Engine question

[skyshark186]

K, i know this isnt a chevy site but i know someone else has an early 350 in their truck. For some reason, the left bank of my motor smokes like hell SOMETIMES. Other times its fine. Sometimes it backfires, sometimes it dont. The right is just fine. No smoke, no boom. The engine runs good, always has full power even when smoking.

Bad cylinder maybe? Spark problem?

Im kinda short on ideas, any help would be a lifesaver.

 

[largenfirm]

Have you looked at the plugs? Their condition can tell you a lot.

How's your oil consumption? Have you checked wet and dry compression?

Kirk

 

[skyshark186]

Just went out and pulled the plugs. I put a new set in and really havent driven it a hell of a lot. Couple hundred miles maybe, and they are black. Nasty lookin, and the left bank plugs have tons of carbon build up. Havent done a compression test, and it really doesnt use oil at all.

Dont know whether to just replace the plugs again or what. Most of the "chevy" guys i know say to just use regular plugs in 350s, no bosch or premiums. That true?

 

[VTFJ40]

I had the same experience. I think it was from starting cold and not driving it alot. Once I started puttin some miles on it, plugs stopped blackening up. But as soon as I park it for the winter and just start it occasionally, It happened again.

 

[skyshark186]

Ohh i drive it daily. Its my only vehicle. It just dont go to far. I just think its wierd that it only does things occasionally.

Moody, just like women J/k

Any advice. Id like to at least make it stop smoking and backfiring. Other than that it can eat plugs and ill replace em twice a year.

 

[IDave]

Assuming your plugs' black is carbon black, not oily black, think about too rich fuel mixture (jets and/or idle needle), sticking choke, plugged air filter, worn points, overly retarded timing, or just generally low compression. Your plug temperature may be wrong as well. You may be carboning up and burning it off when you drive, so that it seems intermittant. OR maybe your choke is sticking intermittantly. But anyway, carbon fouling suggests incomplete combustion for some reason.

 

[skyshark186]

Thanks a lot for your help. I have a HEI system on it, so it probably shouldnt be that. We tuned it way down so it would pass emitions and maybe we got a little carried away. Ill replace the plugs, gap them a little better, and fiddle around with the idle/fuel mixture. Thanks again