Not running right - Team Camaro Tech
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post #1 of 9 (permalink) Old Apr 20th, 11, 09:03 PM Thread Starter
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Not running right

I’m having trouble figuring out why my 68 isn’t running right. It is a 350 mild GM crate (300 hp) with an edlebrock 1904 Q-jet type carb. When running it sounds like someone is clearing his throat –raspy sounding at the carb. It has about 17 steady on the vacuum gauge. The car has power brakes and air. Thinking that there might be a leak in the air vacuum system I plugged it at the manifold fitting—RPMS and vacuum drop and it runs even more rough. Any thoughts about where to start first?
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post #2 of 9 (permalink) Old Apr 20th, 11, 10:57 PM
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Re: Not running right

A smaal lph burner or ehgine start ( ether ) will locat a vac leak.....the $5 pencil lph burner is far less messy.....ether scews up polished Aluminium.

My Spelling is not incorrect...it is creative

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post #3 of 9 (permalink) Old Apr 20th, 11, 11:22 PM
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Re: Not running right

i think i would use break clean instead but--i am sure ur exhaust is clear --how about a change in timing--bad centrifical weights
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post #4 of 9 (permalink) Old Apr 21st, 11, 02:03 PM
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Re: Not running right

Quote:
i think i would use break clean instead
It just so happens that LPG is far safer than ccommonanly thought.

And the safe part is LPG has a very small ratio tolreance with air...unlike most other solvents....with the turbulance in the engine compartment diluting very quick
With a pencil torch the lpg is concentrated on a very small area and use a very small volume...IF in the very unlikely case there is an ign, its just a small flash....brake cleaner , engine start etc are fluids..they flash and the solvents laying around burn...

My Spelling is not incorrect...it is creative

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post #5 of 9 (permalink) Old Apr 21st, 11, 03:59 PM
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Re: Not running right

are you sure it just inst bad gas????????
btw I use a unlit propane torch to track down vacum leaks.
good indication of a vacum leak is a real fast idle


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post #6 of 9 (permalink) Old Apr 21st, 11, 06:16 PM Thread Starter
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Re: Not running right

In response:

The timing is right and han't changed. The distributor is relatively new and was working well. It could be bad gas but it would have had to be a couple of tanks full since it has been ongoing. The idle is a bit rough but not fast and really hasn't changed for over a year or so.

You all seem to think it is a vacuum leak and that is what I thought too. I did the carb cleaner process focusing on the intake manifold but the engine didn't speed up. Why do you think the engine rpms and vacuum dropped when I plugged the vacuum line to the air conditioning switches?

Thanks for your thoughts.
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post #7 of 9 (permalink) Old Apr 21st, 11, 10:07 PM
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darrell
 
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Re: Not running right

you dont have a egr valve style intake on this one--just guessing right now-valves adj a 1/4 turn too tight
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post #8 of 9 (permalink) Old Apr 21st, 11, 11:36 PM
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Re: Not running right

u have done nothing, changed nothing that may cause this...
There is an old saying....
"the is many a carb tuned by changing spark plugs"
And anyone who has been around engines for decades will know this...
change the plugs...clean the rotor and cap pins, check HT lead clips and boots, and check for HT leaks on a dark night.

My Spelling is not incorrect...it is creative

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post #9 of 9 (permalink) Old Apr 22nd, 11, 03:53 PM
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Re: Not running right

Hmmm, but if that is the case Steps, why did the plugs foul in the first place? Without correcting that, the plugs will foul again, but good idea to at least pull them and read them. It will tell you how the combustion chamber is burning.

alan
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