# Carburetor leak down



## RT-1 (Mar 21, 2012)

Hi everyone. I've almost completely restored my grandfather's 65 Tempest. Everything has gone smoothly save this one frustration.

I have rebuilt the carb- it runs beautifully, however if I don't drive it within a week, the carb is dry. I can't locate the source of the leak. Any ideas? Thanks.


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## RT-1 (Mar 21, 2012)

I should add- its the stock Rochester 2 barrel on a 326


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## geeteeohguy (Feb 2, 2008)

On the 2bbl carb, bowl leakage is not the norm. My bet is that the newer, highly volatile gasoline is simply evaporating. 3 solutions: drive it more often; install an electric fuel pump to prime it; or simply crank it over in 15 second intervals with a rest period in between to let the starter cool until it cranks up. It shouldn't take long for fuel to get to the carb, and you'll always have oil pressure on the cold start...not a bad thing.


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## lars (Sep 28, 2004)

Although your Rochester 2-Jet is significantly different from a Q-Jet, my Q-Jet Tuning paper has a complete section on fuel bleed-down/hard start issues that apply to your 2-barrel in many cases - it also addresses the issue outlined by geeteeohguy above. Simply e-mail me for a copy of the paper and check out the last section of the paper on this issue.

Lars
[email protected]


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## RT-1 (Mar 21, 2012)

I've been fighting this for a couple of years. I did put an inline electric fuel pump which does overcome the issue. I was worried if fuel was leaking internally, I'd be draining several ounces into the cylinders which would cause fuel dilution of the oil. I've read about the higher evaporation rates of newer fuels, but I don't have this problem on my 57 Chevy. 

On a side note - why on earth in this era of emission requirements would they make formulations that evaporate more rapidly than the old blends???


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## lars (Sep 28, 2004)

RT-1 said:


> Why on earth in this era of emission requirements would they make formulations that evaporate more rapidly than the old blends???


Do you honestly believe that your elected political (left wing) officials are technical engineering experts on the issues of emissions...? Repeat after me, "Corn Grower's Lobbyists," "Alternative Fuels."

If you really think these people have "emissions" in mind, please sell me your Tempest for $500. This is about making money.

Lars


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## RT-1 (Mar 21, 2012)

Ok- I read Lars excellent article. I ordered a new power valve since that's the only thing on the bottom of the fuel bowl. I also ordered a fuel pump rebuild kit. Hopefully if I do all these things it will stop the leak down.


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## lars (Sep 28, 2004)

Not likely. The power valve cannot leak the fuel out of the bowl, and the 2GC carb has the needle/seat on the top of the carb, so fuel pump drainback is not an issue. You are suffering from the fuel issue discussed earlier, and the fuel is simply evaporating below the level of the accel pump supply slot. You either live with it, or start the engine more frequently. You can also use an electric pump as suggested above. Verify that your accel pump is, in fact, operating and functional (strong solid squirt when the carb bowl is full). If it is, you have little recourse on this issue.

There is a remote possibility that you could have a cracked or porous carb casting. To verify, you can pull the carb, fill the bowl, and set the carb up on your workbench on top of some tall sockets at the throttle plate bolt holes: Observe the bottom of the carb for leaks or drips. If nothing is dripping out the bottom, your only problem is the evaporation issue.

Lars


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## jmt455 (Mar 26, 2012)

Are you using the inline (paper) fuel filter in the carb inlet? That filter has a check valve built into its inlet end. If it's not there or it is damaged, fuel could (possibly) be draining back out of the carb after the pump pressure drops.


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## allpawl66 (May 9, 2008)

When done driving , manually close the choke flap as it will slow the evaporation of the alcohol based fuel .


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## RT-1 (Mar 21, 2012)

I pulled it apart again today. I tried the short filter, but it doesn't fit in my housing. It's a good 1/4" longer than the brass filter. Plus, like Lars pointed out, the 2G fills from the top. No well plugs either. I'll try the choke trick. I want to keep it 100% stock so I'll pass on the electric pump for now. Thanks for all the ideas.


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