1970supremevert

Hello all ,

I am looking to pick up a 84 Supreme with a 307 , confirmed only 82k on car anything I should know about this power plant? problems etc
thanks in advance

joe_padavano

The most important thing you need to know is that it uses the computer controlled Qjet - the CCC system. When it's properly tuned, it works great, but there are about a million things that can cause it to screw up, primarily a leak in any one of the many miles of vacuum hose on the engine. If you are planning to have someone service the car for you, be aware that virtually no current mechanics know how to properly service it nor do they want to take the time. If you plan to work in it yourself, RUN, don't walk, to ebay and buy a factory service manual. Follow the servicing and adjustment process for the CCC system TO THE LETTER. It took me a month of weekends to finally figure this system out, but again, once everything is correct and properly tuned, it works great.

1970supremevert

thanks Joe, are you close to Tysons Corner??

joe_padavano

I work in Tysons, live in western Loudoun.

Red Delta

My 85 LeSabre with a 307 didn't use the CCC, my grandmother had an 85 LeSabre as well, hers didn't use the CCC either. My 88 Cutlass did, however.

Both cars were Canadian, is that the difference?

henryk8398

I believe Canadian cars got the CCC in 1986 or thereabouts.

joe_padavano

Yes. Emission control laws phased in later in Canada than in the US.

Did both cars happen to come with 6A heads?

OLD SKL 69

Joe pretty much summed it up with the CCC system. I have owned 2 of these 307's with this system and they are very reliable. If the vacuum hoses are original, I would replace them as they are probably dry rotted and could start leaking. These engines run smooth, get good gas mileage and are usually trouble free. Only downside is that they are not very powerful. Good hunting.

CRUZN 66

X2..... I have several 307's.... The only issue I have had are related to the MAP Sensor and the usual leaky valve covers (which is common for all the 5-Hole valve covers)....