No carbon in exhaust port of 396.

[SS396]

Bought a rebuilt 396 just recently but cant get it to run properly. There is no carbon in no. 8 cyl exhaust port whatsoever, clean as a whistle.Took rocker cover off to see if valves were opening and closing on that cylinder which they were so it has me stumped. I thought if the cyl wasnt firing you would still expect to see some residue or petrol in the port. Any ideas.

[tmodel66]

If it's not firing you won't see any on a new motor. Sounds like you have a dead plug. Did it flood before it  started?  Pull the plug and make sure it's firing and check the compression. Is it a solid or hydraulic lift.? If its hydraulic you might have a lifter bad or not primed.  PM me if you can't get it going


Daniel

[SS396]

Thanks  tmodel66. Theres carbon in the header tubes except no. 8, thats how I noticed this problem. Cam is hydraulic. Swapped plugs around and they are all new but its still the same. It has new leads and rebuilt dizzy so I don't think it's electrical. Next thing will be to check lifter and compression.

[bertfam]

A blown head gasket (or a cracked head) will do this. Water gets into the cylinder and "cleans" the carbon out. (Don't ask me how I know!) Are you loosing water from the radiator? Do a leakdown test and see what you come up with.

Ed

[SS396]

Water level in radiator is pretty constant and doesn't overheat. Motor is supposed to have been rebuilt so I would not have thought this would be a problem in case I got a dud.

[tmodel66]

Have you made sure the plug wire is fireing.  Put a plug in the  end of the wire and make sure it's fireing. If it is check the compression. You could have a warped push rod. Has the rocker stud pulled up out of the head any ? There is so many things you really have to go thru a step by step process.