12-25-2015, 05:31 PM | #1 |
Registered User
Join Date: Jul 2015
Location: Arlington Texas
Posts: 1
|
Big block issues.
I have a 1969 c10 with a 454 in it. I keep having a problem with it vapor locking. I am running an electric fuel pump in the rear and a Holley mechanical. I am running a fuel pressure regulator with a return line and this hasn't changed anything. Any help would be greatly appreciated.
Posted via Mobile Device |
12-25-2015, 05:50 PM | #2 |
Registered User
Join Date: Apr 2013
Location: South Westerlo, New York
Posts: 1,325
|
Re: Big block issues.
I've never had an engine vapor lock so I don't know what the symptoms are but what is it doing to make you think it's vapor lock?
__________________
Thanks, Joe.. 1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB. Last edited by hamjet; 12-25-2015 at 07:39 PM. |
12-25-2015, 07:00 PM | #3 | |
The Older Generation
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,574
|
Re: Big block issues.
Quote:
My old White '67 had a 454 in it and the gas would boil in the float bowls. Same symptoms as vapor lock. I cured it by putting a 3/4 inch Phenolic spacer between the carb and manifold. You can get them about anywhere any more. Jegs, Summit, O'reilys, e-Bay, etc... LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
|
12-25-2015, 07:06 PM | #4 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
|
Re: Big block issues.
Yeah, the spacer is the first thing to try. We have so much hood clearance that it's not an issue (whereas it can be on some vehicles).
Make sure you have proper steel lines (no more than 6" of rubber in the whole truck) too, and that it's not picking up a bunch of heat under the hood. Lose any glass/plastic clear filters. Ideal is steel line right from pump to carb, with filter in-carb. If running an external filter I prefer the ones you can plumb in with hard line like the factory did. If you have headers they shed a ton of heat under the hood where don't want it, so coating or wrapping them can help. The one downside to a return system is you're continually bringing fuel up front, heating it, and returning it to the tank. If you find that it's better when the tank is full (bigger heat sync) maybe you'd be better off with a vanilla fuel system and losing the electric pump? Some people advocate adding the electric pump to cure vapor lock though, so that'd be the last thing I change.
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
12-25-2015, 07:10 PM | #5 |
Senior Member
Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,833
|
Re: Big block issues.
I don't have your answer, but mine big block was starving for fuel on hard throttle.
My 71 Longhorn with original 402 and Quadrajet seems to vapor lock after sitting at idle such as stoplights drive thru's etc. When I take off It vapor locks if I get in the throttle hard. If I back off the throttle, it will pick and go on. I changed the pump to carb fuel line with an inline filter. Put an original steel line on it. Put a 3/4" phenolic spacer under the carb. I raised the float in the Quadrajet and that helped, but It still starves for fuel if it idles very long, creating heat under the hood.. I know none of this helps, but now I am subscribed to the thread.
__________________
other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
12-26-2015, 04:03 AM | #6 |
Registered User
Join Date: Oct 2007
Location: Spanaway
Posts: 8,451
|
Re: Big block issues.
Are ya sure its vapor lock? Non vented fuel cap creating a vacuum in the tank?
__________________
Mike. Swamp Rat build thread : http://67-72chevytrucks.com/vboard/s...d.php?t=595019 72 3/4T 4X4 4" BDS Lift 33" BFG's |
12-26-2015, 06:57 AM | #7 |
Registered User
Join Date: Mar 2015
Location: Fletcher, N.C.
Posts: 309
|
Re: Big block issues.
I like the ...
1-1" phenolic spacer 2-Fuel lines away from header pipes and hot parts of the engine 3-A vented gas cap 4-Closed up rubber fuel line from the tank to the hard line on frame 5-Stopped up or old sending unit sock 6-Improper carb adjustment Ed...
__________________
1970 C/10 350/T5 SWB stepper... 1979 Corvette 350/Auto T-top... 2010 Acura RL... 2015 2500HD Z-71 Silverado... |
12-26-2015, 12:35 PM | #8 | ||
"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,947
|
Re: Big block issues.
Running an electric pump into a mechanical used to be the old school way of regulating pressure, so then add another pressure regulator after that and you might have a wonky system that's having issues. What is your pressure set at? What carb do you have? Also... what is your timing set at?
Gary
__________________
'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
Quote:
|
||
12-26-2015, 03:32 PM | #9 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
|
Re: Big block issues.
One way to sort out venting vs vapor lock is when the tank is full and the truck is cold. It should hit a problem sooner (less air space in the tank) with the tank full if it's a venting issue. And when the truck stops, you should be able to hear a hissing sound when you open the cap.
With a return system it'll take LONGER for the problem to manifest with a full tank because it's a bigger heat sync. Something to think about!
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
12-26-2015, 07:53 PM | #10 |
Registered User
Join Date: Aug 2014
Location: Alabama
Posts: 50
|
Re: Big block issues.
Look at the route of your fuel line. If it's touching anything that carries water you need to move it away from it. I had a 427 vapor lock and the fuel line ran between the block and the water pump. Once I moved it there were no more problems.
__________________
1972 C10 Cheyenne 402/TH350 1985 GMC 1500 Sierra Classic 350/700R 1986 K20 427/NV4500 1986 K20 Sub 406/TH400 "Life's tough.....It's enough tougher if your stupid." John Wayne |
12-26-2015, 08:32 PM | #11 |
Senior Member
Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,267
|
Re: Big block issues.
That was my first thought.
__________________
Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
12-26-2015, 08:34 PM | #12 |
Senior Member
Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,267
|
Re: Big block issues.
Looks good to me.
__________________
Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
12-26-2015, 08:43 PM | #13 |
Senior Member
Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,833
|
Re: Big block issues.
Ethanol blended fuel will vapor lock at lower temp than non ethanol.
__________________
other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
12-27-2015, 10:59 AM | #14 |
Registered User
Join Date: May 2013
Location: Colorado Rocky Mountains
Posts: 263
|
Re: Big block issues.
X2 on the Ethanol blended fuel. I have experienced vapor lock on carbureted trucks that
never had an issue before. All fuel related , the hardware on the engine was all stock. Don't you love when your government / EPA / Corn subsidies dictate what fuel you can buy. Our trucks are built to run on good old gasoline , not some designer fuel blend made for a Corolla. All the Best, Dirk |
12-27-2015, 01:58 PM | #15 | |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
|
Re: Big block issues.
Quote:
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
|
12-27-2015, 04:53 PM | #16 |
Senior Member
Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,833
|
Re: Big block issues.
I email my representatives my opinion of ethanol every now and then.
__________________
other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
12-27-2015, 06:12 PM | #17 | |
Registered User
Join Date: May 2013
Location: WEST PALM FLORIDA
Posts: 1,174
|
Re: Big block issues.
?
Quote:
__________________
68 Long Fleet , ly6 , turbo 350 , 3-5 drop , original paint , front discs 67 Small window , 7 foot bed , tweaked 6.0 LSX 2004R Medium Olive 58 Apache fleet , 235 , offy intake , dual exhaust , 4 on the floor , red/white 69 Long Fleet , Custom , 6.0, 4l60 , AC , Medium Olive |
|
12-27-2015, 11:47 PM | #18 |
Registered User
Join Date: Jul 2015
Location: 2nd left past the stump on a dirt road.
Posts: 2,629
|
Re: Big block issues.
Do not forget the fuel pump that will start it when its cold and run under idle, they go bad, and do no pump fuel under partial to wide open throttle.
|
Bookmarks |
Thread Tools | |
Display Modes | |
|
|