb.

The heating of the intake keeps the air / fuel mix mixed. If you were to cool off the mixture the fuel would drop out of the air and pool on the intake floor and "spill" in to each hole.

Look at compressed air systems, when the air it hot the water stays in it, cool off the air and the water falls out of it. Same happens to the air / fuel mix.

The heated intake keeps this mixture mixed!

Now I run EFI exh manifolds with the factory intake & carb.

I also have the coolant heater for the intake.

As for the heat to the air filter there is no easy way to add the tin to the EFI to capture the heat but have the vacuum hooked up so the flapper should work.

I do have air pulling from down that area of the exh manifolds and from in front of the radiator support.

I have used my truck when in the high 20's wich only a short warm up.

I keep it in the house garage so it is a little warmer, back it out side and let it run while I grab the last few things and turn off lights.

I have only had it sputter 2 times that could have been from the carb icing but not sure?

It is a 2 mile drive from my house to the high way and only 1 light of 3 I get stopped at other wise on the high way for the next 35 miles.

Same when I leave work, fire it up, text wife on my way home and into gear and maybe under 1 miles to the high way if I go that way or then back roads at 45 MPH. I only have 1 light either way before getting on high way or 3 milea before next light andb the motor have some temp in it by that time.

When I did the EFI manifolds I knew I was going to drive it when cold and why the intake heater install.

Dave ----

Okay Dave, thank you for the detailed info. I will make my final decision on that when I am getting the motor ready to install. I will mainly be using the truck spring thru fall and only occasionally in winter so if it takes a little longer to warm up not a big deal. But nice to know it will run properly in the cold just in case it is needed.

I seriously doubt that the sputtering had anything to do with carb ice. When I had it happen it was on a long highway run and it took over an hour to build up. The symptoms were a very noticeable loss of power, I think the conditions of humidity and temperature have to be just right for this to occur as I only experienced it once. When I pulled over the heat of the engine melted the ice and I continued on with no more problem. As I recall it was about 10 below F with high humidity.

This truck will not be a daily driver, probably not go more than 4 - 5000 miles a year. I mainly want it as it is very cheap to insure older trucks here and my 2007 6.0 F250 is way more truck than I need and it doesn't like to sit for more than a week or two. And that 6.0 is a high maintenance engine.

Thanks to all for your inputs.

Bob

[FuzzFace2]

Okay Dave, thank you for the detailed info. I will make my final decision on that when I am getting the motor ready to install. I will mainly be using the truck spring thru fall and only occasionally in winter so if it takes a little longer to warm up not a big deal. But nice to know it will run properly in the cold just in case it is needed.

I seriously doubt that the sputtering had anything to do with carb ice. When I had it happen it was on a long highway run and it took over an hour to build up. The symptoms were a very noticeable loss of power, I think the conditions of humidity and temperature have to be just right for this to occur as I only experienced it once. When I pulled over the heat of the engine melted the ice and I continued on with no more problem. As I recall it was about 10 below F with high humidity.

This truck will not be a daily driver, probably not go more than 4 - 5000 miles a year. I mainly want it as it is very cheap to insure older trucks here and my 2007 6.0 F250 is way more truck than I need and it doesn't like to sit for more than a week or two. And that 6.0 is a high maintenance engine.

Thanks to all for your inputs.

Bob

I also had to "rig up" hot air for the choke because the EFI manifolds dont have a pass through to get heat from.

I took copper tubing and put a few wraps around 1 of the manifolds and up to the choke, that fresh air side gets hooked were it should also.

As for the stumble it only happened 2 times and it was shortly after I got it on the road for the drive to work. It does not warm up much before I start out and it was as I was pulling up to the light 1/4 mile from my drive. I guess the choke could have pulled off to soon?

Other wise it runs great.

Dave ----

[nic55kel]

I also had to "rig up" hot air for the choke because the EFI manifolds dont have a pass through to get heat from.

I took copper tubing and put a few wraps around 1 of the manifolds and up to the choke, that fresh air side gets hooked were it should also.

As for the stumble it only happened 2 times and it was shortly after I got it on the road for the drive to work. It does not warm up much before I start out and it was as I was pulling up to the light 1/4 mile from my drive. I guess the choke could have pulled off to soon?

Other wise it runs great.

Dave ----

The weather has told me I need to take a break.

The old 6.9 is ready to pull with just the last two bottom bellhousing bolts still in place.

As you can see I am definitely going to need heat on the manifold, the plate to feed coolant to the heat riser pocket looks straightforward to fabricate so will go that route.

I am still waiting to get the donor vehicle so not sure what kind of choke is on it, I am pretty sure that it is an original YF carb with no EGR and no cat converter so the distributor should have the correct advance curve.

By the end of the week the snow should be all gone and things dried up. Hopefully the donor will be ready to pick up by then and I can get back to it.

Bob

[nic55kel]

The weather has told me I need to take a break.

The old 6.9 is ready to pull with just the last two bottom bellhousing bolts still in place.

As you can see I am definitely going to need heat on the manifold, the plate to feed coolant to the heat riser pocket looks straightforward to fabricate so will go that route.

I am still waiting to get the donor vehicle so not sure what kind of choke is on it, I am pretty sure that it is an original YF carb with no EGR and no cat converter so the distributor should have the correct advance curve.

By the end of the week the snow should be all gone and things dried up. Hopefully the donor will be ready to pick up by then and I can get back to it.

Bob

Well the seller finally released the truck - had to wait for the ground to dry up some.

I will get it towed home in the next day or two - rear drivers side wheel brake is seized.

Not too surprising as it has sat for probably 4 years.

Temporary fuel tank by washer bottle.

Judging by the condition of the interior and the rolled over odo (in kilometers) the truck appears to have about 70,000 miles on it.

I got it running - started easily - runs beautifully, no blow by and oil pressure up at the m even when warm, idled nicely and good throttle response. Clutch felt really smooth and the T18 shifted smoothly and felt really solid.

Truck came with a free camper, originally was to have been removed but I think the seller ran out of time. He has sold the farm and has a lot of junk to dispose of quickly.

Not a huge bonus as the camper needs a lot of work, but very salvageable, I am sure that some one will want it.

Anyway excited to be getting the truck home and get moving on this.

Bob