Freebeer

I have a 1967 Cutlass with the 330 engine (I believe it is the low compression model) Should I add octane boost and or lead additive or can I just use regular unleaded?? Any suggestions would be appreciated. Thanks!

Tom

Fun71

Don't waste your money or time on the octane boost; just use whatever grade fuel your engine can run on without knocking (89, 91, etc). Mine runs on 91 most of the year but during the winter 87 works OK.

MDchanic

+1.

For a 9:1 motor, 89 or 91 should be fine (87 might be pushing it).

As has been discussed here (and on every other internet forum, including knitting.com), unless you are constantly towing or racing, you don't need a lead additive.

- Eric

oldcutlass

+2

Freebeer

Thanks for the reply's...I have a little "run on" from time to time when I turn off the engine and it seems to idle a little rough. Before I have the carb looked at I was told to try adding sea foam to clean the components and then try a little higher octain gas or additive. I think the car runs good down the road but to be honest, I am not sure what type of performance I should get out of it so I can't tell if it's running as good as it should or not. I don't get any pinging or knocking just a little rough idle and the run on....

Thanks

oldcutlass

Maybe a tuneup is order?

Fun71

I have had run-on issues a couple of times over the years due to high idle speed and too far advanced ignition timing. Both are easy to correct as part of a tune-up as oldcutlass suggested.

jaunty75

One short-term way to stop this is to shut off the engine while the car is still in gear, and then shift into Park. The added drag of trying to turn the transmission and drivetrain is usually enough to stop the engine.

MDchanic

I had a '68 Mercury Colony Park wagon once that would run-on so badly that if you shut it off in Drive and gave it a little gas, it would drive down the block.

When it's that bad, thee's a good chance that the problem is red-hot carbon deposits encouraging preigniton. I am under the impression that letting the cylinders soak in Marvel Mystery Oil will dissolve the carbon, but I have not tried this trick myself.
Obviously, if you fill your cylinders with liquid, you need to turn the engine over with the spark plugs out to avoid bending a rod.

- Eric

Freebeer

Thanks for all the replys...I ran some Sea Foam through it and then a higher octane gas. So far the car runs a lot smoother and the run on has stopped. Hope it lasts....

oldcutlass

With the chemical makeup of seafoam, it may be masking the symptoms of a poorly tuned engine and your problem will resurface in a few tanks of fuel. You may want to double check your tuneup settings. I always check mine twice a year, usually when the fuel goes from winter to summer blend and then again when it changes back.

Freebeer

Thanks..will do. So far so good, but the car is relatively new to me and I have not had the timing or plugs checked yet....just oil/filter. Funny thing is, I was driving around this afternoon and spotted a nice 67' 442 at the local ice cream shop...I had just commented recently to a friend that you don't see this model very much at shows..just the 68-72's mostly. I really love these cars......best value out there in my opinion.

oldcutlass

I also like the square "A" body cars. You right not many at car shows, usually just me. Then you have the people that come by and look but have no clue to what it is.