Advice needed!!! Smoke on one side of exhaust

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65valiantwin

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Windsor, Ont.
Hey guys, built a new engine about 2 years ago as follows:

360 stroked to 408
Comp ks671-20 cam. Duration 284/291, Lift .484/.484 , LSA 108
LD340 intake with divider ground most of way down
new edelbrock performer 600 carb (I know it's too small, new one on way)

Anyways, here's my issue. It's run maybe a total of 25 minutes since rebuild, but recently when we've been setting timing, etc. we're getting rich exhaust (unburnt fuel, NOT oil) out of only one side (Passenger) after it warms up, completely normal exhaust out of the other side. Not running H pipe, exhaust straight back from headers. The engine is running/sounding great otherwise. I cannot figure out for the life of me what the problem could be, i'll be pulling plugs/compression testing tonight but was wondering if anyone had any ideas?

Thanks in advance
 
Hey guys, built a new engine about 2 years ago as follows:

360 stroked to 408
Comp ks671-20 cam. Duration 284/291, Lift .484/.484 , LSA 108
LD340 intake with divider ground most of way down
new edelbrock performer 600 carb (I know it's too small, new one on way)

Anyways, here's my issue. It's run maybe a total of 25 minutes since rebuild, but recently when we've been setting timing, etc. we're getting rich exhaust (unburnt fuel, NOT oil) out of only one side (Passenger) after it warms up, completely normal exhaust out of the other side. I cannot figure out for the life of me what the problem could be, i'll be pulling plugs/compression testing tonight but was wondering if anyone had any ideas?

Thanks in advance
dead plug wire on one side? I seen this once on a new set of wires.....
 
Got a timing light?
You can check the wires on the suspect bank by putting the light on there (your not checking time, just spark)

Next, pull the valve cover and see what the rockers are doing?
 
How do you know what it is or what it's not? Have you had it analyzed? Never simply assume. It can fool you. I go along with what rumblefish said. I would be checking the valve seals on that side. It's easy and costs nothing to check.
 
Can't discount the valve seal warnings....
Have you checked your wires? You may have pulled a connector loose from the wire when you removed them for the rebuild. Ohm test them. Or just do a 'balance test' to isolate the offending cyl/wire/other. It will narrow it down for you, at least.
 
What happened with the old engine.? ?
Did it have a bad cylinder that side or did anything happen to fill one exhaust pipe with oil or coolant ? ?
 
What happened with the old engine.? ?
Did it have a bad cylinder that side or did anything happen to fill one exhaust pipe with oil or coolant ? ?


Hey Inertia, thanks for your reply, it was a "new" build, just got the core block from someone and built from there, wasn't my engine previously. There isn't anything in the pipes.
 
Certainly sounds like a weak firing cylinder; a dribble out of one side of the carb ought to show up on both banks with that intake type. Just some more things to check:
- Check each spark plug wire for resistance end-to-end and see if one is much higher in resistance than the rest.
- Look at the valve lift on all cylinders as suggested. (Not always easy with hydraulics if they leak down any.)

What plugs do you have? Resistor or non-resistor?
 
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