1987 Chevy Caprice carb service (150,000 miles).

Hi
Can anyone recommend the best way to tune a carburretor on a Caprice for better economy. To my knowlege, this hasn't been done in years.

 

Unless your carburetor has been changed there is no tune on it. It's all done by the ECM a very early OB1 system.

Welcome

 

carb tune

Thanks Cliff -

So, if I have this right, and if it's the original carb, then you wouldn't touch it? Even as, with age, things will wear out? I have a carb repair kit: are there any items that could be replaced as a good preventative measure?

 

Sorry, that's not correct. The CCC Qjet needs to be cleaned and rebuilt like any other carb. The process is spelled out in detail in the factory service manual. Get one before starting this process. Note that the CCC system uses miles of vacuum lines with various sensors and actuators. As these hoses age and leak, they cause the system to work poorly and mileage suffers. You MUST ensure that every inch of the vacuum hoses and every part of the CCC system is working properly. Once you've done that, the carb should be rebuilt and adjusted by following the procedure in the manual exactly. Most mechanics no longer know how to properly adjust the CCC system and fewer still have the patience to follow the procedure. It took me a month of weekends to fully understand my 86 and get it adjusted properly, but once done it ran great.

 

Joe - carb tune

Thanks too, Joe.

'Generally', what sort of mpg should one be getting after adjustment?

PHILIP

 

Yea listen to Joe he knows his stuff when it comes to this and many other things. The CCC system can be a pain. Any hose can make a difference. A carb rebuild can always help.

 

Mid to high teens is about the best you'll get.

 

Acvtually I have gotten over 20 with my wagon before I screwed around with it. The OD and 2.73 rear gear really help on the highway.

 

caprice carb Qs

Thank you very much again, Joe.

I've monitored this and on a motorway run I once got iro 24 mpg. Typically around town 12-15 mpg and, at other times, about 17 mpg. I was told that 15mpg is normal for the size/weight of car. In the UK, our lowest available gas octane rating is 95 (versus the 87 in the U.S), so driving on 'cream' is but one other thing to overcome...

My mechanic doesn't touch the carb.

Thanks for the advice.
PHILIP