buick 1956 nailhead engine

I was working with my car, when a notice that one of the cylinders was not working. Changed spark plug(Autolite 85, 032 gape), spark wire and l checked distributor(check and clean points, rotor, cap was ok, clean). Firing order was correct. Test again and still not working, Wire have spark (checked with a spark tester) Remove spark plug again, connected to the wire and the spark plug did worked ok, I can see the spark. Before put the spark plug back ,sprayed some Mistery Oil in the cylinder. Still no results. Engine runs ok, but when I remove the wire , is no change. Removce all the spark plug, and used Mistery Oil in all the cylinder. The car smoke a lot when I started but still that cylinder was not working. Removed all spark plug again and did a compression test. Everyone of the cylinders showed a 150 psi. Maybe a valve is not working in that cylinder? Any idea? What else can I do? remove valve cover? Thanks for your help in advance. Daniel

 

check for a vacuum leak near that cylinder.

 

Yeah,pull the valve cover and be sure valves are going up and down - especially the intake. If not, could be a rounded cam lobe. Also,check for mouse nests in that cylinder intake port.....

 

If you have 150 lbs compression in all cylinders, it is NOT a valve problem.

 

Test the plug wire with an ohm meter or change it out with another cylinder and see if the dead one comes to life.

jack vines

 

Update removed valve cover and valves were moving. Only thing left to do is a vacuum leak test(got kit for Harbor Freight). Anything else I can try? Thanks, Daniel.

 

Likely a vaccuum leak. I once 40 years ago had a 1963 352 ford that had a dead cylinder. I pulled the heads and done a valve job. then I changed the intake from a four bbl to a two bbl. I messed with it off and on for a few months. I finally figured it out. I started shifting the plug wires over one position on the cap . The next cyl went dead. I and found the lobe,s on the distributer where worn and the points where barely opening on that cyl. When I changed the distributer out I some how didnt get the hex shaft back in the oil pump. started it up and no oil pressure and clattering lifters. pulled the pan and fixed the shaft. cleaned up the metal shavings in the pan and put it back together. I drove it two more years. I junked the car. I was young and stupid. It was a four door HTP. Had bucket seats and a console automatic all the galaxie XL trim and was pretty solid. I just didnt want a four door. I still have the 352. You will get it figured out. There isnt a piece of cast iron in the world that can fool you unless you just let it. OldWolf

 

well yesterday did vacuum test and its.....ok!!! I dont understand ....test showed low leak (20 t0 25%). No sound of leaking air.Any other idea before a remove the head cylinders and take both to rebuild? Thanks, Daniel

 

At 150# you dont have a valve problem - pulling the heads and getting a valve job is not necessary and will not cure this fault - it is something else. Keep looking its either electrical or as listed before a vacuum leak. Has the intake manifold been off and the gaskets not resealing when it was put back on?.

 

Did change spark plug and wire( checked with a spark plug tester and have spark)did leak test and results were low( only 20%)did compression test and number (all cylinders ) was 150 . Didn't remove manifold or head cylinder. What else is left to do? Maybe distributor....( I have an extra one, will try it) or the problem is internal?, but the engine is almost new, very low miles(about 60 or 70,000). Thanks everyone for your help and advice? Daniel

 

Update on Buick 1956. Found a vacuum leak coming fron connection at the top of the motor(close to the cylinder not working) that connect a vacuum line to the dynoflow transmission.