Hello All, I have a ? about exhaust manifolds that maybe someone out there can answer. I have a 1966 F-100 2wd longbed with the 300 ci 6 cyl engine and stock 4 speed and Dana 44 posi. I am doing some work on the truck and wanted to update some while I was at it. The exhaust manifold was cracked really bad and I wanted to go with headers but didn't have the $$$ so I found a set of EFI dual 3 into 1 manifolds from a mid 80's bronco and I know that the port spacing is the same but now that I have everything off and am ready to go back together it doesn't look like the rear manifold will work, the front looks fine, has anyone done this swap before and maybe have some pointers???? Thanks in advance, Ted in South Dakota

 

When you say the rear manifold will not work, what is the problem? Clearance with the frame? Someone who has already done this can tell you for sure, but I seem to remember someone posting about having to slightly notch the frame. You may be able to find a thread that discusses this by searching the forums.

I have the same manifolds & plan to use them someday on my '61 or my '68, so I "have a dog in this hunt." You will not have exhaust heat to speed warm-ups, which could be a problem in the winter. You might need to rig something. I am thinking of some sheet metal that catches exhaust heat that you would just put on in winter. May stock Ford engines collected heat from around the exhaust manifold and routed it into the air cleaner intake to speed up warm-up.

 

I just used the Heddman headers, dual outlet, I think they were about $100. The real handy thing was wrapping them with header wrap, keeps the engine bay much cooler, and if you happen to get to close, no BURNY!

 

Hi again, on the front manifold there is an actual bolt hole on the top front so that helps with hanging that one but there isn't one for the rear and I did some more fitting and I think I can make it work and it doesn't look like there will be any problem with the frame or having to notch or anything like that. As far as the cold weather, we get some of that here in SD and I am putting on a later model carter carb with an electric choke on it for that little prob, had to have the intake manifold modified for it as it is a larger bore that the stock 1100 1 barrel carb and the bolt holes were further apart as well. I would however like to know where you got a pair of headman dual outlet headers for $100, that is a deal.. ya'll have a good one. later, Ted

 

Ted,

The electric choke operates the choke, instead of using exhaust heat to operate it. The other heat I am referring to is the heat at the base of the intake manifold, right at the bottom of the vertical port the carb bolts to. In the pre-EFI system (common to almost all carbed sixes) the exhaust manifold has a "heat riser" valve that directs the exhaust up against the bottom of the intake right below the carb. This valve opens (IF it is not stuck!) when the engine warms up. This helps evaporate raw gas during warm-up. (EFI systems must control the gas much more carefully to get along without the heat riser.)

Glad to hear you resolved your difficulty, as I thought I had read of this swap being done successfully several times on these forums. I do think you will need some intake manifold heat before next winter sets in in SD. Without it you will need a long warmup and, even then, a lot of expensive gasoline will go past your rings into your oil and out your tailpipe without ever evaporating.

 

Well, after further inspection, that was 5yrs ago,,,,, and it was $119, but it was through summit racing.

 

I'm using the EFI exhaust on my 84 F150 (79 block). To make things easier to install I installed studs on the entire bottom of the head, this made it much easier to get the manifolds lined up. For manifold heat I made a plate for the bottom of the intake (I have an offy "C", the stock intake has the same fittings on the bottom), installed 2 fittings on it & run water from the heater through. I've only had the carb ice over once (before I installed the heating system).
Edwin

 

Great idea Edwin. I had not even thought of carb icing, but I guess that can stop you. (I lived in southern CA most of my life & never even used anti-freeze until I was 30-something in UT.) (I did use a water-pump lube/anti-corrsion additive.) Did you make your own plate? Any chance of getting a sketch or more detailed description? I have a well-equipped shop and I will either use your idea or make a sheet-metal heat riser off the exhaust.

Ted, another option that will not be as pretty, but will not require much fabrication is to bend a turn of two of soft copper (or aluminum) tubing around the carb base & pack glass insulation to trap the heat around the carb. Run your heater feed through this tubing. This will not help until the engine has warmed up, but it should reduce icing.

In general, I think Ford went with exhaust heat because it comes on immediately and speeds up warm-up. Both of the above ideas do not take effect until the engine temp comes up. I would be interested how many 240/300 people with tubing headers (or EFI manifolds) have had winter drivability problems (or not).

P.S.: I think that the various systems that piped exhaust manifold heat into the air cleaner during warm-up were also part of Ford's winter drive-ability solution, as was the plate plumbed with coolant under V-8 carbs.

 

Its only happened to me a couple of times. Colorado is fairly dry, but when its cold & humid it can be a problem. The first time it happened to me the truck was barely driveable. The carb was a ball (literally) of ice.
I think that I have a picture of the plate somewhere, I'll have to look for it though. Basically its a 3 or 4" square, 1/2" or 3/4" plate of aluminum. I used the gasket that came with the manifold as a guide & drilled the correct mounting holes (3). From there I drilled & tapped 2 holes for some 90 degree water fittings. As I had the manifold off at the time so I was able to test fit everything a little easier. I don't have the exact dimensions as its currently on the vehicle & I'm currently overseas, though I suppose its not really all that important. I wouldn't get any thicker plate than 3/4" as it might interfere with the exhaust. One additional thing I did do was make a system of valves so that I can run the hot water through in the winter, but strait to the heater in the summer. I guess its probably just as well as I didn't do a very good job sealing the plate & it leaks a little. It does work though & I've had no problems with carb icing since.
Edwin

 

I think I got it. At first I thought the coolant just ran through the plate, but then I thought it would be more effective to have the plate seal the chamber and let the coolant run right against the bottom of the intake. With your leak in mind, the best thing would be to use a cast-iron or steel plate that would better match the expansion rate of the manifold and to install it while the manifold was off.

I doubt that running it all the time in series with the heater would hurt as one usually has the heater off when the weather gets hot. This is the way many Ford V-8's were set up in the '60's.