Author Topic: Fuel vaporizing issue  (Read 6538 times)

Offline ff6849

  • Jr. Member
  • **
  • Posts: 181
Fuel vaporizing issue
« on: March 04, 2013 - 08:29:27 AM »
I just got my car back together, with only about 500 miles on the motor. The car runs great no overheating problems, oil pressure holding at 70-75psi. I have one of those glass style fuel filters right before it goes into the carb inlet, when cruising the car other day sputtered and died I could see the fuel boiling in the filter.  Once the car cooled down it started backup. But it has been an ongoing problem all this weekend. I have a metal canister fuel filter just before the pump too.  I have the original steel lines from the tank, and using rubber from the pump to the car. The motor doesn't run hot, but my headers are throwing off a lot of heat.  And to make things more difficult I live in a extremely hot desert climate so it going to get  worst as spring and summer approach. It was 85' degrees this weekend the car will summer temps of 110'

I have a stock bottom end 440 hp block out of 1968 charger, in a 1973 Cuda
915 heads
TTI  1 3/4 headers
Holly SD manifold
750cfm Edelbrock  carb
Carter mechanical fuel pump (factory style)
COMP  Xtreme Energy Cam #23-224-4
Hughes Roller Rockers
MSD ignition

Some suggestions I been told so far are:
Holley Blue pump or equivalent at tank to help push the fuel through the mech pump
Just omit mech pump and go electric with a return line and regulator
Upgrade fuel line to 3/8 vs stock 5/16

*stop messing with old technology and get a FAST EFI system (budget issue)

Any advice to help me would be appreciated
(__________]]]]]}~~~~

73 440 Cuda'
915 heads (mild head work, stock bottom end 10/9:1 compression)
A518 2600-2800 Stall
4.10 rear gear
TTI headers with 3' exhaust with  X pipe 
comp XE274H cam
Hughes Roller Rockers
Holley Sniper EFI
Holley Street Dominator intake
MSD ignition




Offline nqkjw

  • Full Member
  • ***
  • Posts: 512
Re: Fuel vaporizing issue
« Reply #1 on: March 04, 2013 - 09:00:54 AM »
Electric pump and return line (full flow system) WILL cure it.

Delete the filter before the pump.Your mechanical pump will struggle trying to deliver through 2 filters.
Burnouts are cool but Traction is the Action

Offline cudabob496

  • Sr. Resident
  • ******
  • Posts: 8024
Re: Fuel vaporizing issue
« Reply #2 on: March 04, 2013 - 05:40:03 PM »
Aluminum radiator to help engine run cooler. Summit has them under $200.
Vented hood/engine bay to remove heat better.
Black foam pipe insulation from hardware store for fuel line.
160 degree thermostat

ditching the first filter may help solve the problem.

whats your fuel pressure?
« Last Edit: March 04, 2013 - 08:00:25 PM by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline ff6849

  • Jr. Member
  • **
  • Posts: 181
Re: Fuel vaporizing issue
« Reply #3 on: March 04, 2013 - 05:42:11 PM »
how would one vent the hood......
(__________]]]]]}~~~~

73 440 Cuda'
915 heads (mild head work, stock bottom end 10/9:1 compression)
A518 2600-2800 Stall
4.10 rear gear
TTI headers with 3' exhaust with  X pipe 
comp XE274H cam
Hughes Roller Rockers
Holley Sniper EFI
Holley Street Dominator intake
MSD ignition

Offline 4 speed fish

  • Full Member
  • ***
  • Posts: 849
Re: Fuel vaporizing issue
« Reply #4 on: March 04, 2013 - 05:59:19 PM »
I used a vented gas cap and the single vent tube from the gas tank thru the trunk into the frame rail.Never had a problem with vapor lock.

Offline drewcrane

  • Sr. Member
  • ****
  • Posts: 1298
Re: Fuel vaporizing issue
« Reply #5 on: March 04, 2013 - 06:39:57 PM »
It gets hot here in Denver in the summer mid 80,s to 100,s plus so this is what I did




Just omit mech pump and go electric with a return line and regulator
Upgrade fuel line to 3/8 vs stock 5/16 use   old stock line for return line

Offline cudabob496

  • Sr. Resident
  • ******
  • Posts: 8024
Re: Fuel vaporizing issue
« Reply #6 on: March 04, 2013 - 08:27:58 PM »
how would one vent the hood......

Well, you can also vent the eng bay by removing those flaps over the wheel wells. As far as venting the hood, I have
a fiberglass hood, so putting in holes was easy. I'll post a picture. Keep in mind that the portion of the hood near the
windshield is under positive pressure.  Would look weird maybe, but a backwards hemi scoop might work.  There's probably
1000+ ways to vent a hood (ie put holes in it).
« Last Edit: March 05, 2013 - 08:22:48 AM by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline 72cudamaan

  • Resident
  • *****
  • Posts: 3248
Re: Fuel vaporizing issue
« Reply #7 on: March 04, 2013 - 09:05:57 PM »
If the fuel is boiling then you might try wrapping the headers  with an insulator wrap. Is your fuel line too close to the headers?
If the engine is running cool enough then it must be getting hot from the exhaust. What kind of fan system are you using?
If I cant fix it, it's broke
 
Andy  (phukker whither)

Offline ff6849

  • Jr. Member
  • **
  • Posts: 181
Re: Fuel vaporizing issue
« Reply #8 on: March 04, 2013 - 09:52:46 PM »
a stock clutch fan, with 160 thermostat   
(__________]]]]]}~~~~

73 440 Cuda'
915 heads (mild head work, stock bottom end 10/9:1 compression)
A518 2600-2800 Stall
4.10 rear gear
TTI headers with 3' exhaust with  X pipe 
comp XE274H cam
Hughes Roller Rockers
Holley Sniper EFI
Holley Street Dominator intake
MSD ignition

Offline cudabob496

  • Sr. Resident
  • ******
  • Posts: 8024
Re: Fuel vaporizing issue
« Reply #9 on: March 04, 2013 - 10:13:07 PM »
a stock clutch fan, with 160 thermostat

have a good fan shroud?
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline jimynick

  • Resident
  • *****
  • Posts: 4512
Re: Fuel vaporizing issue
« Reply #10 on: March 04, 2013 - 10:39:24 PM »
The old school way was to wrap the fuel line in aluminum foil; don't use foam because it's a fire hazard you don't need. Buy and install one of the aluminum plates that mount under the carb and you may want to consider one of the plastic or wood (yes, really) carb spacers as well. The advice to wrap the headers is good advice, too. Good luck.  :thumbsup:

Offline cudabob496

  • Sr. Resident
  • ******
  • Posts: 8024
Re: Fuel vaporizing issue
« Reply #11 on: March 05, 2013 - 07:29:23 AM »
The old school way was to wrap the fuel line in aluminum foil; don't use foam because it's a fire hazard you don't need. Buy and install one of the aluminum plates that mount under the carb and you may want to consider one of the plastic or wood (yes, really) carb spacers as well. The advice to wrap the headers is good advice, too. Good luck.  :thumbsup:

Hmmm, I'll have to put a match to a piece of that black pipe foam (insulation) I've put on my fuel line (not the actual fuel line foam), and see what happens. I have the foam on the rubber fuel line from the mech fuel pump to within a few inches of the carb.

Later that day: yep, burns slowly, but mostly melts! Of course, that will be nothin, compared to my fiberglass hood!!
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline 73EStroker

  • Sr. Member
  • ****
  • Posts: 1343
Re: Fuel vaporizing issue
« Reply #12 on: March 05, 2013 - 07:58:19 AM »
Get rid of the glass filter -they can break and have caused many fires. Use metal cased ones.

Wrap the fuel lines with fire sleeve. Also if you are not concerned about originality then install a fuel recirculating return system, preferably with an electric pump. I set up mine with 3/8 in and 3/8 return, no fire sleeve ( going to do that this year) and no heat soak issues even above 100 deg f.
Good luck.
Barry (Salmon Arm)

Offline brads70

  • C-C.com Expert
  • ********
  • Posts: 18747
Re: Fuel vaporizing issue
« Reply #13 on: March 05, 2013 - 08:02:34 AM »
I agree about the hardware store pipe insulation. It is a fire hazzard, when it shows up on a stock car ( I'm a tech inspector at a local track) I make them remove it . Some racers, usually rookies actually try to use it for roll bar padding! :eek4: Also that glass filter is a worse fire hazzard!  They break/rattle loose! Glass or plastic fitlers are a no no!  :nono:
 I wouldn't suggest wraping the header either as it will drastically shorten it's lifespan.
As mentioned the electric fuel pump and return line set up will be the best bet. That's what I did, only don't use a Holley pump, they are REALLY noisy. Use a pump with a Gerotor design  they are much quieter.
 I used a Mallory pro comp 140 series , much quieter! :2thumbs:

Here is a neat link to describe the different pump designs in case you were wondering?
http://www.simerics.com/simulation_gallery_pd_pump
Brad
1970 Challenger 451stroker/4L60 auto OD
Barrie,Ontario,Canada
Proud to own one of the best cars ever made!!!!!

My restoration thread 
http://www.cuda-challenger.com/cc/index.php?topic=59072.0
 My handling upgrade post
http://www.cuda-challenger.com/cc/index.php?topic=73985.0

Offline cudabob496

  • Sr. Resident
  • ******
  • Posts: 8024
Re: Fuel vaporizing issue
« Reply #14 on: March 05, 2013 - 08:24:46 AM »
I used a vented gas cap and the single vent tube from the gas tank thru the trunk into the frame rail.Never had a problem with vapor lock.

Ya, maybe all thats needed here is a vented gas cap!
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000