Sputtering Six

[65fast]

Whenever I shut my six down a a long/hard drive it coughs a few times, sputters and then finally stops running. However, if a let it idle for a minute or two before shutting it down the problem never seems to occur. Any suggestions?

 

[Asa]

carb running too rich?

 

[Anonymous]

timing too far retarded/advanced? dont know how much a rich choke will effect it since i have had mine up to 4 notches on the rich side before...i had it backwards...now its 4 notches on the lean side lol...also i have my idle speed screw way far out now...seems to run best that way...but check that...adjust the screw to where u get the highest rpm or smoothest idle...i dont know...but it does sound like it could be a timing issue..

 

[Anonymous]

That sounds like dieseling. I had that problem on my car and it turned out to be from carbon build up. If I ran my car for awhile and shut it off it would run on for a second or two then sputter and die. I always let the car idle for a minute or so before shutting it off or shut the car off in drive to avoid it. Then later on I put some of that fuel additive cleaner stuff in my gas tank and never had that problem since.
It could also be a timing issue, idle set too high or carb running too rich.

 

[Anonymous]

Go one step colder on the sparkplugs. I recently discovered that the local Auto Zoo and Checkmate computers default to the 1980 heat range for these engines, which is one step hotter than the original plugs. This will cause some exhaust valve heating, which cools down after a few minutes of idling, creating the very symptoms you are describing. If you do a LOT of highway driving, the hotter plugs will eventually cause burned exhaust valves.

 

[65fast]

I have checked the timing and its ok, I will mess around with the fuel mixture and plugs too to see what happens. Thanks for the help.

 

[Anonymous]

I had the same experience with my truck. Turned out that cooler plugs and a good carburetor tune-up stopped the problem. The engine was running too fat. Combine that with hot plugs and dieseling is bound to happen.


-Chris

 

[65fast]

How do I go about getting the colder range plugs. Is there a certain make/model of car I should try to get them from or just say I want so and so heat range. Also what type of range should I be looking at, I got some autolite's from Advance in their now.

 

[Anonymous]

I am not positive but I think that when people talk about heat range of spark plugs they are really talking about how the plugs are gapped. A longer gap is a cooler plug and a shorter gap is a hotter plug. You can re-gap your own plugs a little longer to cool them down, maybe 0.005".

-Dan in Atlanta

 

[ludwig]

You need to get to member CZLN6. He can give you the poop about colder plugs and gaps. Gap is not plug temperature. Find his profile on 'Search' and drop him a PM. I did and it helped a lot.

 

[Anonymous]

Spark Plug heat range has to due with the amount of heat that the plug transfers to the head. A hotter plug has a longer or more resistant path to tranfer the heat to the head, so the plug runs hotter. I do not know the numbering systems of the various plug manufacturers. But for instance, an AC 43 or 44 was run in old Vette engines. If fouling of the plugs was encountered, they recommended a hotter AC 45 plug.