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I purchased this 1988 Cad Brougham with the 307 engine from the original owners, an elderly couple. They gave me all the maintenance records for the car. In its lifetime, it has had a couple coolant and ATF flushes, a tuneup, consisting of new spark plugs, and a new water pump and belts. It now has 52,000 miles on it. Except for a few leaks (which I am now addressing), it is in nice shape inside and out, and it runs very good.

Q : The carb has never been touched, but the driveability is very good. The bores and throttle plates, etc. look clean. Should I follow the old "If it ain't broke, don't fix it.." rule and leave the carb alone, or while I have it off replacing the intake manifold, is there anything that I should do, while I have accessibility ? The same question would apply to the fuel pump and the radiator. These parts are now 17 years old, but still doing their job well. Should I reasonably expect that they will continue to do so ?

Any comments are much appreciated.
 

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70 Fleetwood, 87 and 90 Brougham, 94 Fleetwood
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If it is running good and getting decent fuel economy, leave the carb alone. These 3C carbs can be fussy, not like the good old simple Q-Jets we have come to love.

About the only thing I would do is remove the lid and check the float level. This one thing can make a differance in fuel economy and emissions.

Mike
 

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94 Fleetwood Brougham
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Heck, while you are in there checking float, just replace it. Nitryl floats are better, brass ones often develop leaks long term.

I have had good luck reusing gaskets that haven't torn, just don't overtorque the bolts, 10 ft/lbs. Mine got damaged by a gorilla mechanic, so becareful.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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Don't touch the carb, just gently remove it and set it on the bench! don't turn it over either, allows sediment to circulate through the carb. I would never remove the top unless theres a reason. While its on the bench, replace the small fuel filter located behind the large nut at the fuel inlet. Be careful! use two wrenches of the proper size to remove it it is easily damaged. Would not hurt to have the radiator flow tested while out because you are repairing a lack of timely maintanence of the cooling system which caused the intake gasket failure.
 

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At that mileage, my bet is the carb is just fine. As for the float level, unless you are well versed with that carb, I'd advise to NOT open it just to check the float level. It's quite easy to check "externally", and quite easy to cause a problem internally in the carb.
 

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94 ETC,97 STS
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I'd go with the not broke rule. If it ever acts up do an overhaul. Otherwise just carefully set it aside.

I'd change the coolant & check the hoses but othewise I'd leave the rad alone.
 

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I wholeheartedly agree, if it s running good, leave it alone. 90% of Q-Jet woes are from people tweaking and adjusting when they think they know more than the engineers who designed it. It was intended to be hands off for nearly all its life. Following the GM book of knowledge, occaisional cleaning is all that is needed.

I can't tell you how many times I have found carbs all screwed up, and just taking the time to get back to stock GM, it runs like EFI. My 1985 Cutlass with the E4MC on it would rival EFI for starting, in any weather. And I NEVER had to pump it to start it. just a light tap of the gas pedal to allow the choke to set, and crank.

I did my mods (seen elsewhere on this site, I think in the tech forum) ALL worked WELL with the factory GM computer and overall enhanced drivability of my car. Note, MY car, not for everyone's car. I had a 350 in place of the 307 (both Olds) and a mild cam (which was wrong for the lack of compression it had, 204/214, from SSI).

Just clean it up with Gumout. I like Gumout, as it isn't too harsh to strip the carb of all its (gold irridite?) plating, yet does well. Walmart brand is hell on the plating, avoid!! But very strong. Good clean AC Delco air filters, and factory settings if needed.

Common issues with the Q-Jet are the primary vacuum break (aka, Choke Pulloff) will start to leak and will cause cold start to start, then stall, then restart ok symptoms. But overall is generally ok to drive.
 

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I have a neighbor who "knows it all", he changes his engines more than I change my oil!! He doesn't believe in all the "fuel injection crap". We live in WI, and he doesn't even believe in a choke! He pumps the crap out of it and cranks and it sputters and bucks and he revving the pee out of it to keep it running. I have offered to help, but nope, he doesn't want that crap... ok.... fine with me! (It is a 77-78 1ton truck made from a 3/4t, now with ambulance 4.56's, duallys, had a 300 I6, then another, then another (I think this one was the original 300 "fixed"), then a 302, then another (backyard rebuilt, rings bearings, etc), then a 351M, and now another... That is in around 2.5 years.... The current engine has a big 222-228 duration cam in it, it sucks till he revs it up. He can't even tow big loads now unless he is down a gear from the last 351... Big cams aren't worth it in heavy stuff!)

So, enough rambling. Like Kat and zonie said, if good, leave alone. If it is an unmolested Q-Jet it will run great for many many years. Mine went untouched for nearly 200K miles. The only reason I messed with it was I found the bolt bolting the front drivers side carb cranked down and it crushed the body and TPS was off and could no longer be adjusted. I HAD to fix. Took another carb and go through that one. Most people get in and mess with things to bandaid a problem that they refuse to do right or don't know how to do right and often make it worse.
 

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The Quadrajet can be tested and adjusted using a GM manual, simple tools and a DVM. Of course there are other things to consider such as sensors when diagnosing a problem. If there aren't any problems, like the previous people said, let it be.
 
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