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Topic: carb boiling

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carb boiling (1/27)
 10/22/12 10:26pm
laryred77
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Linesville, PA - USA

Vette(s):
1977 red coupe/T tops red int. 1999 magnetic red convertible 6 spd manual


Joined: 6/25/2012
Posts: 26

 anyone using carb shields

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Re: carb boiling (2/27)
 10/22/12 11:05pm
danascar
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Germansville, PA - USA

Vette(s):
1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. . 1999 C5 Convertible, 6 speed, Atomic orange, Oak interior.


Joined: 1/28/2010
Posts: 858

Mine is on the workbench waiting to be installed. Know of at least 3 people with them on and as far as I hear they all like them and say they work.

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DanT

Re: carb boiling (3/27)
 10/23/12 12:12pm
aceintheholeLifetime Member
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Manteca, CA - USA

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1978,two tone,Metalic Rootbeer & gold 1975 L48 4 speed


Joined: 11/20/2005
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 I always feel a little bad about admitting it but, this term is unfamiliar to me. Can anyone step up and educate me ?  Thanks.

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Jimmy B.
Just can't wait to get on the road again.

 
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Re: carb boiling (4/27)
 10/23/12 12:24pm
danascar
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Germansville, PA - USA

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1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. . 1999 C5 Convertible, 6 speed, Atomic orange, Oak interior.


Joined: 1/28/2010
Posts: 858

aceinthehole said:  I always feel a little bad about admitting it but, this term is unfamiliar to me. Can anyone step up and educate me ?  Thanks.

Another term for vapor lock, or the carburetor getting so hot that the gas in it boils off and causes the engine to stall from the lack of gas....not good Censored The shields block the heat from the manifold getting to the carb.


 



|UPDATED|10/23/2012 9:24:13 AM (AZT)|/UPDATED|


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Re: carb boiling (5/27)
 10/23/12 12:25pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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My experience with them has not been good. They always seem to create vacuum leaks that just won't go away. The ones we used were the thin aluminuminum ones, and no matter what we did, we could never get them to seal properly. A better choice is to use the thick, phenolic plastic spacers, as they insulate the bottom of the carb from heat much mo betta. Of course, on a Corvette, making the carb sit higher creates it's own problems.

Jimmie, the discussion is about using a heat shield(thin piece of alum. sheet) under the carburetor in an attempt to keep some of the heat from the intake manifold from being absorbed by the carb, which can cause the fuel in the carb to boil. Thumbs Up




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Re: carb boiling (6/27)
 10/23/12 12:36pm
aceintheholeLifetime Member
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Manteca, CA - USA

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1978,two tone,Metalic Rootbeer & gold 1975 L48 4 speed


Joined: 11/20/2005
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 Thank you gentlemen, that makes sense. Don't believe I've ever had that problem, and our best lessons are learned from experience. Thanks very much guys.

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Jimmy B.
Just can't wait to get on the road again.

 
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Re: carb boiling (7/27)
 10/23/12 12:44pm
aceintheholeLifetime Member
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Manteca, CA - USA

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1978,two tone,Metalic Rootbeer & gold 1975 L48 4 speed


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 Joel, the way you come up with those pics so quickly is phenomenal buddy Thumbs Up. I don't remember seeing one before so a pic is worth a thousand words ( or at least a hundred Wink ). 

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Jimmy B.
Just can't wait to get on the road again.

 
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Re: carb boiling (8/27)
 10/23/12 4:49pm
NorskyLifetime Member
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West Burke, VT - USA

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"The Toy" was having hot start issues that were solved by a Mr. Gasket set of aluminium and plastic spacers.  I used about 3/4 of the pack which insolated the carb just fine and didn't cause the air cleaner to clang on the hood.  The carb now stays just warm to the touch rather than too hot to touch with a bare hand.

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Re: carb boiling (9/27)
 10/24/12 10:44am
laryred77
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Linesville, PA - USA

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1977 red coupe/T tops red int. 1999 magnetic red convertible 6 spd manual


Joined: 6/25/2012
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I just know I have to do something to help the hot starts and also after long ride I put car in garage I could hear gas in carb boiling so thanks for your posts.
Re: carb boiling (10/27)
 10/24/12 11:55am
MikeMc71
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Tucson, AZ - USA

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1970 White L-46 Air Roadster, 1971 White LT1 Coupe, 1971 Red Auto Air Coupe, 383 stroker, 430 HP, 2002 Millennium Yellow Auto Coupe


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What I did to fix this problem in my wifes car was to block the water port under the carb in the intake manifold, and it really helped. Of course, being in Arizona we really don't have to worry about too much cold, but we do worry about too much heat. I have never had to use a carb shield on a Corvette we have owned here yet, and we drive them in 100+ degree temps.

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Re: carb boiling (11/27)
 10/24/12 1:32pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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Cast iron intake mannyfolds will hold a LOT of heat in them, and transfer it to the carb. One way to help keep the heat down is to block off the heat riser passage in the intake. This might make your cold weather starts a little more aggravating, but it would also help with the fuel boiling issues. Another thing is to check the quality of the fuel...lower grade fuel will tend to percolate more easily than better quality fuels.






|UPDATED|10/24/2012 10:32:05 AM (AZT)|/UPDATED|


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Joel Adams
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Re: carb boiling (12/27)
 10/24/12 8:39pm
Almond81Vette
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Stanley, NC - USA

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1981, dark blue w/carmel interior. 350 stock, auto tranny, Q-jet carb, ECM box


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I agree with Adam on the gas we get today, with the "blend" not being no where close to what these cars were set up to use but what is one to do when they tweak the fuel as they do. Had one carb company tell me if can get pure gasoline without the ethnol and higher octane will help.......if can find and can pay the price, otherwise life is what it is. I know on my '81 since the engine compartment is packed from the factory, when been on the road and temps are up or outside air is hotter, when I stop I just pop the hood and let the hot air escape and that seems to help....but only if you can leave the hood up where ever you are stopping.

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Re: carb boiling (13/27)
 10/24/12 9:24pm
KDADDY79
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Dutchess County, NY - USA

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Luckily I've never had this issue in mine. (Knock on wood.)

I do agree with Almond81's idea of opening the hood. I'm in the habit of opening the hood when I first shut it off. I do this all the time to avoid heat issues and also I think I'm saving the paint on my hood from too much heat underneath.
 
Kevin
Re: carb boiling (14/27)
 10/25/12 3:44pm
VikingVette
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Greer, SC - USA

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1978 Black with Viking mural painted under hood AM/FM/CB radio, T-top and a 2013 Cyber Gray Grand Sport Coupe, 2LT for my daily driver


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I too always open the hood when I park after a long ride.  A few stations here in SC are goingto 'pure gas' with no ethanol.  My C5 loves that stuff and I actually do get a little bit better mileage.  In my '78, I have no idea what mileage I get, but that too seems (probably just my imagination) run a bit better on the pure gas.  I have also heard (per Dr. Adams comments) that a ceramic, or phenolic spacer, is better than a metal spacer. 

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Re: carb boiling (15/27)
 10/31/12 4:41pm
rod7515Lifetime Member
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Red Lion, PA - USA

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1974 White 350 Corvette, TH400 Automatic 1972 Tangerine /Go Mango Convertible 383 Stroker, 2004r Automatic


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As Joel said in his earlier post, use the heat riser block off gasket set.It will probably not effect your cold starting as much as it may keep the choke from going off quick enough and could cause a rich fuel issue when cold. When I first used this gasket set I wired my choke open which made starting cold much harder but I added an electric choke kit which cured that problem.  Heres a pic of the felpro gasket Number.
Best of luck
Rodney
 
 
(large picture modified to a clickable link - Norsky)


|UPDATED|10/31/2012 1:41:35 PM (AZT)|/UPDATED|


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Re: carb boiling (16/27)
 10/26/12 12:27am
dapperdan
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COLUMBUS, NC - USA

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2011 Grand Sport Coupe, 6-speed 1977 Coupe L82, 4-speed


Joined: 8/19/2012
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Does your ride have the original air cleaner with all of the components connected and operating?  The big air cleaner is actually a heat sink and it tends to take up some of the heat in the area of the carburetor.  Also, with the  original air intake, the carb gets cool air forced into its throat, which is always better than hot air.  If a car has an after market cleaner with none of the engineered components, the carb is getting hot air during running and the cleaner does not have the mass to act as a heat sink.  I wonder if owners who have trouble with boiling gas, have modified the car with a different air cleaner?  The original design acts to warm the car up faster, thus the carb, but the intake flap opens and the exhaust heat exchanger closes, so that the temperature is controlled as per design.  Just wonder about the addition of different air cleaners as the cause of boiling in the carb.

Another suggestion on dealing with the current gasoline (ethanol added) is the use of naphthene in the gas.  Some brand of moth balls are 100% pure naphthalene.  One of these moth balls per gallon of gas will act pretty much like leaded gasoline.  You have to crush them up to get them into the tank on the cars with the small gas openings.  This also helps with cooling the exhaust valves on cars that have the softer valve seats.


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Re: carb boiling (17/27)
 10/26/12 3:49pm
73shark
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Overland Park, KS - USA

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1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
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FWIW from an internet source: 

Yes, mothballs will slightly assist the octane rating of gasoline. HOWEVER, in that grain of truth there lurks the potential for disaster. One must use very few mothballs (naphthalene only) because the ratio of carbon to hydrogen in the molecules makes for a very dirty burning fuel. Too many mothballs and your engine will load up with carbon deposits -- very bad news in the performance department.

Also DO NOT mistakenly use moth crystals (paradichlorobenzene). The chlorine atoms in this material becomes HCl upon combustion. Hydrochloric acid (HCl) is very destructive to engine internals.

Finally, unless your engine is high compression and in need of high octane fuel, enhancing the octane rating of the fuel over what is required is simply a waste of money. High octane fuel burned in an engine designed for lower octane fuel does not increase engine power.


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1973 L-82 4 spd

Re: carb boiling (18/27)
 10/26/12 4:20pm
laryred77
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Linesville, PA - USA

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1977 red coupe/T tops red int. 1999 magnetic red convertible 6 spd manual


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Posts: 26

Here is an update :Installed Mr.gasket heat shield today on my '77 I couldn't be happier I went for long ride (probably last one this year) to get temp up got home pulled in garage opened hood and could actually put my hand on top of air cleaner before you could cook your supper. So thank you everyone once again for your help what a great site.
Re: carb boiling (19/27)
 10/26/12 4:26pm
danascar
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Germansville, PA - USA

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1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. . 1999 C5 Convertible, 6 speed, Atomic orange, Oak interior.


Joined: 1/28/2010
Posts: 858

laryred77 said: Here is an update :Installed Mr.gasket heat shield today on my '77 I couldn't be happier I went for long ride (probably last one this year) to get temp up got home pulled in garage opened hood and could actually put my hand on top of air cleaner before you could cook your supper. So thank you everyone once again for your help what a great site.

What combination of plates did you use Question

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Re: carb boiling (20/27)
 10/26/12 7:55pm
laryred77
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Linesville, PA - USA

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1977 red coupe/T tops red int. 1999 magnetic red convertible 6 spd manual


Joined: 6/25/2012
Posts: 26

I only used 2 of the alum. plates 
Re: carb boiling (21/27)
 10/26/12 10:36pm
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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Clap Thumbs Up
Glad it worked out well for ya!


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Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Re: carb boiling (22/27)
 10/31/12 8:18am
nosal1
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Dunedin, FL - USA

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1980 Corvette Torch Red with Gold metallic 370HP/350 CU.IN.Turbo 350 w/shift kit.Originally CA.Car with 305 CU.IN.


Joined: 3/21/2006
Posts: 262

Hello All,  On occasion while living in California I would make a run north and south to visit family,usually distances of 225 0r more one way,I would "pop" the hood of the Vette enough that air would pass through the engine and out of the tight compartment and reduced the amount of heat collected in the engine bay. I would cruise at 80 -90 mph and the hood stayed where it laid on the the locks and engine temp stayed at 190 degrees.When I got to where I was going to be for a while I opened the hood and allow the engine to breath..Still do this here in Florida,however the runs are shorter and slower..

 

Re: carb boiling (23/27)
 10/31/12 10:27am
dapperdan
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COLUMBUS, NC - USA

Vette(s):
2011 Grand Sport Coupe, 6-speed 1977 Coupe L82, 4-speed


Joined: 8/19/2012
Posts: 42

I am just curious.  Does your ride have the factory air cleaner with all components connected and functioning as designed???  My 1977 L82 is completely original and I live in the south.  Have had no instances of "carb boiling."

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Re: carb boiling (24/27)
 10/31/12 4:36pm
nosal1
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Dunedin, FL - USA

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1980 Corvette Torch Red with Gold metallic 370HP/350 CU.IN.Turbo 350 w/shift kit.Originally CA.Car with 305 CU.IN.


Joined: 3/21/2006
Posts: 262

Here's an under the hood picture.


 
(Large picture modified to a clickable link - Norsky)




|UPDATED|10/31/2012 1:36:11 PM (AZT)|/UPDATED|
Re: carb boiling (25/27)
 10/31/12 11:21am
nosal1
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Dunedin, FL - USA

Vette(s):
1980 Corvette Torch Red with Gold metallic 370HP/350 CU.IN.Turbo 350 w/shift kit.Originally CA.Car with 305 CU.IN.


Joined: 3/21/2006
Posts: 262

To answer the question of whether or not I have the stock air cleaner etc. on my car the picture above this is the answer.I only have use the stock cowling and made the Stainless steel plate to direct the air to assist in cooling as oppose to the two (in my engine) snorkels normally of '80 Vette engines.Sorry to taken two spaces up with the answer,however could not add text to the last reply.Have a great day.    Sal C

Re: carb boiling (26/27)
 10/31/12 11:56pm
dapperdan
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COLUMBUS, NC - USA

Vette(s):
2011 Grand Sport Coupe, 6-speed 1977 Coupe L82, 4-speed


Joined: 8/19/2012
Posts: 42

I have been wondering about owners who are experiencing carb boiling and whether they have removed the engineered air cleaner system that was on the car new.

With a cleaner such as yours, the engine is breathing hot air.  Cold air is more dense and is always a better option for any combustion engine.  That is why superchargers have a cooler to make sure that the engine is getting the dense air.

Also, the after market air cleaner is not acting as a heat sink for the carburetor.  It does not have enough mass.  And the original set up had scoops that routed air from outside the engine compartment (cooler air) into the throat of the carb. 


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Re: carb boiling (27/27)
 11/3/12 3:13pm
F4GaryGold Member
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Grapevine, TX - USA

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1972 LT-1 convertible with factory air.


Joined: 8/26/2006
Posts: 1406

There were no snorkles on the LT-1s.  I've noticed that if my car sits after a drive, when I start it up, the engine won't rev on one push of the gas pedal.  Kinda have to goose it a few times.  Then after a minute or so, it runs normal.  It's as if the ethanol in the gas causes the gas in the hot lines to boil or something.

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