1967 327 300 automatic eratic idle cold or hot

[Lou A.]

this has been an on going problem since i had car sometimes its ok and then not, new driviline suggests plugging manifold holes under car //// with what. all is new carb, tuneup, pcv, vacumn hoses sometimes idles at 600 in drive cold after when hot goes to 500 rpm and sounds like ignition is retarded HELP thanks guys.

[William C.]

Re: 1967 327 300 automatic eratic idle cold or hot

600 cold is pretty slow, but for your hot problem, I'd start by looking at the vacuum advance can. It should be full in at whatever vacuum you have available with hot engine in drive with the vacuum advance disconnected. A mismatched vacuum can="retarded" timing at idle.

[Duke W.]

Re: 1967 327 300 automatic eratic idle cold or hot

I can't make any sense out of most of your post, but like Bill said, check the VAC. If original, it should be a "355", and the specs are in your CSM and AMA specs. The correct current replacement is B20 or B26. Also check the rest of the spark advance map.

The normal hot idle speed for your engine is 500 in Drive, and it should be smooth and stable with somewhere in the range of 20-26 deg. total idle timing and it, too, should be stable at idle speed.

Take vacuum readings idling at 500 in Drive and 500 in Neutral, and tell us what they are and whether or not they are steady.

Duke

[Bob R.]

Re: 1967 327 300 automatic eratic idle cold or hot

Chevrolet calls for an idle speed of 500 rpm in drive for your car. Those are the factory specs as noted in the responses above. If your engine is not completely stock the idel speed could be different. My 327 / 300 hp engine has a more aggressive cam then stock and it idles very nicely at 700 rpm but will not idle smooth at 500.