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Author Topic: exhaust smell  (Read 2023 times)

Offline canadian nascar

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exhaust smell
« on: August 25, 2018, 02:47:09 PM »
hi,
I have a 301 turbo pontiac, it has a 262 comp cam ,raised compression. I tune by a/f gauge and vacuum gauge.

My problem is my clothes always stink of exhaust after driving in town windows down,

full exhaust no leaks. I have a choke issue that it will always have to be kicked down to idle after driving in summer weather, the electric choke mech is turned clockwise lots, I believe all the way clockwise at the moment to stop high idle, it want to rise 3-400 rpm off of idle which is 6-700rpm in drive, kick it and it comes off but always comes back.

The carb does leak out the bowl as it always has to be refilled after sitting a day or two, I know a couple plugs are supposed to be marine epoxied.

A/f is 15.5 at idle sometimes a little leaner, cruise is 14-1

I did Cliff's recipe 2 to the carb, stock primary rods and 71 jets.

any help would be appreciated Kevin

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301t,  8.5-1 comp, 262 comp cam, kb lw forged pistons, balanced crank, meth injection, 1.65 valves, roller rockers, 2.5'' dp, turbo exhaust wheel clipped 10degrees,   16lbs boost. dynoed 290whp, better tune scored est. 50hp more.

Offline Cliff Ruggles

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Re: exhaust smell
« Reply #1 on: August 26, 2018, 07:56:12 AM »
Simply a poor cam choice for the little 301 turbo engine.  For boosted engines we want to reduce overlap as it is not needed to scavenge the cylinders and improve cylinder filling.

The 262XE cam is too much cam for the little 301 even N/A versions, so you are going to get a considerable amount of unburned fuel dragged over into the exhaust stream right to start with.  This will result in low vacuum at idle, stinky exhaust, etc.

Timing at idle and fuel added will help, but the real cure is to go to a cam better suited for the engine.....IMHO.......Cliff
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Offline 77cruiser

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Re: exhaust smell
« Reply #2 on: August 26, 2018, 08:15:54 AM »
Is the idle set for best vac. or did you set it to AFR? Set it to best idle/ vac. & see if it helps.
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Jim

Offline Cliff Ruggles

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Re: exhaust smell
« Reply #3 on: August 26, 2018, 04:03:27 PM »
I've had a handful of 400 Pontiac engines brought in here for custom tuning using that cam, none of them idled well or were the least bit impressive anyplace for power production either.

I can't imagine that cam in a 301 CID engine with stock compression, turbo or otherwise.......Cliff
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Offline canadian nascar

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Re: exhaust smell
« Reply #4 on: August 27, 2018, 05:09:04 AM »
hey Guys,

Thanks for the replies, I have done both tune with vacuum gauge and a/f gauge, I am at best I believe right now, vacuum would be -13 14 in park.

Cliff where would I find a good cam for my application?

Kevin
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301t,  8.5-1 comp, 262 comp cam, kb lw forged pistons, balanced crank, meth injection, 1.65 valves, roller rockers, 2.5'' dp, turbo exhaust wheel clipped 10degrees,   16lbs boost. dynoed 290whp, better tune scored est. 50hp more.

Offline Cliff Ruggles

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Re: exhaust smell
« Reply #5 on: August 28, 2018, 05:35:36 AM »
Use the link below and contact these folks, they specialize in Pontiac 301 turbo applications:


http://www.ttaperformance.com/
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