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checked out a modded thirdgen, I have questions

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Old 04-24-2008, 03:08 PM
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Car: 1988 Pontiac Trans Am
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checked out a modded thirdgen, I have questions

Ok. The girlfriend and I went and checked out a TransAm with a 350 and 5 speed. I figured this was a weird combo seeing how the 350 and 5 speed were never options offered together so I had to go see. We get there and I check the VIN and sure enough this thing was an LG4 before. Guy was running it with the stock LG4's carb on this 350 H.O. from GM Performance. Question I have is ... will the stock carb from a 305 LG4 be enough to supply enough fuel and air to this engine, or will the engine lean out.
Old 04-24-2008, 03:32 PM
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Car: 84' Z28-White/T-Tops
Engine: H code LG4 305
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Axle/Gears: Stock 3.23
Re: checked out a modded thirdgen, I have questions

It's a perfectly fine carb for the 350 but the secondary's rods may need changed to fine tune it.
Old 04-24-2008, 04:29 PM
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The engine won't "lean out", but some stock LG4 q-jets had the secondary air valve travel limited. Check out this tech article linked from the thirdgen.org homepage https://www.thirdgen.org/quadrajet

I know the article says "computer controlled q-jet", but the AV mod applies to either CC or non-CC. since you're in Canada, I'm assuming this is a non-CC q-jet.
Old 04-24-2008, 09:33 PM
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Car: 1988 Pontiac Trans Am
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Re: checked out a modded thirdgen, I have questions

ok...I was wondering if that carb would lean it out cuz periodically the car will blow a puff of blue smoke...

dude wants 3000 for the car. Body is in ok shape but that 5 speed 350 setup kinda worries me...I offered him a low ball 2000 to see if he would bite...he is pondering it.
Old 04-24-2008, 10:59 PM
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Blue smoke is oil. I'm guessing you saw it during/after a shift. You'll probably see it if you restart it 5-30 minutes after turning it off hot.

Valve stem seals. Common SBC problem, relatively simple fix.
Old 04-25-2008, 04:22 PM
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Re: checked out a modded thirdgen, I have questions

actually we saw it durring idle
Old 04-26-2008, 06:21 PM
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Re: checked out a modded thirdgen, I have questions

Just make sure it isn't actually a 350 that came from a J/Y.
Old 04-26-2008, 06:25 PM
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Re: checked out a modded thirdgen, I have questions

make sure it actually is a 350... to start then worry if it came from a junkyard
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