Return fuel line on 1970 el Camino - Page 2 - Chevelle Tech
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post #16 of 24 (permalink) Old Dec 22nd, 17, 9:50 AM
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Bob
 
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Re: Return fuel line on 1970 el Camino

Some more trivia from an old guy:
What does the so called term vapor lock mean? Think about this: When you boil water it turns to steam or VAPOR, When you boil Brake Fluid it turns to VAPOR. In 1962 drag racing my C/G 38 Chevy. At the end of the 1/4 I had NO BRAKES. Kill the engine and in a few seconds I had a full pedal.
Cause: Headman Headers blowing hot exhaust on brake line.
When you boil gasoline it turns to VAPOR. A 7040205 will no operate on VAPOR, Must have liquid.
So I Call my Brother in law Bill, From Mich, He says call my friend BOB, I call Bob and answer many questions for this Bob guy. He tells me on the phone the problem with my 70 454. So I do what this Bob guy tells me to do.
After I follow Bobs instructions, I now have no more Vapor Loc.
FACT: My one owner LS-5 never got hot or had vapor loc. So what changed.
I had a BAD Eaton Fan clutch.
Fact #2: 1970 " A " body Chevelles all models had an Airflow Ducted engine bay. What the hell is that? I means, All the air that enters the engine bay is FORCED to EXIT ( By road speed or by the engine powered exhaust fan.)
Fact#3: A 1970 engine bay is designed to have the Super Heated Air Exit at the rear of the Lower right & Lower left cast Iron manifolds.
Fact #4: Changing any factory under-hood installed items (rubber seals and such) , So when you re/engineer your engine bay cooling system, And you also think a lot of what this guy just is a big load of Bull Sh!T.
All this stuff about duct work and sealed off engine bay stuff and moving " X " number of cubic feet of air per min. sounds fishy.
When your home A/C or your furnace is running. Use caution !
Remove the blower belt, ( You better have " Super Heat switches working " And then lets talk about Air Flow and Duct work.
Just some trivia, From an old Guy.
Bob
P.S. So you know, My B.I. law Bill was a boss at FORD the Wayne Assmb. plant for 37 years. The Bob guy I speak of was a Thermal Engineer for Chevrolet for 39 years. It is not verbatem, But close.


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1970 SS LS-5/M-22 El Camino- Org. Owner-AACA 2016-Senior Grand National Winner---MCACN-GOLD-2013
1970 ( FRAUD) SS 468 Station Wagon - Driver.
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post #17 of 24 (permalink) Old Dec 22nd, 17, 8:52 PM
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Re: Return fuel line on 1970 el Camino

A lot of history and trivia but the original question has not been answered.
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post #18 of 24 (permalink) Old Dec 22nd, 17, 8:58 PM
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Rame
 
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Re: Return fuel line on 1970 el Camino

Quote:
Originally Posted by Robinls5 View Post
Not sure about other 1970 SS 454s-with a 4 speed. The 454 I have has the three port fuel pump. My 454 has no charcoal canister.
I have a question? If you do not have a charcoal canister attached to your 1970- SS 454, What happens to the fuel VAPORS ?
We all know they "do not" exit to the Atmosphere, My question is, Where do the fuel vapors in the fuel tank " GO " on a 1970- LS-5 ?
The answer is .................................................. ...................... ?

Bob
Trivia:
The 1/4" port on the three port pump. To make my 1970 Sta.Wgn. ( Driver ) 454 Engine look like a Real factory LS-5 with the LS-5 -3 port pump.
I attached a piece of rubber hose to the fuel pump and then shoved a piece of old brake line into the other end of the rubber hose installed the correct spring clamps, Then I shoved it back into the frame rail. NOW my fuel system " LOOKS " like a factory LS-5.
My FRAUD car ( with papers to prove it) SS 454 Sta. Wgn. has been driven over 38.000 miles, And so far I have not seen any fuel come out of the small line ( That is laying on the frame, and goes nowhere. beside the org. 5/16" -307 fuel line,) On my 3 port long canister fuel pump.
Also , For a driver / Cruiser, my 468 runs and operates just fine on the org. 307-5/16" fuel line.
They go out the vent in the gas cap, not sure about 70 but 69 and later had vented gas caps and with a full tank on hard take off or right turns (Camino) fuel would spill out the tank.

.
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post #19 of 24 (permalink) Old Dec 22nd, 17, 9:20 PM
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Rame
 
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Re: Return fuel line on 1970 el Camino

Quote:
Originally Posted by Robinls5 View Post
Some more trivia from an old guy:
What does the so called term vapor lock mean? Think about this: When you boil water it turns to steam or VAPOR, When you boil Brake Fluid it turns to VAPOR. In 1962 drag racing my C/G 38 Chevy. At the end of the 1/4 I had NO BRAKES. Kill the engine and in a few seconds I had a full pedal.
Cause: Headman Headers blowing hot exhaust on brake line.
When you boil gasoline it turns to VAPOR. A 7040205 will no operate on VAPOR, Must have liquid.
So I Call my Brother in law Bill, From Mich, He says call my friend BOB, I call Bob and answer many questions for this Bob guy. He tells me on the phone the problem with my 70 454. So I do what this Bob guy tells me to do.
After I follow Bobs instructions, I now have no more Vapor Loc.
FACT: My one owner LS-5 never got hot or had vapor loc. So what changed.
I had a BAD Eaton Fan clutch.
Fact #2: 1970 " A " body Chevelles all models had an Airflow Ducted engine bay. What the hell is that? I means, All the air that enters the engine bay is FORCED to EXIT ( By road speed or by the engine powered exhaust fan.)
Fact#3: A 1970 engine bay is designed to have the Super Heated Air Exit at the rear of the Lower right & Lower left cast Iron manifolds.
Fact #4: Changing any factory under-hood installed items (rubber seals and such) , So when you re/engineer your engine bay cooling system, And you also think a lot of what this guy just is a big load of Bull Sh!T.
All this stuff about duct work and sealed off engine bay stuff and moving " X " number of cubic feet of air per min. sounds fishy.
When your home A/C or your furnace is running. Use caution !
Remove the blower belt, ( You better have " Super Heat switches working " And then lets talk about Air Flow and Duct work.
Just some trivia, From an old Guy.
Bob
P.S. So you know, My B.I. law Bill was a boss at FORD the Wayne Assmb. plant for 37 years. The Bob guy I speak of was a Thermal Engineer for Chevrolet for 39 years. It is not verbatem, But close.
I do agree with a lot of that, I'm sure people will poke a bit at your wording, but I can see where you are going with it,(I'm not very good at the wording as well). But the question at hand is about modifying old cars to work with parts they weren't even designed for, so sometimes it's back to basics or just pure testing to get them right or better. So good input on the way the factory system worked but lets be honest, they didn't always work very well back then even when they were new.

.
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post #20 of 24 (permalink) Old Nov 1st, 18, 1:53 PM
 
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Re: Return fuel line on 1970 el Camino

If one's '70 big block was assembled for sale in California, those had the 3 'port' mechanical pumps, otherwise usually two.
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post #21 of 24 (permalink) Old Nov 2nd, 18, 8:30 AM
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Re: Return fuel line on 1970 el Camino

You can just tee the supply side going to the carb and run it back to the tank using 1/4" tubing..
I had all kinds of smell and bogging issues until I switched tanks to the one with the three ports at the top front. I blocked two and ran a looped hose to the middle with a gas filter on the end.. You could run your return into one of those..
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post #22 of 24 (permalink) Old Nov 4th, 18, 12:35 AM
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Bob
 
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Re: Return fuel line on 1970 el Camino

My question is, On my 70-LS-5//M-22 El Camino, Where do the fuel tank vapors go?
Bob


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1970 SS LS-5/M-22 El Camino- Org. Owner-AACA 2016-Senior Grand National Winner---MCACN-GOLD-2013
1970 ( FRAUD) SS 468 Station Wagon - Driver.
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post #23 of 24 (permalink) Old Mar 22nd, 19, 8:21 PM Thread Starter
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Re: Return fuel line on 1970 el Camino

Now that it's been a while I'm back to this. I went with an Edlebrock sump, no return required, for my F.A.S.T. EFI. It's working fine. There is a vent port on the unit, the tech said I could route it into the return line from the charcoal canister. I did that, but now I have what seems like higher pressure in my fuel tank. When I take off the cap it seems way too much. I spent some time on the internet (of all places to go for information!) and most of them don't seem to know the difference between pressure and vacuum.

I'm thinking I should put the vacuum canister back the way it was and add the return line and use it for the vent for the sump.

Anyone think this is a bad idea (or unnecessary, that works too!)?

Thanks.

"Let not the sands of time get in your lunch..." Monty Python
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post #24 of 24 (permalink) Old Apr 1st, 19, 12:34 PM
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Re: Return fuel line on 1970 el Camino

I'm doing a 5.3 swap and I intend to use all evap stuff from the donor truck. My buddy told me he could smell gas when I had the car parked in the garage so, ya, I believe using the charcoal canister is a good thing.
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