fuel boiling
Burning Brakes
Joined: Jan 2003
Posts: 755
Likes: 32
From: Roswell Georgia
When I check the float level the car should be running or does it matter?
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
I added a stainless shield under my Holley, before the carb got so hot you could not
leave your hand on the carb. for more than 5 seconds,
the heat cross-over was already blocked off.
I installed a SS shield It lowered the carb temperature drastically.
nice and cool, I highly recommennd a shield. 69VETT
leave your hand on the carb. for more than 5 seconds,
the heat cross-over was already blocked off.
I installed a SS shield It lowered the carb temperature drastically.
nice and cool, I highly recommennd a shield. 69VETT
Thread Starter
Instructor
Joined: Nov 2008
Posts: 157
Likes: 0
I ordered the edelbrock 9265 1/3" thick nitrile gasket and this from summit today. Not sure I need both, the holley gasket looks identical to the edelbrock, but I didn't see long studs included in the holley kit so I got both.
I checked to see if fuel was coming out of the accelerator nozzles, and with the lighting in the garage I can't see it, but when I wipe my finger under the nozzles I can feel it. Hopefully this will do it, blocking the heat riser will have to wait for another time. Thanks for everyone's input.
Will this fit with my drop base air cleaner? Probably should have thought of that before now.
I checked to see if fuel was coming out of the accelerator nozzles, and with the lighting in the garage I can't see it, but when I wipe my finger under the nozzles I can feel it. Hopefully this will do it, blocking the heat riser will have to wait for another time. Thanks for everyone's input.
Will this fit with my drop base air cleaner? Probably should have thought of that before now.
Last edited by sonny_burnett; Oct 17, 2009 at 06:14 PM.
Pro
Joined: May 2011
Posts: 722
Likes: 58
From: Karlsruhe (Germany)
Hi,
I have noticed a similar issue with my 3x2 setup the last days. Ok, it is warm, but engine temp is perfect thanks to a Dewitts radiator. I drove the car also in hotter days last year and can´t remember the problem:
There is no fuel coming out of the accelerator nozzles of all 3 carbs at the first (or may be more) shots. Seems that it evaporates. If I give it a shot and soon after again while driving I have no hesistation. But when the secondaries where not in use for a longer time the pumps are empty and need to be pushed.
Is this a known issue? Im wondering why this happens now on all 3 carbs at the same time...andy thoughts?
Btw: engine has around 92°C (nearly 210F) and the carbs have ~25° less temperature.
When they are cold the pumps worke perfect, with the slighliest touch the fuel comes emmidiately out of the nozzles.
I have noticed a similar issue with my 3x2 setup the last days. Ok, it is warm, but engine temp is perfect thanks to a Dewitts radiator. I drove the car also in hotter days last year and can´t remember the problem:
There is no fuel coming out of the accelerator nozzles of all 3 carbs at the first (or may be more) shots. Seems that it evaporates. If I give it a shot and soon after again while driving I have no hesistation. But when the secondaries where not in use for a longer time the pumps are empty and need to be pushed.
Is this a known issue? Im wondering why this happens now on all 3 carbs at the same time...andy thoughts?
Btw: engine has around 92°C (nearly 210F) and the carbs have ~25° less temperature.
When they are cold the pumps worke perfect, with the slighliest touch the fuel comes emmidiately out of the nozzles.
Pro
Joined: May 2011
Posts: 722
Likes: 58
From: Karlsruhe (Germany)
Hi,
I have noticed a similar issue with my 3x2 setup the last days. Ok, it is warm, but engine temp is perfect thanks to a Dewitts radiator. I drove the car also in hotter days last year and can´t remember the problem:
There is no fuel coming out of the accelerator nozzles of all 3 carbs at the first (or may be more) shots. Seems that it evaporates. If I give it a shot and soon after again while driving I have no hesistation. But when the secondaries where not in use for a longer time the pumps are empty and need to be pushed.
Is this a known issue? Im wondering why this happens now on all 3 carbs at the same time...andy thoughts?
Btw: engine has around 92°C (nearly 210F) and the carbs have ~25° less temperature.
When they are cold the pumps worke perfect, with the slighliest touch the fuel comes emmidiately out of the nozzles.
I have noticed a similar issue with my 3x2 setup the last days. Ok, it is warm, but engine temp is perfect thanks to a Dewitts radiator. I drove the car also in hotter days last year and can´t remember the problem:
There is no fuel coming out of the accelerator nozzles of all 3 carbs at the first (or may be more) shots. Seems that it evaporates. If I give it a shot and soon after again while driving I have no hesistation. But when the secondaries where not in use for a longer time the pumps are empty and need to be pushed.
Is this a known issue? Im wondering why this happens now on all 3 carbs at the same time...andy thoughts?
Btw: engine has around 92°C (nearly 210F) and the carbs have ~25° less temperature.
When they are cold the pumps worke perfect, with the slighliest touch the fuel comes emmidiately out of the nozzles.
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,581
How many years since the carburetors were disassembled. The check valve below may have hardened preventing gas from entering the pump assembly.
http://www.jegs.com/i/Holley/510/26-...FSdk7AodGDIAKw
http://www.jegs.com/i/Holley/510/26-...FSdk7AodGDIAKw
Pro
Joined: May 2011
Posts: 722
Likes: 58
From: Karlsruhe (Germany)
Thank you, now I know what these things in my rebuildkit are for.
I had the carb disassembled a half year ago, but never touched the accelerator pumps.
The carb temp has come down now to 52°C which is slightly under the boiling point of the gas, and the pumps are working now as they should. Think it´s really a heat issue. But I am still wondering why I notice this just now after years with no problems.
Hm, well I will keep checking the carb temps, then making me a heat shield or a spacer.
How much will a simple aluminum sheet metal help? (I cant put a larger spacer in there, having not enough space)
I had the carb disassembled a half year ago, but never touched the accelerator pumps.
The carb temp has come down now to 52°C which is slightly under the boiling point of the gas, and the pumps are working now as they should. Think it´s really a heat issue. But I am still wondering why I notice this just now after years with no problems.
Hm, well I will keep checking the carb temps, then making me a heat shield or a spacer.
How much will a simple aluminum sheet metal help? (I cant put a larger spacer in there, having not enough space)
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Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
easy test, put your hand on your carb with engine fully warmed up,
mine was so Hot you could not keep your hand in place, and boiling the fuel off if it sat.
installed a Thermall /Metal sheild with gaskets, on both sides.
The Carb temp dropped almost 100 Degrees, problem solved.
to block the thermal crossover with only carb off, I cut and pinched shut 3/8" stainless tubing.
to block the crossover inlets.
mine was so Hot you could not keep your hand in place, and boiling the fuel off if it sat.
installed a Thermall /Metal sheild with gaskets, on both sides.
The Carb temp dropped almost 100 Degrees, problem solved.
to block the thermal crossover with only carb off, I cut and pinched shut 3/8" stainless tubing.
to block the crossover inlets.
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,581
Gasoline
Thank you, now I know what these things in my rebuildkit are for.
I had the carb disassembled a half year ago, but never touched the accelerator pumps.
The carb temp has come down now to 52°C which is slightly under the boiling point of the gas, and the pumps are working now as they should. Think it´s really a heat issue. But I am still wondering why I notice this just now after years with no problems.
Hm, well I will keep checking the carb temps, then making me a heat shield or a spacer.
How much will a simple aluminum sheet metal help? (I cant put a larger spacer in there, having not enough space)
I had the carb disassembled a half year ago, but never touched the accelerator pumps.
The carb temp has come down now to 52°C which is slightly under the boiling point of the gas, and the pumps are working now as they should. Think it´s really a heat issue. But I am still wondering why I notice this just now after years with no problems.
Hm, well I will keep checking the carb temps, then making me a heat shield or a spacer.
How much will a simple aluminum sheet metal help? (I cant put a larger spacer in there, having not enough space)
Burning Brakes
Joined: Jul 2009
Posts: 1,240
Likes: 294
From: ESCONDIDO CA
2025 C2 of the Year ('63 and '67) Finalist - Unmodified
C2 of Year Finalist (appearance mods) 2019
Here's a little different take. If it's been mentioned, sorry for the duplication.
I've had some success by backing off (retarding) my initial timing just a bit; then connecting my vacuum advance (at distributor) to full manifold vacuum, not ported vacuum.
I've had some success by backing off (retarding) my initial timing just a bit; then connecting my vacuum advance (at distributor) to full manifold vacuum, not ported vacuum.
Pro
Joined: May 2011
Posts: 722
Likes: 58
From: Karlsruhe (Germany)
Made a testdrive this evening (colder temps), and it run without problems. Measured the carb temp and it was around 52°C, - 10°C lower than the boiling level.
In Germany we have the choice between 10%, 5% ethanol in the medium fuel, and 0% in the premium fuel with higher octane. I use only the premium.
The normal fuel has only 91oct. in US measurement and my engine is made for 92. So I have to drive it on 95oct MOZ, thats 98oct ROZ in Europe. But thats not the root cause of the problem. I will put in a heat shield and hope all problems are solved ;-)
In Germany we have the choice between 10%, 5% ethanol in the medium fuel, and 0% in the premium fuel with higher octane. I use only the premium.
The normal fuel has only 91oct. in US measurement and my engine is made for 92. So I have to drive it on 95oct MOZ, thats 98oct ROZ in Europe. But thats not the root cause of the problem. I will put in a heat shield and hope all problems are solved ;-)
