37 Ford misfire

[dean333]

#2 & #5 plugs wet, not firing. Across from each other in the dizzy, hmmmm. Haven’t pulled the caps off yet.

[ford38v8]

Coincidence or condenser. You choose.

[Ken/Alabama]

Need to put the distributor on a distributor machine. Then that will rule out the distributor. Then it’s either caps or rotor. Or bad wires.

[fordscript]

I would check the spark plugs first, to make sure they arent bad

[dean333]

Spark plugs are new.

[47topless]

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Originally Posted by fordscript

I would check the spark plugs first, to make sure they arent bad

Good advice. New can be bad. Start at the end.

[dean333]

47topless: Start at the end?? Of?

[Ggmac]

It means start from the plugs back . New plugs don’t necessarily mean good . Swap plugs with another cyl thats firing . Then check compression , look for a vacuum leak on the two cylinders . Check plug wires with an ohm meter or if you have insulated plug pliers check for a good spark at plug end of wire . Hold wire about 1/8”- 1/4” away from grounded block . Be careful, make sure theres no open flammable liquids around !

[47topless]

Yes, what he said.
Another check would be to remove a suspected bad plug, plug it back into your plug wire, Crank the engine, holding the plug with insulated pliers, and observe the end of the plug. (Do this in the darkness of the engine bay). The spark coming from the plug should have some nice blue in it. If only a pale yellow, the spark may not be strong enough to fire the cylinder.
The tests suggested by Ggmac would be very helpful for you.
Good luck

[Bill OH]

Check your spark plug wires with an ohm meter - remove the wire harness and conduit to enable you to get at the cap terminals and use your ohmmeter to check the condition of the wires. Ford used copper core wires, but have the wires been replaced with carbon core wires (TVRS)? You may have a wire out of its socket in the distributor cap or the connector for the sparkplug is not making connection. How about the remaining cylinders - blue spark? If good, then i would check out the distributor caps and the wires.

[Bill OH]

Ggmac has given you good advice. If the tests I described above do not yield the problem, then I would suspect a vacuum leak - Cyls 2 & 5 are on the same runners in the intake manifold?

[Flathead Fever]

I have a Sun scope at home like I used at work for 30-years. Noi thing beats it for diagnosing ignition problems fast. I bought it for $200.00 because it was taking up too much room in the guy's garage. A couple things you can try is to hook a timing light to that #2 and #5 wires and see if they have a spark strong enough to trigger the timing light to flash. Doesn't mean they are firing at the correct time. The wires could be crossed or a cracked cap cross firing. Check the firing order to make sure the wires are correct. While it's running pull the plug wires one at a time with the best insulated pliers you have and compare the rpm drop between those cylinders and the good ones. Without it not running pull the wires off the plugs and just set them back on so you can easily remove them when it's running, do not remove wires on a running engine with electronic ignitions, that is a bad no-no.

[dean333]

Just checked for spark in the dark garage, nothing from 2 or 5. I’ll pull the caps tomorrow, hopefully the wires are not in the inner caps securely. I should be so lucky.

[cadillac512]

Tim, have you checked dwell by any chance? When the rubbing block wears on the points they sometimes stop triggering the coil on the distributor lobes that are a thou or two more worn. Just a thought....


Terry

[dean333]

No Terry, just checked plugs and two wires for spark on the plugs that weren’t firing.

[Terry,OH]

Since the solid wire core, not resistance type plug wires do not have spark and they have good continuity with near zero ohms the next check might be the inner distributor caps. Make sure the plug wires are fully pressed into the cap. If the caps are old the inside terminals may be too short to properly reach the rotor contacts. I have found some caps do not have electrical continuity from the wire end to the rotor end. This usually shows up on new caps. Check the coil contact with the rotor to make sure it has good spring action and the rotor does not have any hairline cracks in the brass.