After measuring the I.D. of my new EFI mannies, 1 11/16", I became concerned with Flow and performance with that restriction.

So, I started searching for ways to vent the heat from the headers which causes hard hot starts. I tried a heat shield between the intake and carb, diverting heat around the carb, but that did not help.

Now I'm thinking of cutting a slot in the hood to allow the hot air to escape. I don't know if I could go to such extremes, but if it solves the problem and allows me to retain performance, then it may the next step. I would also add a scoop and face to toward the cowl.

While searching around for remedies, I found these photos from guys with the same issue.

 

I have a Toyota Landcruiser with an I6, and they all got a "carb fan" under the hood,
even when they went to EFI.
It kicks on when you shut down and things are hot, and it then runs for about 20 minutes
just keeping the area around the 'carb' cool.
It's just tucked into the inner fender, and it has a nozzle that blows cool air at the carb.

Nissan did the same thing with their I6's that weren't crossflow.

I think I'd try that before cutting the hood- well, unless you have a louver tool!

hth
t

 

Thanks for the info, TobyB. I had no idea. I searched around and found this:

adding a 3" carb cooling fan w/duct for aluminum carb ? Speed Talk

I believe I'll go that route, and wrap the lines with insulation.

 

make an exit small scoop in my 86 Bronco when I can find just the right kind of "scoop". What I have in mind is a vent about 2-1/2" wx8" long cut in the passenger side of the hood (matches the bracing uneath) exiting toward the windshield. I want a "louver" about that wide that I can block with something for cold winter use but open for summers..

I haven't found the right "already-made" scoop yet. I may have to fab it...but I will do it before summer. It may be only about 1" high..and if painted, you may not see it at first. Good idea actually. and CUSTOM.

 

this is just another example of why I think the need for a heated intake manifold is way over rated. with efi exhaust manifolds the bottom of the intake is radiant heated by the close proximity of the exhaust. also why the factory used a squirrel caged blower to cool the injectors on efi models.

I ran into a similar situation when I installed a built 460 in my '46 ford pickup. that thing will run down the freeway all day with sufficient air blowing under the hood to carry off the heat. but take an exit ramp and stop at a red light and the truck stalls and is hard to restart. installation of a fuel return line from the carb to the tank helped a little but did not completely solve the problem. I regret not using intake manifold gaskets that have the heat riser passageway blocked off. I will retrofit gaskets with blocked off heat risers asap.
in cold climates I think supplying hot air to the carb is the first order of priority for good driveability - a hot intake floor would be secondary.

 

A carb fan seems like a really cool idea. I know my carb usually overheats when I need it most, which is climbing a steep mountain road on a 100* day. It'll start sputtering and stalling out, and I have to wait for everything to cool back down before I can get gas back to the tank (it's usually dry all the way back to the tank. I've checked.) I wonder if pointing a fan at the carb would help solve this. Just one that I can click on with a switch under the hood.

I know it's a tough situation for heat because generally, in these situations, the harder it's working, the slower I'm going, so the more heat I'm generating, the slower I'm driving! (2 - 5 mph in low range).

Cool idea.

I also wonder if my fuel pump fatigues from heat and stops drawing fuel. Maybe one on both sides.

I agree it's probably a little less invasive than cutting a hole in the hood, although that might look pretty cool if done right.

If you were to do the hood, I wonder if something like this would work:

 

but I assume it also has a water drain built in..if so very nice..

 

A little rain water never hurt anything.

Yeah, that'd be the tricky part. I wonder how that could be set up.

 

When I did my custom intake on my 351w I DID modify the crossover gaskets..and very glad I did for summertime use..a little cold natured when cold..but runs fine warm.. but still would benefit from those neat hood exit vents..

 

Very interesting that AB, who has efi mannies, has heat issues as well. I thought that swapping efi's for the header would put me on the yellow brick road.

The issue I have with the hood scoop, is that it is a guess. Will the hole be large enough to rectify the problem, would a fan be needed? If it doesn't help, I'm left with hole in my hood.

One of the other posters mentioned how both Toyota and Nissan use Carb fans (even on the injected models) of the I6's. It is nothing more than a fan (the 'caged squirrel type' as FTF called it) mounted on the fender that sucks cool air in the blows it at the carb.

 

Heh, well, keep in mind that the only time I really run into issues is in some pretty precarious situations. 20* incline on some old rocky mining road, revving the engine to 3000 RPMs but only moving at 3mph, 100* out, 8000 feet elevation, four people (probably a few dogs) and a full load of camping gear in the back. It's working pretty hard, and there's not an ounce of air flow. It really sucks when suddenly it starts sputtering and stalling out because the fuel's boiling.

I don't ever run into issues on a daily basis around town or the interstate.

Yeah, cutting a hole in the hood is a pretty permanent solution, unless you went and got a junk hood just to try it out.
But the fan just moving air across the carb seems like a good idea. Mounting it to the fender doesn't seem like it'd be difficult.

This one seemed like it could work:

 

Holley Cow, AB, that is quite a picture you describe. I certainly understand now.

I like that fan you found. I suppose I could make a sheet metal shroud for it that attaches to 3" dryer duct (all the formula 1 guys use it, ha ha). It is low amp draw and high cfm. I was thinking more something like this:

http://www.ebay.com/itm/3-In-Line-Blower-12V-Boat-Bilge-Galley-Heads-Engine-Ventilation-Marine-Cool-Fan-/161556590321?pt=Boat_Parts_Accessories_Gear&hash=item259d85eef1&vxp=mtr

 

There may not be a best answer that fit's everyone's situation. I am now running an open 10" air-cleaner , because mainly I hav'nt found that "early" 302 Bronco remote mount large horn air cleaner. (my bad) In the winter time I know I'd somewhat benefit from a version of Ford's "warm-air" induction as was standard on what came with my 4.9L powered 86 Bronco.

After warm-up, it runs great with a heated intake in most conditions with the ambient air I drive thru (the upper-left coast with mild temps year around)

On those two weeks or so in August, I notice with my a/c on the temps start climbing and although I have not experienced any vapor-lock issues, I notice the heat range climbing above what it usually does and with my tight new rebuilt motor, I can tell when re-starting it IS hotter.

I run a heated/cooled Clifford with a single float-bowel Auto-lite, so my results may vary from those who have different carburation.

I know about vapor-locking. I remember dual-action fuel pumps on y-block Fords of the 50's, I also have experienced vapor-locking in a 60's Corvair. I have never experienced vapor-lock in my 300-6 Bronco.

I remember the days of close-pins on fuel lines..and wrapping wet rags on fuel lines...oh the joys of motoring when it was an adventure. Actually the neat part of carburation is in general, an adventure because of not being computer controlled, and as such needs human intervention from time to time (not for everyone).

I will vent my hood for the extra air-flow to assist overall cooling, but with this water cooled Clifford, I find no need for it to operate successfully at least in the area I daily drive, the upper left coast.

If you operate your modified Ford product in other climate zones, your results may be different.

 

I always try to think of ways to test an idea before making permanent changes [i.e. hole in hood].


Try this: remove the hood when ambient temperatures get high and see if your problem disappears.


Or, try this: Make some block spacers to be placed between the hood and the hinges. This way, the rear of the hood will be higher and will allow air to be drawn out as you are traveling down the road. Years ago, local policemen routinely pulled the hood latch to release the hood of their cruisers to the safety catch position, when idling for extended periods. The hot air was allowed to escape and yet they could still answer a call without pushing the hood down.


Just some ideas!

 

a fuel return line will help more than a carb fan. the slow moving fuel in the supply line gets heated by all the underhood and exhaust system heat. ford put fuel return lines on many 460 powered luxury cars. put a .080 restriction in the fuel return line and adequate fuel pressure will be maintained.