Engine wants to kill when spraying carb cleaner around Intake? - Chevelle Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 11 (permalink) Old Nov 18th, 19, 2:39 PM Thread Starter
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Engine wants to kill when spraying carb cleaner around Intake?

Having issues with idle. Today decided to spray carb cleaner around the intake where it meets the heads and block. Car started to kill/stop, I thought it was suppose to speed up. Did I spray too much? Or does this indicated a leak. Old Performer intake installed on a 350 with 305 heads about 20 years ago. Any opinions? thanks


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post #2 of 11 (permalink) Old Nov 18th, 19, 3:09 PM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

First thing I would do is check the torque on the intake bolts. If that doesn't improve anything I'd definitely get a fresh set of gaskets in there.

Good luck!
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post #3 of 11 (permalink) Old Nov 18th, 19, 3:24 PM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

Like Jeff said tighten intake bolts. A way to check for vacuum leak, when you do this you might even hear the vacuum leak. When the car is running at idle put your hands over carburetor, by doing this your taking away air. If you have a vacuum leak the engine will keep running. If it wants to stall, then no leak.
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post #4 of 11 (permalink) Old Nov 18th, 19, 6:06 PM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

Please be aware, there used to be about 2 billion different sizes of small block intake manifold gaskets, from the smallest ports, all the way to foot long by foot long. It might be needed to actually pull the manifold off to see what gaskets will fit both the head ports and manifold ports.

I used to see good combinations of head and manifold mismatches that would have worked with one of the gasket sets, but, not the ones they used. There are more parts, gaskets and stuff built for the small block Chevy than any other engine in history, can make for some very dubious combinations at best. Common sense and research should do wonders to get stuff that works together.
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post #5 of 11 (permalink) Old Nov 18th, 19, 9:55 PM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

Yes, I do believe it indicates a vacuum leak and the idea here is that the RPM changes in some way . . . and yours did. Try the same test at the same places on your engine using an unlit propane torch but with a good amount of propane flowing. This should also cause a change in RPM and might help you narrow down the location of the vacuum leak.

Rick
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post #6 of 11 (permalink) Old Nov 19th, 19, 8:18 AM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

Sounds like you have a large vacuum leak for sure,you can also use an old pump style oil can and go along the intake and see where it changes the RPM,and if retorquing the bolts don't work you can look for the problem @ that spot when you remove the intake.
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post #7 of 11 (permalink) Old Nov 19th, 19, 8:53 AM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

One of these days your going to catch a leaking spark plug wire or get too close to the distributor cap with that spray and poof, its going to light up in your face.. It happened to me many years ago using Gumout spray..
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post #8 of 11 (permalink) Old Nov 19th, 19, 9:05 AM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

Quote:
Originally Posted by hydro462 View Post
One of these days your going to catch a leaking spark plug wire or get too close to the distributor cap with that spray and poof, its going to light up in your face.. It happened to me many years ago using Gumout spray..
Well damn, good morning to you too sunshine.

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post #9 of 11 (permalink) Old Nov 19th, 19, 5:18 PM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

I have been using unlit propane for decades now, never a flame up. I also use a DC fan to blow air over the areas I am not adding the propane to, fan keeps the vapors away from the distributor when aimed correctly.

And, you didn't check the wires for leaks before going on to the unlit propane, or other chemical vacuum leak checks, wrong procedure.

Here's something else, I also use unlit propane as a method to test the carb, right down the carb enry. Speeds up, too lean, stops down, too rich.

I am a dare-devil. It's fun.
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post #10 of 11 (permalink) Old Nov 19th, 19, 5:25 PM Thread Starter
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Re: Engine wants to kill when spraying carb cleaner around Intake?

This is all new to me Dave, so I don't understand your second paragraph "And, you didn't......, wrong procedure.

The plug wires are new. Are you saying I should or should not check the wires for leaks? By this I assume you mean run the car in a dark garage and look for light around the plug wires?


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post #11 of 11 (permalink) Old Nov 20th, 19, 11:39 PM
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Re: Engine wants to kill when spraying carb cleaner around Intake?

I apologize, that wasn't aimed at the OP, but the person that suggested we don't test with any chemicals, from the possibility of bad wires and arcing, hydro462.

We all care about safety, and his post was timely and proper. We all need to be careful with our testing. Even a leak from the carb could have set a fire, or explosion off. He did a good call with it.
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