Engine Help on dead cylinder

luisjluis1 said:

Anyone have a good distrutor coil combo I should buy?

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OEM system.

If you are so removed from an stock wiring system, maybe an older Duraspark unit with vacuum advance and use an MSD, Crane, Holley ignition box (much like the pre-EFI cars used.
Regarding aftermarket non-TFI units, take a chance if you like, many have had issues with MSD distributors and everything works when they go back to stock.

Man,I have an original dizzy out of an 85 GT that would work great.

10-1 compression doesn't mean much to my old mind, but 130-140-150 LB does. Getting spark just means that it has an ignition source, you also need fuel and air. If the intake runners are blocked or the valves are not opening, especially the intake valve, there would be no vacuum created which could account for dry ports. What is strange it is on both sides of the engine. My next step would be pull a valve cover and see if the valves are opening and closing. Another quick thing you can do is pull a spark plug in a cylinder that is not firing, remove the coil wire place your finger over the spark plug hole and have someone turn the key. You should feel the compression build up then a pop which you will feel on your finger, just like when you are setting it up to find TDC. No pop no air entering the cylinder = valves-lifters-rocker arms-cam etc. If you did a rebuild this should not be.. wish I was there to work on it....

Only one other thing I can think of that happened to me 60 years ago. Replaced a starter on a boat that had a 312 ford engine, for some reason the starter was rotating in the wrong direction and the motor would not start, only found out what was wrong by checking firing order at the distributor looking at a Motors Manual, it was turning in the wrong direction. Might check that, battery polarity wrong?? This is a tough one!

Not that this is the issue, but I had an 83 with a V6 that would start and run like a bag of . When you put it in gear it would stall. Back into park and would restart. Changed the engine (with another V6 at the time) and the shop checked into the old motor. Cam had snapped in middle. The back half of the cam was not turning at all. So it was running on 2 cylinders - no wonder is stalled in drive.

I would agree that valves not opening would definitely explain alot, but to have 4 cylinders spread over the entire length of the engine seems extremely unlikely (I could see 1 or 2, but 4 is a stretch.

92mustang74 said:

Another quick thing you can do is pull a spark plug in a cylinder that is not firing, remove the coil wire place your finger over the spark plug hole and have someone turn the key. You should feel the compression build up then a pop which you will feel on your finger, just like when you are setting it up to find TDC.

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This would be a good, free test to do on the 4 dead cylinders.

Luis , I am a retired automotive mechanic, 35 years at this stuff, dont know it all but a little. you need three tools and less parts. a previous poster suggested a Vacuum Guage, get one and learn how to read it. Second acquire a good thread in Compression Tester and diagnose readings. Fuel pressure Gauge , a carb takes less pressure than EFI so make sure on correct pressure, No need on buying/exchanging parts while frustrating the fun out of this.