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Boiling Gas I think

2K views 22 replies 14 participants last post by  Jan Ove 
#1 ·
I drove my vert today and I'm starting to get tired of a problem when the car is warm.

Say I'm driving and the car is at temperature. I stop somewhere and park the car from anywhere from 5 minutes to 1 hour. The car will take many cranks to start. It will barely idle or even run if my foot is not in the gas. After about 1-2 minutes (which I think is about how much time it takes for new gas to replace the boiling gas), the car runs great.

Also when it does get started, a plume of black smoke pours out the back.

Is this a boiling gas problem?? It's a 351C with a Edlebrock carb on it. No spacer between the carb and stock intake.

Any ideas / suggestions? thanks
Z
 
#4 ·
I understand that. It does not smoke when it runs, just when I start when it's hot. After the start, no more smoking. Thanks though!
 
#6 ·
Had the same problem on my Cleveland a while ago - I could actually hear the gas boiling in the carb. I also rebuilt and at the same time put in a phelonic (sp?) spacer (yes, the fiber composite one.) No problems since.

Aluminum spacer seems somewhat pointless to me - despite the gaskets, I would think it could still transmit heat to the base?
 
#7 ·
Same symphtoms i had on my car, and it got conciderable better after i installed a spacer, even tho i installed a alu spacer
 
#11 ·
I suppose a Edelbrock RPM Airgap intake wouldn't need a spacer,

I'm running a regular Edelbrock Performer intake in my cat, the Performer RPM Airgap would have been my choice now, due to there is the gap between the valley and the runners to keep the fuel cooler, and i wish i had known better back when i purchased it, and i would have gotten the RPM instead of the regular one
 
#12 ·
You will need the spacer with the cast iron manifold. there is an exhast passage that comes right up under the bottom of the carb. It would be a miracle for it nor to boil. I am suprised that you don't have a vacuum leak there... An air gap would sure be cool if it fits under the hood..
 
#13 ·
I drove my vert today and I'm starting to get tired of a problem when the car is warm.

the car is at temperature. The car will take many cranks to start. I

Also when it does get started, a plume of black smoke pours out the back.

Any ideas
Z
I have seen a sticking float (or bad needle) do this. It floods the engine when you shut off the key by leaking fuel from the carb into the intake. If you let it set for hours than the fuel will evaporate and not be a problem. If you start up the car right away, there will not be enough time to accumulate as much fuel to flood the engine (improper fuel/air mixture) A hole in the bottom of the fuel bowl would do the same thing.

Stage your wrenches at the car, start car to fill carb bowls. Stop car and remove 4 carb mounting bolts. Raise carb slightly from intake and shim with something to hold it level. Carb can still be on studs. Slide a sheet of paper between carb and intake and check for fuel droplets. If you don't find any, I just wasted a little of your time and no money. John
 
#14 ·
Zogman, Do you have ANY backfiring issues? Sounds alot like my cats problem but I also have the backfiring prob.I also have a 351 c 4v I believe that my car has a performer intake, and a holley 750 w/vacuum secondaries.So I would need the spacer too? How much do they run ?
 
#15 ·
Yeah Zoli, the phenolic spacer would definately help if not cure that problem. Hood clearance could be an issue though. Measure carefully.
 
#16 ·
Try the gas cap. Mine did that and I found my gas cap was not venting, making a vapor lock type problem

Mike .02
 
#17 ·
The spacers are cheap - about $30 and come in a number of sizes. I have the alum. Edelbrock Performer intake and first tried a 1" plastic spacer. Way too big and it did not seem to seal well. I then went down to a 1/2" composite spacer which seems to both take care of the heat and keep the height down. (Although I then put on a 3" aircleaner to just poke through the opening for my hoodscoop. The wingnut clears the scoop by about 1/8".)

Most speed shops carry the spacers - I think I got mine from Summit - something like this:

http://store.summitracing.com/partd...839063+4294873482+4294873429+115&autoview=sku
 
#19 ·
I ordered the 1" phenolic spacer that Atomic Bob refered to in his link. I'm paying $34.00 from my local full service autoparts. I'm hoping the 1" is not too tall but I don't think it will be an issue.

In regards to performance, I imagine it should help a bit. I can' wait to see if it fixes my problem.

My wife says I have lots of problems but I just want the boiling gas problem fixed right now. I have priorities. Thanks for all of your help. I will fill you guys in tomorrow if it helps.

Z
 
#20 ·
Hard Starting

I too had problems with my 68 cougar with a 390. Last winter I installed a 1 inch phenolic spacer and an aluminum heat shield. I also installed an electric fuel pump. The car is a new car, starts get after it is hot. You can put your arm through the window and turn the ignition switch and it fires right up. No smoke!

I have an Edelbrock Performer RPM FE air intake, a Demon 750 carb, and a Holley Elec. Fuel Pump
 
#21 ·
Boiling problem

Call edelbrock and give them the type of carb and intake you have. They make rubber gaskets for this problem. When you turn your car off the heat from your engine goes up and cooks your carb. A rubber gasket between the carb and intake will lower any heat transfer. An edelbrock tech will tell you which gasket will fit your application. -D:1poke:
 
#22 ·
OH MY GOD!!!

I can't believe I lived with this crap for 9 years!!! I put the spacer on and took it for a nice long drive. Pulled into a gas station to fill the pig up and she started right up without any hesitations or smoke out the back. Drove her home and parked her for 15 minutes to give it time to boil but she started right up. WOW!

I'll drive her this weekend to give it a good test but preliminary results are awesome. I'll probably have to get a new air filter element that is 1/2 shorter to make sure the filter stud does not hit the hood.

On a similar note, the car runs better. Little bit better response and revs a bit easier. I wonder if the colder gasoline helps this out. Anyways, thanks for all of your help. I will report at the end of the weekend to let you alll know how big my smile is.

Z
 
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