I have a carbed 355 in my 91 rs camaro. The temp runs a max. of 190 but It still causes the fuel to boil. I can watch it boil in the clear filter. The fuel pump is a holley red and when the fuel boils it kills the fuel delivery I think it is because the When the fuel boils it builds up pressure and shuts down the pump. What is the best way to route the fuel line to help keep the fuel cooler. Is there anything I can do to get more air into the engine. I have a stock hood and can not afford an aftermarket hood. Thanks.

 

You didn't say, but it sounds to me like you have headers...

How close does the fuel line come to the headers right below the evaporator housing? If it's like most of these cars, I'd bet it's less than ½" of clearance right there.

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"So many Mustangs, so little time..."
ICON Motorsports

 

Yes I have headers, but the line is about 6- 8 inches away from the headers. I ran new fuel line back to the tank so I didn't have to worry about air leaks. The fuel line runs over the valve cover across the intake and into the carb.

 

I really need help on this one. Thanks

 

I can't speak from before/after experience, but it makes sense to me to keep the fuel circulating. You do that by putting in a 3-port regulator with return line to the tank. When demand is low, fresh, cool gas will kept at the pump because the excess, which would be sitting there getting warm without the return line, is going back to the tank to that "cool" reservoir. When demand kicks in, it'll be cool fuel going to the carb which won't sit there long enough to be picking up heat.

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five7 is right, a return line will do alot towards stopping vapor lock. Imagine how slow the fuel is flowing through the lines at idle or at normal speeds. The heat soaks into it. When it vapor locks, get underneath the car and feel(carefully) all the fuel lines to find out where the hot spot or spots on the fuel line are.

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

What about fuel pressure. Wouldn't a return line lower the amount of fuel avalible to the carb.

 

That is where the regulator comes in handy. the return line hooks to the 3 port regulator five7 was talking about earlier. The regulator only allows excess fuel to return in order to maintain constant pressure to the carb. It's nice on the pump too, because it doesn't have to work so hard building pressure and moving very little fuel when you are just driving around town and at idle. The pump runs cooler because of the additional fuel flow.

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

The stock pump for one of these cars with a carb has a return line coming off of it.

The way it works, is that the pump has the capacity to pump a whole lot more fuel than the motor can actually use. The only time the pump's full capacity even might be needed is sustained max RPM WOT. The rest of the time the pump is loafing. The stock system on these cars uses a pressure valve such that when some adequate pressure is reached, any extra fuel that the pump can move is allowed to return to the tank.

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"So many Mustangs, so little time..."
ICON Motorsports

 

Exactly. The factory saw the light and did this, but I'm not sure when (both the '82 V6 and '86 V8 donor had the 3-port mechanical pump w/return line).

I assumed the Holley red is a two-port fuel pump that was used during the conversion. The car originally had a fuel return line that likely was plugged off. Am I correct?

 

Yes, that is correct. I hooked up the return line and regulated it. It helped some but after about 30- 45 min the fuel is still boiling. there is no where for the heat to go under the stock hood. The third gen camaros suck at getting fresh air into the engine and hot air out. I think I'm going to put vents in my hood. Any one have any other suggestions on how to get the hot air out of the engine compartment. Thanks

 

Are you sure the fuel is 'boiling' or is it just air bubbles from a leak in the tank. Does it happen when the tank is low and stop when you have it filled??

 

There is no air leak.

 

Check the hoses at the tank (if you have any rubber back there). The hoses can crack and let air into the system. Been there... Done that!

 

I'm with air being in the system.

 

Hey MK, you haven't by any chance recently put in a cat-back or anything have you? Do you still have all the heat sheilds in place back there? Also, have you removed the filter media and just looked at the flow thru the tube to see what it looks like?

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"Education is the art of making man ethical.

-George Hegel

 

Third gen fuel lines are on the other side of the car, so the cat isn't going to do it.

But maybe the dog would?....

 

What about at the tank. It could be to close there. Also, I would think that if the exhaust is on just a fuel line, it wouldnt take 45minutes to boil.

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We are the future, the 21st. century dislexyic, glue sniffing, cyber *****, with homicidal minds and handguns.

 

You might try about a 3' piece of heat shield sleeve on the line under the hood.

 

Which is why I said "cat-back" and referenced "back there", when most put the intermediate pipe in, they toss the flashing from the tunnel (which runs right next to the tank), and if he also removed the muffler sheilding when he installed his muffler it would be even worse.