Hello all.., I want to begin with a few admissions first: I drive a "bullnose" Ford product because:

(1) I prefer a carb vehicle, and this series was the last Ford Truck committed to carbs (with the exception of the EECIV 302))

(2) It offered the option of a 4.9L (300-6) motor that has become my engine of choice. (making locating factory spare parts ..wiring, transmissions, cross-members etc very easy.)

(3) I can stand to look at it..(the body style, lines etc.)

(4) Most of the wiring, which IMHO is the life of the rig is basically still very simple, and in most cases still in pretty decent condition when found original, if not can be reproduced by hand very easily.

That being said, I have found a need to address an issue that plagues most all carb'ed vehicles, some more than others when considering the different ambient air conditions we all face where we live in the world.

CARB HEAT..and the need thereof.at different times and special occasions. (especially when temps are near freezing with moisture or humidity in the air)

I own 2 "bullnose" Broncos, at this time. I have chosen to run a small bonnet carb air cleaner to utilize engine compartment air for the most part at this time. The way it was done for many years before. You may wonder why.

Briefly, I need to admit that as a holder of private pilots license, I still equate the need for carb heat with a CABLE, along with CABIN heat..again cable operated.

I GET carb ice..and the neat for heat but I have decided to opt for a manual cable solution for when I REALLY need heat NOW, than wait for the "temp" sensor to decide what what my needs are.

I know this is a long post and thank you for your patience. I realize that a cable solution to carb heat may not appeal to some and that's ok, I just feel I want to investigate what options exist for me iof I want to adjust the little flapper door own my own.

I seem to remember a Ford air inlet tube that utilized such a manually actuated door valve but may my memory is playing tricks on me..sometimes it does..anyway..

I still have my manifold stove, and may in the future find a manual cable arrangement feeding the OEM bonnet. but in the mean time, I'll let the little free-air bonnet suck up all of the obnoxious fumes from my old smelly engine compartment like it did for many years before all of the more modern venting solutions...(and as a bonus, I can adjust the carb while running with the air cleaner attached without special tools)

If I can find that (or fabricate) that manually operated flapper door to the warm air /cold air duct, I'll have a cable in the cab with the label "CARB HEAT". (I can't imagine a modern carb arrangement being anything else for a real world daily drive in all climates, but especially for those who operate in sub-zero weather).

 

Sounds good to me. g But then, I have an aircraft throttle cable (temporarily) shifting the C6 in my '81 F150.

 

Most all these trucks originally had the air cleaner with the snorkel and the hose going down to the heat stove around the exhaust.

If you are a manual type of guy, do you trust a air switch to control the vacuum like this?



Find an original air cleaner in the junkyard, install it, and run some lines into the cab to the above switch. One from the intake manifold(vacuum source) and one out to the valve. Flip the switch and it activates the flapper door in the snorkel. Flip it back and it opens it up.

Make sure you install the switch correctly if you get one, you need to exhaust the line to the actuator when you flip the switch to off.

This would work, but it would not work as well as the original setup. It had a temperature control inside the aircleaner housing, and it actually modulates the flapper door more or less, keeping the temp as even as possible.

 

we have another ""earth-free" enthusiast think'n outside the box..it'll never be the same..maybe we'll all begin to think "vernier"?..

 

Sounds intriguing but, I think I'd prefer to take ALL of the guesswork outa' the loop, and be able to activate that warm air on partially or fully as I see fit..MANUALLY.

Good idea though... a mix of old school and new..yet not total control. Once you've done it, it's addicting to actually hear and feel it when the carb ice is melted and the engine runs smooth again..as you head to final approach.. re-assuring actually..in those situations, you want carb heat and you want it NOW..it's a distant memory but a real one.

 

Another user 'Dorsai' recently repaired the exhaust plenum on his I-6.
This is the one that directs heat to the floor of the intake manifold under the carb.

Not sure that he made a thread of his own, but you can look back through his posts to find it.

 

Here you go.

https://www.ford-trucks.com/forums/1...bout-this.html

 

Good reading hear of course. I actually have the original stoves for both of my current Broncos, (351w, & 300W-6). However on my 300-6 86' I have the EFI exhaust manifolds which didn't come with a stove. I use a water heated Clifford on it and for the most part it does a great job, even when temps are in the 20's, although slightly sluggish till water temp is up (to be expected). On the 86 with a Clifford and large horn carb installed, there isn't room for a factory bonnet because of the a/c housing being in the way anyway.

I have wondered about fabbing a stove for the EFI manifolds but haven't really been pushed to solve a problem that really hasn't been unmanageable yet..yet.

The 351HO is another story. The original heat-riser/intake vacuum thing isn't operable, and w/o exhaust heat or water u'neath the carb, it's pretty cold shouldered, till absolutely warmed up. IT definitely could use carb heat when air conditions are right or WRONG for good running when COLD. So far I've been muddling thru , and have chosen to not repair or purchase what would fix the heat stove for it..Hence my theoretical quest for a manual/cable flapper door solution.

If I can get this done on my 351W, it should be too hard to do the same after fabbing some kind of stove for one of the EFI manifolds on my 300-6.

Thanks for the input everyone..running a carb efficiently in cold conditions..a challenge for certain some days.

 

While I understand your penchant for keeping it simple, a little "smarts" working for you can go a long way. A carb knows basically nothing about temperatures, and yet temperatures make a big difference in the quantity of oxygen in a cubic measure. So to give the right air/fuel mix a carb needs air fed to it at a constant temp. How are you going to do that? You can't, without a lot of effort in a gauge to read the temp and a lot of attention from you in changing the flapper as the temp changes.

So why not just connect up the temp sender in the air cleaner to the flapper in the snorkel, fix the heat stove, and take advantage of all the "smarts" that are sitting there? It will automagically keep a constant air inlet temp to the carb, at least until summer hits. And then it'll give far cooler air to the carb than your open air cleaner, which is pulling in HOT air from the engine compartment.

Why do you want to throw all of that away when it is easily connected and virtually bullet-proof?

 

Sorry, I didn't realize from your first post that you had EFI manifolds
I looked at where you said -paraphrasing- I have a bricknose (bullnose really, bricknose are the '87-'91 trucks like mine.) and that you wanted a manual cable to apply carb heat.

I'd be tempted to run exhaust through the water passages.
There are plenty of 'Lake Pipe' style cable operated cutouts.
They could be plumbed into the Y-pipe instead of the cast iron manifolds.

 

I was wondering the same thing, Gary.

JohnSmith, you are SERIOUSLY over-thinking this whole thing and trying to reinvent the wheel. Ford already did what you are trying to accomplish and kept it simple and all under the hood; it's called a thermostatic air cleaner.

 

I understand carburetor icing in air cooled aero planes.

Descending from altitude 1000's of feet with the throttle closed can really put a chill on an air cooled motor. There really isn't any way to regulate temperature except to put some heat into the carb.

However, I've never really heard about carburetor icing in cars. Maybe it's because they're water cooled and the water temp is regulated by the thermostat. That and with a car or truck you never really get to coast like you do in a plane.

If it was me, and all the parts are right there, I'd restore it to original operation first, and then decide if I want to "fix" it.

 

All very good arguments, Gary for using what is there for sure. After writing all of this out and representing my thoughts on paper, I want to say, I am a believer in cooler outside charge air mostly as an up-to-temp operating mode in general with adding warmer air potentially for warm up or severely cooler operating conditions. Exactly how much the average therm o-temp plenum system actually does add at what ambient air temp is probably something to be schooled on, with maybe even different part numbers used for sensors based on location, CFM rating on carb used etc. It would be interesting to know.

I have decided to focus on what my 300-6 "needs" if anything to make it the best it can be given it's equipment at this point. My 351wHO equipped 85 has a few more issues to be addressed, intake, carb etc, and is generally a fair weather "sport" vehicle anyway for the most part at this point. I actually am working on a 300 for it as well and that brings me to the real question. How to build this next 300 for colder weather.

Now that I've built a great running 300-6 with a custom Clifford Intake and carb I like, along with the EFI manifolds that are popular, what should I do to maximize IT'S balanced approach to "fresh outside air generally" with added "warm air" when or IF needed. It doesn't have any "stove" on the exhaust..YET. I will also have to find a custom air cleaner with a sensor for the size needed. (room).

In 1980, I took my E250 SUPERVAN (300-6) To Alaska for a 4 year adventure. We visited inner Alaska quite a lot thru two winters with temperatures well below 30 below and lower plus wind chill. With a stock intake, and exhaust system and a little HEET, carefully we stayed running. Of course some days it wasn't wise to be out. I have been In the roughest parts of Alaska in other vehicles a lot colder than that but of course they were more prepared it.

 

I'm sorry I mis-represented "bricknose"..I just changed that thank you.

Good suggestions about the "y" pipe option..I've begun to get some ideas about where or which manifold to use for a fabbed-up stove..thanks

 

I've noticed some of these stats listed by a few vendors, I wonder if they could be broken down by part number as to their "closing" temp?..assuming they are defaulted "open" when cold.
Thanks for the input.