1982 Oldsmobile 98 Lean Backfire

1982 OLDSMOBILE
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JAMES1982
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  • 1 POST
I have a 1982 oldsmobile 98. I keep hearing that the vehicle has valve problems but with no leak I don't believe it. I have problems when I accelerate that I didn't until someone looked at the vacuum line configuration. I'm wondering what to look at because the car seems to backfire and have a tough time accelerating as though fuel is not reaching the carb fast enough.
Apr 16, 2006 at 2:04 AM
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LOSONE
  • ✓Experienced Mechanic
  • 1,616 POSTS
If the oil fill pipe for the engine is in the front and not on the valve cover you have a 307 olds engine. It is one of the best engines made with rollar rockers and a bullet proof bottom end.

I doubt that you have a valve problem but you have a carburator problem. The back fire is from a lean mixture from the feedback carb. It takes an "old hand" mechanic like me to be able to repair it as the carb is computer controlled. I suggest you get someone with a scanner who can check the system. You are looking for a dwell of 30 degrees on the carb. You also need to be in computer "open loop" for eveything to work right.

To some it is a complicated but it shouldn't be too hard to fix if you have a tech that knows that old Rochester Quadra Jet feed back system.. Good Luck
Apr 16, 2006 at 2:15 AM
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Suggested Repair

Have a technician familiar with the computer-controlled Rochester Quadrajet feedback carburetor scan the system. Confirm about 30 degrees carb dwell and that the computer is in open loop. The backfire and poor acceleration are attributed to a lean mixture from the feedback carb, not a valve problem.

Conversation Summary

The owner of a 1982 Oldsmobile 98 reports backfiring and hard acceleration after someone changed the vacuum-line configuration, and doubts reported valve problems because there is no leak. The expert says a front oil-fill pipe would indicate a 307 engine, doubts a valve issue, and attributes the lean backfire to the computer-controlled feedback carburetor. A scanner-equipped technician who knows the Rochester Quadrajet feedback system should check for about 30 degrees dwell and open-loop operation.

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