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Discussion Starter · #1 ·
I'm a complete novice when it comes to engine work. I replaced a 4 barrel Rochester Quadrajet carb this weekend in my 72 Chevelle (Malibu) with a newer version of the exact same carb. Now, the car starts- but only for about twenty seconds with me giving it gas. Once the idle drops back down, that's it.

The float went bad in the old one, so I unbolted it, unhooked all the hoses, laid a rag over the manifold ports, and pretty much did it line for line like all the online instructions said to do. I used a good bead of seal all the way around the gasket, etc. When it came time to bold it back on, one of the bolts from the old one wouldn't fit in the new one. I didn't have new bolts, so I just bolted three of the four bolts down real good, and ran to Autozone to get another bolt. The whole process took about an hour. I'm wondering if the seal may be causing that. Even though this carb had 3 good bolts holding it down until I got the 4th one in. Beyond that, I have no clue what could be causing it. Any ideas?
 

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3 out of 4 won't cut it. the base will warp a bit causing a vacuum leak. this is also why the bolts are suppose to be done in a criss cross fashion when tightened. sealer is not needed and will most likely cause a vacuum leak also, just a new gasket.
 

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Sealer may have plugged up passages in the bottom of the carb.

I also agree that you could have warped the base with only three bolts and caused a vacuum leak.
 

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Discussion Starter · #6 ·
If I take my foot off the gas, it will cut off immediately. If I keep giving it gas, it will run for about 30 seconds more, and then cut off- with me giving it gas. Would two year old gas in the tank cause this problem?
 
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