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I have a 250 with Landon's headers Holley 390 on an offy manifold hei dizzy, plugs gapped at 60 per langdons instructions timed to 12 btdc and it doesn't seem to want to run right
Symptoms 5 and 6 black sooty plugs 4 brown and crusty 3,2,1 brown but cleaner, it left black soot on floor under exhaust, Jetted down 3 sizes and no more soot under exhaust and it seemed to run a little better
It has a miss pulled plug wires one at a time while running 1,2,3,4 make it run rough 5,6 no real change
Tried new plugs gapped to 45 to see if that would help it didn't switched plug wires to see if one was bad it didn't change anything also switched plugs around no change there either
tried new cap and rotor nothing
did a compression test all 6 at 110. Valves loosened tell clatter slowly tightened to zero lash and 1/4 turn more no change
I have driven around block a few times it does not run like it should it runs rough under load
I'm at a loss as to what to do help
 

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I
did a compression test all 6 at 110. Valves loosened tell clatter slowly tightened to zero lash and 1/4 turn more no change
I have a similiar setup on my 250, with a 500 cfm edelbrock, and Langdon equipment.

# 5 and 6 should have reacted just like the others. That should be a concern.

Your compression appears to be low. I would think an engine in good condition would have at least 135.

Your engine did not call for 12 degrees initial, but its Langdon's recommendation and it works.

If you made improvements by adjusting the carb, you may want to do some more in that area.
 

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I'm experienceing a rough running condition under load with my I6 right now. My problem is rust in the fuel system that i'm working on correcting.
How old is your gas tank? Did you check or change your fuel filter? Fuel pressure? How long has it been since the carb has been cleaned out and rebuilt? As far as the plugs, sounds like head needs the valves done or needs new valve seals. How fresh is the engine? What is its condition as far as the valves and cylinders, rings, etc.??
 

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Discussion Starter #5
I'm experienceing a rough running condition under load with my I6 right now. My problem is rust in the fuel system that i'm working on correcting.
How old is your gas tank? Did you check or change your fuel filter? Fuel pressure? How long has it been since the carb has been cleaned out and rebuilt? As far as the plugs, sounds like head needs the valves done or needs new valve seals. How fresh is the engine? What is its condition as far as the valves and cylinders, rings, etc.??
New tank new lines new filter new remanufactured carb new engine
I used r44xls plugs which are 1 step colder than my 65 manual says so I have a new set 1 step hotter which should be a better starting point any suggestions on what plugs I should use and what gap?
I have a 1962 valve cover which had the puke tube (i dont have the tube but i have the cap) and ran my pcv valve inline from that to the manifold i am thinking this isnt right so im going to move the hose to the back of the carb and see what happens
Until I can figure out the right pcv valve can I go without to get it running right
Or will there be problems?
I borrowed the compression tester I'm hoping it was working right all readings were so close to the same spot I'm hoping it's ok
I did the break in following the instructions that came with the engine using the break in oil that came with it
I have an oberg oil filter checked it after break in and there were no metal particles I could see and double checked it with a magnet still stumped but am gonna run it tomorrow and see what happens
 

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Check your spark wires for proper resistance. I've seen new wires that go bad quickly and do not carry proper voltage to the plugs.
Also, you might go out at night and start the car and watch to see if you have arching from one wire to another or to another ground source.
 
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