Vintage & Classic Cadillacs 1902-1977 Cadillac Models

rough idle and chugging at low speeds

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Old 10-07-2008, 09:19 AM
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Default rough idle and chugging at low speeds

been driving my 71 eldo all summer, running great. last few weeks have been a little rough at idle and at low speeds. car runs great at 40 - 70 mph. is this simply a tune up? fuel issue ? any thoughts?
 
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Old 10-07-2008, 11:32 AM
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Default RE: rough idle and chugging at low speeds

Can you adjust a Quadrajet? That might help. Carb cleaner too. Fuel filter check. I see you are in NY, weather is chilly nowcould be choke adjustment as well. A tune up would get it running better. Spark plugs and wires points condensor timimng set up.

If you want instructions on carb and choke set up take a few pics front and both sides and post here and I can tell you what to do, it's not that hard.
 
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Old 10-07-2008, 11:57 AM
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Default RE: rough idle and chugging at low speeds

Thanks again for your input. I will leave the tune up to a professional. while we are at it, any fuel recomendations? i purchase 93 oct. , highest available here, should i put in an additive? and suggestions?
 
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Old 10-07-2008, 01:00 PM
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Default RE: rough idle and chugging at low speeds

In 1971 the 500 CID V8 had the compression ratio dropped to 8.5:1 instead of the previous 10:1. This means that you can safely run the 93 Octane. If it runs well and has no knock you should be fine. I think 91 would be the minimum you should go.

Also Pre-1971 engines were equipped with "soft" valve seats and leaded gasoline acted as a lubricant to prevent excessive wear of the valve seats. Using these engines with unleaded fuel in high-speed/high-load situations could result in some valve seat wear. (Boats, some farm equipment, and tow vehicles may be included in this category.) Since you have a 1971 motor there is no need to use substitute lubricant additives.

Choose your mechanic carefully, there is a newly certified Honda factory trained Class A mechanic in my nieghbour's family and he was never taught how to work on a carburetor.
 
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Old 10-07-2008, 02:18 PM
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Default RE: rough idle and chugging at low speeds

I am fortunate enough that in the small town where i have a home, the local mechanic grew up on engines like mine. he knows them inside and out and doesnt mind re-living old memories while working on my engine.
 
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Old 11-05-2008, 07:06 PM
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Default RE: rough idle and chugging at low speeds

new points, plugs , etc etc. car is running like it is 1971 again. going to get the carb rebuilt by an outfit in nj, been in business for 60 years. the car is running great , hate that it is winter
 
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Old 11-06-2008, 06:50 PM
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Default RE: rough idle and chugging at low speeds

Glad to hear the car is running much better. Good idea on your carb too. Perfect day here in Toronto , keep driving until the snow flys!
 
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Old 11-09-2008, 09:26 PM
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Default RE: rough idle and chugging at low speeds

50 and sunny today , took it out of storage for a few hours. great day
 

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