Duct from R/T Hood to Carb? Does someone sell one?

[Glennster]

After playing with the ABS Plastic and getting kind of a working prototype, I felt like I had a decent working rig.
So I did it up with aluminum, the finished product looks pretty good considering it was built by a stinking Salesman!



 I'd like to get cool air ducted to my carb......
In another post I asked about cutting a hole in my old flat hood, BUT, it would be sweet if there was a kit that would allow me to use my current R/T hood to direct fresh air to the old carb.........................
I've been Googling, but found nothing.

[MEK-Dangerfield]

I'm not familiar with your setup. Do you have a spacer under your carb, or a return fuel line to the tank? These solve most vapor lock problems.

[HP2]

No one makes one of these. The R/T scoops simply aren't tall enough to be effective in creating a decent ram air effect.

[Glennster]

MEK-D,
  I do not have a spacer under the carb, there is only a gasket between the Quick Fuel 750 and the Eddy RPM Air-Gap Intake.
  I have a Holley Blue Electric Gas Pump.
  I don't understand the return gas line to the tank, please explain. How do I plumb that? How does it help?

[jimynick]

I'd put a thick insulator gasket under that carb and see if it doesn't help. There are carb spacers made of phenolic plastic, aluminum and even plywood. The return gas line thing involves a regulator plumbed for it and bypasses any fuel that exceeds the engines demand at the rated psi. You'd have to plumb in a return line back to the tank. Personally, too much of a PITA, but it's done regularly. Good luck. 

[72cudamaan]

I'd put a thick insulator gasket under that carb and see if it doesn't help. There are carb spacers made of phenolic plastic, aluminum and even plywood. The return gas line thing involves a regulator plumbed for it and bypasses any fuel that exceeds the engines demand at the rated psi. You'd have to plumb in a return line back to the tank. Personally, too much of a PITA, but it's done regularly. Good luck. 

My understanding of a return line is a fuel vapor separator plumbed inline near the front of the engine. A small diameter (1/4 or 5/16 )
line is routed back to the tank. Never heard of a regulator. But I am interested in this set up, so any more info
may help a multitude of people here.

[MEK-Dangerfield]

Never heard of a regulator. But I am interested in this set up, so any more info
may help a multitude of people here.

This set up is slightly different than the vapor separator thing that was stock. I'll use my car as an example, but maybe all 70's were this way. There is just one line with no return. When you install the fuel pressure regulator, it will have 2 outputs. One runs to the carb. The other is to the return line. This keeps a constant flow of cool gasoline from the tank being sent up front. This way is probably the best way to prevent vapor lock, but I would try a carb spacer first. It's amazing how much cooler the fuel bowls are when you isolate the carb from the hot intake manifold. I have a 1/2" spacer, and that works like a charm.

[MTS-Challenger]

I found this on the web sometime ago (one of my future projects) - hope this helps 

------------------------------
R/T Hood Modifications
Living in Southern California does have it's advantages when you have a convertible.  On the down side 100 degree plus days and a 500 with air tends keep the engine compartment really hot!  So I decided I would try to bring in some fresh air to the carb with a few hood modifications.

I opened up the two scoops on the hood:
 
Then I took sheet metal and closed off the bottom (Engine side) of the hood and cut a hole above the air cleaner.  Put a 1/2 inch spacer between carb and manifold and used a K&N air cleaner with a top flow air plate.  This raised the air cleaner into the cavity created with the sheet metal to pull in some fresh air!

Finished it off with hood insulation to make it appear a little more "stock" looking.

Not sure how much it really helps, but you sure can hear the carb sucking in the air at an idle, once the RPM's go up all you hear are the flowmasters!

[Glennster]

I love it.......
I'm going to try to fabricate something like that too.
But first, I'll install a Phenolic carb spacer, I have room for 1'', sooooo...... 1'' it will be.
THANKS to all for your input!!!

[shadango]

I love it.......
I'm going to try to fabricate something like that too.
But first, I'll install a Phenolic carb spacer, I have room for 1'', sooooo...... 1'' it will be.
THANKS to all for your input!!!

That is what I had in mind for my scoop plans too.

What are your symptoms as far as vapor lock?   I have always had an issue where after running a while, if I shut her down and let it sit for more than 5-10 minutes, and if I try starting before it has been more than 45 minutes or so, she takes longer to crank.....and she will run a little rough at first when she starts.   

I have tried the edelbrock phenolic spacer to no avail.....I just installed a Cool Carb plate that I picked up at Carlisle.,  She still takes a bit of cranking though its seems like she runs less rough....not sure yet.  I touched the carb after running a while and its still hot to my touch in my opinion.

I dont have enough hood clearance (yet)  to try the wood spacer that edelbrock recommended........

After reading some of the posts here, I realzied that I have a 72 and it had a vapor line from the tank...wondering if I can use that for a return from my regulator??

[Glennster]

shadango,
  I don't know if I have vapor lock or something else going on.....
The problem I am about to describe has kind on come and gone over the last year. But it seems to be heat related. When it gets into the 90's with LOTS of humidity, that's when it happens.

 Some times it happens in first gear (3 speed automatic), but last time it was in second gear. Once I get up to 4,500 or 5,00 RPM's it falls on it's face.
 I went to a Holley Blue Electric Gas Pump and regulator, I though that would cure it. It also re-routed my gas line, it was only 2'' - 3'' from the headers. It gets CRAZY hot under the hood on these hot days. I wonder if feeding the motor all this terribly hot air is part of my problem.
  I'm going to use a piece of white plastic to replicate what mttchall did under his hood. I will try to heat the plastic so the hole in it will drop down to the bottom of the air cleaner, then I try to seal it so it pull air through the scoop on the R/T Hood....

[MTS-Challenger]

Glennstar,

I wish I could take credit for the hood scoop mod but as mentioned "this is something I found on the web".

One other additional modification to the design I will make is to increase the air cleaner base (base only) diameter from the standard 16" K&N size to a 22-24" diameter (see what fits). Then add dense foam around the outer edge of the cleaner base to create a sealing ring to seal up against the inside hood panel when the hood is shut closed. This should make for a cool ram air effect using the dual scoops on top of the bulge hood.

In fact thinking about it, a few carfully located drilled holes between the airfilter and foam sealing ring would flow some of that cool ram air to the carb outer body. Or a trap door with a cable control would be even be better to control the cooling/ram air pressure.

Benefits
1. Ram air
2. Cold air to intake
3. Hood insulator pad utilized

Enjoy!

[HP2]

Pumping cooler outside air through the carb is usually done to increase horsepower, not to cool the carb, althought it does help some. If you have vapor lock issues, first i'd try an electric pusher pump. The stock puller will struggle with high heat situations. 2nd, I'd add a small heat spacer to isolate the carb. Even a .25" wood composite can help. 3rd, add a cool can or fuel cooler immediatly before sending fuel to the carb. Finally, insulate or move fuel lines so they are away from direct heat sources.

The plastic hood liner to isolate the incoming air is a neat idea, but, some plastic has a "grain" so to speak and heat will cause it to warp one direction. Also as it heats up, it expands and can push its way into places you don't want it to be. Be careful with this effort as it would really stink to have your plastic ram air plenum bend down and touch a hot component and catch fire.

Again, I'll say that the factory dual scoop design are not the greatest for ram air benefit because they are so low. Shakers have the same problem. That is why in a full out effort, the factory came up with the taller six pak, T/A, and AAR designs.

[shadango]

Pumping cooler outside air through the carb is usually done to increase horsepower, not to cool the carb, althought it does help some. If you have vapor lock issues, first i'd try an electric pusher pump. The stock puller will struggle with high heat situations. 2nd, I'd add a small heat spacer to isolate the carb. Even a .25" wood composite can help. 3rd, add a cool can or fuel cooler immediatly before sending fuel to the carb. Finally, insulate or move fuel lines so they are away from direct heat sources.

The plastic hood liner to isolate the incoming air is a neat idea, but, some plastic has a "grain" so to speak and heat will cause it to warp one direction. Also as it heats up, it expands and can push its way into places you don't want it to be. Be careful with this effort as it would really stink to have your plastic ram air plenum bend down and touch a hot component and catch fire.

Again, I'll say that the factory dual scoop design are not the greatest for ram air benefit because they are so low. Shakers have the same problem. That is why in a full out effort, the factory came up with the taller six pak, T/A, and AAR designs.

What do you recommend for insulating fuel lines?

[MEK-Dangerfield]

What do you recommend for insulating fuel lines?

I've seen a fuel line heat shield sleeve. I believe Summit Racing carries it. It's shiny aluminum looking, so I don't know if I would go that way just for aesthetic reasons.