Exhaust Smell...Can't Breath - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 16 (permalink) Old Jul 12th, 03, 02:47 AM Thread Starter
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I bought a 69 Camaro with a rebuilt 350, Holley 750, headers and Comp 9000 HEI dist. The car runs excellent but the fumes from the exhaust are terrible (no smoke from exhaust). People (non-mechanical types like me) always say I am running "rich". I went to a speed shop and he had me put smaller jets in my carb. I set up the carb by the book, pulling max vacum. Also changed plug gap to .045 due to the HEI. Is this just the way old cars smell????

1969, 350 "Beast", M20, Nothing Fancy, Nothing Pretty, But Sure is Fun!

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post #2 of 16 (permalink) Old Jul 12th, 03, 03:23 PM
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Had that problem at one time, alot better now though.750's on a smallblock tend to "run rich" due to the idle circut being uncovered too much. No jet change will fix that, its an air bleed problem < being too small >.

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post #3 of 16 (permalink) Old Jul 12th, 03, 03:35 PM Thread Starter
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How did you fix the problem? I do not know a lot about these sort of things. I have an Edelbrock 600 I can put on...was told I would get more torgue with it.

1969, 350 "Beast", M20, Nothing Fancy, Nothing Pretty, But Sure is Fun!

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post #4 of 16 (permalink) Old Jul 12th, 03, 05:26 PM
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Are you complaining about exhaust fumes or a gas smell?

...Dennis

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post #5 of 16 (permalink) Old Jul 12th, 03, 05:51 PM Thread Starter
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It is the exhaust smell, not a gas smell. It is the kind of car that you would hate to be behind driving down the road because of the smell.

1969, 350 "Beast", M20, Nothing Fancy, Nothing Pretty, But Sure is Fun!

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post #6 of 16 (permalink) Old Jul 13th, 03, 01:35 PM
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I opened up the air bleeds some, adjusted mixing screws,and basicly redone the carb... still have some other issues with it... looking at a new carb. but haven't decided.

68 Camaro~LSx ~all motor
1.54 60'--6.95 @ 98.45 660'--10.96 @ 121.53
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post #7 of 16 (permalink) Old Jul 13th, 03, 03:09 PM
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Are you exiting the exhaust to the very back of the car or underneith the vehicle?? You might consider a Flowmaster Tailpipe system from summit for $99 that will reroute your exhaust to the very back of the vehicle. This will prevent the 'exhaust fume smell'

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post #8 of 16 (permalink) Old Jul 13th, 03, 03:13 PM
 
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What is your idle speed? How much vac. are you pulling at idle?
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post #9 of 16 (permalink) Old Jul 14th, 03, 01:40 PM Thread Starter
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My exhaust does run the length of the car and out the back. It has been quit a while since I set the carb up (years) and I know this doesn't help much but a mechanic friend was there and was "impressed" with how much vacum I was pulling because the car has an aftermarket cam in it. I do not remember how many inches it was pulling. My idle is about 700 -800 rpm's. The other thing I forgot to mention is my plugs are always black. I put a new set in last week, just pulled one and it is black and smells like gas?

Do you guys think the Edelbrock 600 would be the way to go instead?
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post #10 of 16 (permalink) Old Jul 14th, 03, 03:29 PM
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Black plugs are fouling because you are running rich ( unless they are oily black ). Going to the edlbrock will almost certainly clean up your plugs. However, you will lose some of the get up and go that you now see with the Holley. Still, it may be awhile before you can rid yourself of the smell because that smell is now throughout the exhaust system and will not immeiately go away.
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post #11 of 16 (permalink) Old Jul 15th, 03, 09:56 PM
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try turning idle mix screws in about 1/8 turn from max vaccum.if it doesn't stumble slightly at freeway cruising speed keep going 1/16th turn at a time until you notice the stumble,then back out until it just goes away plus 1/16th turn.this should clean things up about as well as you can get without drilling the idle air passages.
let us know if this helps
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post #12 of 16 (permalink) Old Jul 16th, 03, 06:22 AM
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I know you jetted down but how much? Lets break things down and rule out what we can.

If you smell exhaust in the cab of the vehicle, I'd suspect an exhaust leak under the car. If I were following you would I smell it too? Black plugs make me think so and indicate a rich condition. Just cruising you'll be on the primary side of the carb most so I'd look at the jetting there.

Do you only smell it when stopped and the engine is running? That would indicate a rich idle condition. Check your idle mixture screws and lean the idle out some.

The thing that came to mind when you said;
Quote:
It is the exhaust smell, not a gas smell. It is the kind of car that you would hate to be behind driving down the road because of the smell.
is bad gas. You set the carb up years ago, how much use has it seen?

My last thought is what plugs are you running? You could be fouling plugs by running a plug that is too hot. This would effect combustion and creat an inefficent condition where all the fuel isn't being burned...

...Dennis

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post #13 of 16 (permalink) Old Jul 17th, 03, 04:09 PM Thread Starter
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I thought the idle mixture screws for just the idle and had no effect while driving but I'll give it a shot.
The car smells at idle and while driving down the road. My wife followed me one time and said it smelled bad.
As for spark plugs, I use what ever the part store says (the ones the catalogs say are for a 1969 350). I have tried different brands. One thing I did do this time was increase the gap by .010 because I have the electronic ignition. That was something I read on several sites so figured I'd try it, runs great.
I do not remember the jet size, think it was either a 69 or 71.
I know the gas is good because I pulled the tank and drained the old gas out plus cleaned the carb.
I was going to put the 600 on but I don't want to lose the power, after all that's why we drive these.
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post #14 of 16 (permalink) Old Jul 19th, 03, 03:15 AM
 
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Hey guys, don`t forget about the power valve.At idle, jet size isn`t a concern cause your in the idle circiut.But the power valve will enrichen the mix when open regardless of throttle angle.If it`s been sitting a while,they can dry out and split open,dumping fuel full time. Don`t forget to change the oil too, as all that unburned fuel you found on your plugs didn`t stop there.When the crankcase gets dilluted,you would not know if the carb was in correct tune or not, due to it burning unmetered fuel from the crankcase through the pcv system. Just a thought.
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post #15 of 16 (permalink) Old Jul 19th, 03, 07:44 AM
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Had the same problem with a holley 650. Inside there is diaphram that controlls the flow of fuel. If the car back-fires it will rupture this part and the engine will begin to free-flow fuel. No amount of adjustment will help you if this is the case.

I changed to an Edelbrock and fixed the problem.
GOOD LUCK!
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